Expert Discussion on Frame Stiffness

Expert Discussion on Frame Stiffness

“I no longer believe that the ultimate rigidity defines the ultimate bike!” That revolutionary statement came from Damon Rinard, Road Engineering Manager at Cannondale, in a recent podcast on frame stiffness and “planing”.
For many decades, stiffer frames were thought to perform better. Frame flex was equated with wasted energy. And yet there were some who had doubts about this. I recall Peter Weigle telling me many years ago, when I complained about a test bike that just didn’t seem to perform: “Perhaps it’s too stiff for you?”

Back then, the idea that frame stiffness could negatively affect performance seemed far-fetched, but the more we researched it, the more we found that some frames performed better than others. And for us, more flexible frames – as long as the flex was in the right places – performed better. We coined a term for this: “Planing” took the image of a boat that rises out of the water and goes faster with less energy than when it was fully submerged.

Even though the concept wasn’t entirely new, “planing” went against decades of accepted wisdom in the bike industry. Our double-blind studies (above) were carefully designed, but at first, they were met with incredulity or even derision. After all, bike makers spent significant resources figuring out how to make their frames stiffer, and magazines determined the “stiffness-to-weight ratio” as the ultimate measure of a frame’s performance. How could all this be wrong?
Recently, James Huang, technical editor of the popular web site, asked me whether I could participate in a podcast on frame stiffness with Damon Rinard from Cannondale. Cannondale! The company’s bikes are famous for their stiff frames, and Damon is one of the foremost researchers on frame stiffness. I was bracing for a heated discussion!
But Damon is a smart guy, and rather than accept the conventional wisdom that frame flex is lost energy, he has tried to quantify these losses. And he came up empty-handed. It appears that no energy is lost when the frame flexes. There is no doubt that bike frames flex, but apparently, that energy is returned to the drivetrain, so it powers the bike forward.
That formed a fascinating basis for our discussion. We both agree that frame flex doesn’t rob energy. But could it be beneficial? Click here to listen to the podcast and hear the entire discussion.
Further reading:

Share this post

Comments (53)

  • Osvaldo Colavin

    For what it’s worth, in electronics, power transmission is analyzed in the frequency domain (spectral analysis) and I believe this formal approach would bring much insight on the topic at hand. From this perspective, the frame is a filter that attenuates power differently at different frequencies; the rider’s power spectral density will show power concentrated at some frequencies (in particular at twice the cadence frequency but at other frequencies too that I strongly suspect are rider specific). A bike will “plane” for a given rider if the troughs in the frame’s frequency response do not match with peaks in the rider’s power spectral density. This does not contradict the remarks of the original post, on the contrary. One prediction that can be made from this model is that a given frame will work better for some riders than for others.
    Also, some power is necessarily lost when the frame flexes, or this would violate the laws of physics. It’s possible that the loss is so small that it is difficult to measure.

    June 6, 2017 at 10:40 am
    • Jan Heine, Editor, Bicycle Quarterly

      Interesting analogy… The energy lost due to hysteresis as the frame flexes is too little to measure. In theory, carbon frames have higher energy losses than metals, but in practice, it simply doesn’t matter.

      June 6, 2017 at 11:24 am
  • PK

    You and I will do pushups. You get concrete and I get the diving board.

    June 6, 2017 at 10:41 am
    • Francisco

      While this kind of analogy seems to offer a satisfyingly intuitive grasp of the problem I think it is actually misleading. The pliancy of springboards and ballet floors protects against impact injury and, by elastically storing some energy, aids the tendons and muscles in propelling the body upwards.
      The pedalling movement has little in common with this. There is no meaningful impact stress and the purpose of the movement is not to propel the body upwards; quite the opposite, bobbing up and down is undesirable.
      A gymnast on a springbed can be modelled mathematically quite well as an oscillating system comprised of a mass and (variable rate) spring. I do not think this kind of model has any relevance to the pedalling movement.
      In the podcast Jan stresses that ‘planing’ somehow involves a match between frame flexibility and body mechanics/physiology. Gary Houchin-Miller demonstrated mathematically that elastic energy stored in the frame ends up propelling the bicycle, for the particular case of a sine-wave pedalling input. Proving that this is the case for higher-order harmonics as well (as suggested above by Covalin) would allow us to demonstrate that the same is true also for the ‘peaky’ pedalling forces, as any wave profile can be decomposed into harmonics (with a technique called Fourier transform). I venture to forecast that seated pedalling will be shown to be just as efficiently transmitted through the frame to the wheels as is the case for a pure sinewave, but that the squarish wave profile of pedalling while standing has a small amount of very high-order harmonic content that is NOT translated efficiently by the frame.
      The body mechanics-side of things is certainly much more complicated. Intuitively I imagine a small advantage is gained in abreviating the amount of time spent at the beginning of the downward stroke when the knees are maximally bent, while dilating slightly the time spent at the end of the dowward stroke when the leg is fully extended and can thus maintain a downward force with less effort. It can also be hypothesised that the reciprocating mass of the rotating legs, the side-swaying mass of the upper body and springiness of the frame may match in a constructive way for certain values of pedalling cadence and power. I do not know how to test (model or measure) this hypothesis.

      June 8, 2017 at 3:02 am
  • Ken B

    Straddling the bike, if you firmly apply the brakes to both wheels to hold the bike in place and press down on the front pedal, you can see the frame flexing and the bottom bracket deflecting. Is this the type of flex that contributes to planing? Of the frames in my stable, my SOMA Grand Randonneur is the easiest to flex in this manner, and I found the frame climbed well for me, although your experience was quite different. Is this a legitimate way of gauging how much flex there is in the frame?

    June 6, 2017 at 12:18 pm
  • Charles

    I wonder if it makes a difference on the type of riding done – sprinting vs longer rides.
    I have some “nice” steel bikes. A KHS track bike and an ’94 Specialized Allez. If I’m doing a long ride I don’t’ feel I lose anything with the steel bike. But I feel a large difference when sprinting: accelerating with a group or closing a gap at the Velodrome or a hard road ride. With the steel bikes I’m drained on hard acceleration and may not be able to hang on or do another hard effort. With similar Aluminum bikes, I feel the bikes jump when I put the power down and don’t suck everything I have on acceleration. While the steel bikes might be as efficient and more relaxing on a long ride, with short sprints the don’t seem to have the responsiveness and efficient transfer of energy of a stiffer frame.

    June 6, 2017 at 1:39 pm
    • Jan Heine, Editor, Bicycle Quarterly

      All the data I’ve seen indicates that frame stiffness and power output should be related. When riding very stiff bikes, I can make them work fine for a limited amount of time – until I fatigue… In the 1960s, many pro racers had ultralight (and hence flexible) frames for time trials (constant effort, moderate power), but rode standard frames for road races, which are won in a few bursts of acceleration.

      June 6, 2017 at 6:19 pm
  • Andy Stow

    Exactly. A frame that flexed enough to exceed its elastic limit wouldn’t last long.

    June 6, 2017 at 1:39 pm
  • james

    I don’t believe that flex at the bottom bracket has anything to do with power transmission efficiency. As Damon found with his two watt meter experiment, there was no practical difference between frames in this regard.
    What isn’t measured by this method though, is suspension losses. A stiffer frame will transmit more of the higher frequencies of road buzz than a softer frame to the rider for their body to absorb. A softer frame, like wider softer tyres, helps to smooth the road surface vibrations – even if it does feel like a noodle when you stand up to sprint.

    June 6, 2017 at 1:55 pm
    • Jan Heine, Editor, Bicycle Quarterly

      Interestingly, frame stiffness and “noodly feel when sprinting” are not always correlated. Many racers’ favorite frames, the ones that sprint the best, are actually quite flexible. Just like Damon described for Shaun Wallace, who prefered the more flexible bike for the pursuit – an event with huge power outpt.

      June 6, 2017 at 6:16 pm
      • james

        My old 853 frame & fork with 1″ tubes is smooth to ride, but a noodle to sprint on. My current Columbus Spirit frame with oversize tubes & CFRP/Aluminium fork is far stiffer, so I use a 27mm rear tyre at lower pressure to smooth the road – but I sprint much better on it. It feels like I’m going to twist the old 853 frame into a taco!

        June 6, 2017 at 9:42 pm
      • james

        Yesterday I did a little test. With my body weight I pushed down on the top tube very near the head tube and watched the front axle. On the 853 frame & fork the axle moved forward several millimetres. On the Columbus Spirit frame with CFRP/aluminium fork (1 1/8″ steerer too), the axle only moved forward 1-2mm at most.
        Food for thought on my suspension theory above.

        June 7, 2017 at 3:24 pm
  • Eric Genzlinger

    This is very informative, that an engineer is unable to obtain meaningful measurements of frame stiffness that can predict performance. So the conclusion so far is that frame stiffness is not a reliable predictor of bike performance (which is a substantial admission) which was the conventional wisdom for decades. But BQ’s tests are concluding that frame stiffness (or lack there of) is a reliable predictor of rider performance. The only thing that I have found missing with all of the tests of frame flex, or planning in BQ is that the sample size of rider types has been really narrow. You have provided a lot of performance data that shows the performance gains that you and Mark achieve with a thin wall tube bike but I need to re-read the BQ tests again. I know many different bikes have been tested but how many different riders have been tested? It could be that the overwhelming majority of BQ subscribers are male, CAT2, 6ft tall, 150 lbs and live in the mountains so they all may find that very flexible frames are the ticket to optimum performance (along with supple tires etc). And just so I am not misunderstood, I think that frame stiffness is not a predictor of bike performance The tough part is that rider performance is subjective. And most of us don’t have access to test ride multiple bikes over hundreds of miles to determine what our optimum frame stiffness is so that we feel confident when we engage a constructor with thousands of dollars to build us a bike that “planes”, but that is why we find BQ so valuable. However, my hesitation is that I am not CAT2, 6ft tall, 150 lbs or live in the mountains. Could you get folks of different weights and abilities to test ride a bike that planes vs one that doesn’t? I guess the height would have to be the same so the bike fits. . Once again, I have subscribed to BQ for about 8 or 9 years now because the information that you provide can be found no where else. I will continue to be a subscriber in the future.

    June 6, 2017 at 2:55 pm
    • Jan Heine, Editor, Bicycle Quarterly

      You are absolutely right – our test only showed that for two riders, frame stiffness does affect the rider’s power output and performance. From this, we cannot easily extrapolate how to build optimized bikes for other riders. To do a broad-based study would be very neat, but it would require hundreds of riders to be meaningful: What if 10% of riders weighing 220 lb and being 6’2″ tall can feel a difference. And it would require dozens of bikes… Unfortunately, that type of study exceeds the means of not just Bicycle Quarterly, but probably anybody in the bike industry.
      I think this is where the experience of good framebuilders comes in. By working with many customers and getting feedback about the bikes they build, they can fine-tune the bikes so they perform optimally for the rider. Ideally, the builder sees you ride your bike, so he or she can observe your pedal strokes first-hand…

      June 6, 2017 at 6:13 pm
      • Eric Genzlinger

        Agreed, an exhaustive test would bust the marketing budget of even a large bike manufacturer. But a sample size of 2 guys who are 200 lbs (or 33% heavier than you guys) would be meaningful.
        By the way, I would like to toss a few compliments your way. Your teams research and observations over the years has greatly improved our understanding of the factors that affect the enjoyable performance aspects of biking. The entirety of this information cannot be found elsewhere except in bits and pieces Before during and after the war, the French rode bicycles because cars were a luxury. Today in the states, we drive cars because we have to and biking is a luxury.The French had mostly perfected all of the critical aspects of enjoyable performance biking. It appears the Japanese were the first to rediscover this knowledge, but you have resurrected it in the USA and maybe now also back in France. The tire tests are nothing short of a revolution in the bike industry. I would like to personally thank you and inform you that I am a highly satisfied customer and enthusiast!! Keep it coming!

        June 6, 2017 at 6:46 pm
        • Jan Heine, Editor, Bicycle Quarterly

          Thank you for the kind words, but really, we are just building on the work of generations of builders and riders all over the world. In the past, many American builders talked to me about “lively” frames or bikes that just want to go…

          June 6, 2017 at 7:00 pm
  • John Hawrylak

    Jan, you wrote “We coined a term for this: “Planing”…” I recall other podcasts and blogs identifying Matt Grimes as “coining” the phrase. Only looking to give credit to where it is due.
    John Hawrylak
    Woodstown NJ

    June 6, 2017 at 3:09 pm
    • Jan Heine, Editor, Bicycle Quarterly

      I talked to Matthew Grimm of Kogswell about the concept of the boat rising out of the water. I didn’t know the technical term for it. Matthew then said: “Ah, you mean planing.” And then we started using the term… So the idea was ours, but the vocabulary lesson came from Matthew.

      June 6, 2017 at 5:43 pm
  • Jacob Musha

    This was great to listen to. It’s amazing how much evidence and time it takes to dispel a commonly held belief, even when (or maybe *especially* when) the belief has no evidence to support it!
    How much do you think frame stiffness matters in a low effort situation? For example, cruising a flat section with no wind at 30km/h. I like to go all-out sometimes. But in reality, it’s probably a very small fraction of my riding time.
    This makes me want to do some of my own experimenting with my lugged aluminum SR Litage compared to a much stiffer steel touring bike. I’m curious if I’ll be able to feel the difference in leg versus cardiovascular exhaustion.

    June 6, 2017 at 3:55 pm
    • Jan Heine, Editor, Bicycle Quarterly

      I’ve thought about that – randonneuring is very much a moderate effort for long times, rather than all-out sprints and climbs. There are some bikes that just want to keep going, even at moderate speeds, and others that I have to coax along…

      June 6, 2017 at 6:57 pm
  • Brucey

    For a long time (back in the days of steel frames or nothing) I hankered after a really stiff frame, if for no other reason that maybe then I wouldn’t be chafing both sides of the front mech when going ‘full gas’. At this time I remember also being mystified by Sean Kelly’s ability to propel his flexy Vitus down the road in a roughly straight line; he looked more likely to tie the thing in a knot than anything else….
    Eventually I got a very stiff frame, and whilst ‘silence was golden’ going full gas, I found that I didn’t really like it to ride on and I wasn’t sure that it was any quicker 90% of the time. It certainly wasn’t comfortable or anything….
    So my view is that if there are mechanical losses in a flexy frame, they are probably rather small. But more importantly the rider is not a simple machine; it is relatively easy to ‘pedal badly’, i.e. push on the pedals in a way that doesn’t help the bike go forwards; ‘hard work’ for a human being doesn’t always translate to ‘work done’ as measured by physics. Take the example of holding a heavy weight; this is very tiring but according to physics ‘no work is done’. On the bike, pushing hard on the pedals (say) when the cranks are vertical is tiring for the rider but not productive.
    I now believe that anything that helps to avoid this can result in a faster more efficient bike. Possibly there is a real effect whereby energy is more likely to be stored in a useful way even if the rider is ‘pedalling badly’. However I also think that because a springy frame ‘talks to you’ with every pedal stroke, it may encourage the rider to simply pedal better, more consistently, than on a stiffer frame. The ability to pedal in sympathy with the frame and to take advantage of any feedback may be something that has to be learned, too. If so, this may help to explain some of the observations that have been made, including that for some riders, they neither notice nor benefit from riding a less stiff frame; for these riders it may not matter if the frame is providing good feedback, if they cannot take advantage of it.

    June 6, 2017 at 4:25 pm
    • Jan Heine, Editor, Bicycle Quarterly

      However I also think that because a springy frame ‘talks to you’ with every pedal stroke, it may encourage the rider to simply pedal better, more consistently, than on a stiffer frame.

      That is a very interesting thought!

      June 6, 2017 at 6:54 pm
  • Robert Paul Glassen

    ” ‘Planing’ took the image of a boat that rises out of the water and goes faster with less energy than when it was fully submerged.” The only boat that is fully submerged is a submarine, (or a sunken boat).
    A planing boat is one whose weight is partially supported by hydrodynamic forces. A non-planing boat is a displacement hull, one supported by its buoyancy, equivalent to the weight of water it displaces. Still, as applied to bicycles, the image is useful as long as you are not too familiar with naval architecture.
    It is a very hard sell convincing cyclists to ignore the vibrations of hard, narrow tires and stiff frames as an indicator of speed. Back in the 1960s I once had a ride in a Ferrari GTO, Yes, the real, ex-race thing. Exciting? YES! But it was perhaps the most unpleasant automobile to ride in I have ever experienced. Rattly vibrating sheet aluminium, screaming gear box at your thigh, hard metal surfaces everywhere, crashing sound and impact of suspension (I use the term loosely). It ‘felt’ fast even when we weren’t going particularly fast. Doubtless, it would have been more tolerable had I the distraction of being at the wheel.

    June 6, 2017 at 6:54 pm
  • Jason Marshall (@jmarshall312)

    Very good conversation on the podcast. Towards the close you were talking about the prospect of manufactures offering different frame characteristics for different riders in an effort to tune the frame to the particular rider. Golf equiptment manufactures have been doing something similar for a while now. They offer clubs with different flex characteristics for different swing speeds, flexibility etc. Obviously the challenge with bikes is to determine what particulars will work for a given rider but I think the parallel is there. One ‘size’ rarely fits all.

    June 6, 2017 at 9:01 pm
  • Waldo

    So much of a given bike’s feel depends on a rider’s fitness. A bike may plane for me when I am strong, but not feel as if it’s performing nearly as well after I’d had a long break from cycling.

    June 6, 2017 at 10:55 pm
  • Stuart Fogg

    Thanks for the interesting discussion! My other physical activity is rowing. Rowers have different preferences for blade shape and shaft stiffness which together are similar to bicycle frame stiffness. Unfortunately our displacement hulls can’t plane, but we use the term “swing” to describe a situation where the boat feels like it’s flying because everyone is rowing in perfect harmony.

    June 6, 2017 at 11:55 pm
  • Luis Bernhardt

    This was a fascinating podcast and quite an interesting subject. Two points stood out for me: 1) Grant Peterson’s comment about jumping on a concrete floor vs a sprung floor, and 2) Damon’s inability to measure any noticeable difference between power at the cranks and power at the rear hub, leading to the conclusion that there’s nothing to measure. “Planing” is based on the frame flexing and then returning this flex energy somehow along the chain and rear hub. When I read your first article about planing, I found this notion hard to absorb. I was referred to an engineering paper that tried to ascribe this transfer to the end of the power stroke. The frame springs back, but the legs still have to be applying power for this to work. At least that’s what I got out of the paper. However, I still find this hard to believe. The amount of flex is so small, and the return would have to be happening when the legs have stopped applying power (at or near top dead center).
    So how’s this for a theory of what’s going on: There is no such thing as a frame “planing.” Frame flex does not return any power. Instead, what the frame flex does is to optimize muscle preload and contraction, just like a wood floor vs concrete. If the floor is too springy, it absorbs power. If it’s concrete, it makes it too hard for the muscles to properly begin contracting. When it’s just right, it optimizes how the muscles contract. A frame that’s optimal will allow the muscles to contract properly on each pedal stroke.
    Rather than a boating analogy, I think a classic technique cross-country ski analogy would be better. Waxed skis need to be the right stiffness for the skier. They need to be stiff enough that the waxed part of the base is held off the snow until the skier puts all their body weight onto that ski, flattening the wax pocket so it contacts the snow and provides grip. When the skier pushes off, the ski returns to its original shape, but the propulsion is provided by the skier pushing down into the snow. The ski springing back has negligible impact, but the ski flexing during the preload optimizes the muscle contraction.
    I tend to agree with Damon, that the bike flexing is not that important, unless it can be quantified and customized for that rider. Maybe a bike fit can include a recording of how much force a rider can apply at the pedals, both sitting and standing, so it can be matched with optimal amount of deflection at the bottom bracket for best muscle contraction. Frames can then be sold in various degrees of stiffness. I think a good place to start would be to measure the force the pro’s can apply, and the deflection of their bikes’ bb’s, and start to find some correlations, patterns, and extrapolations.

    June 7, 2017 at 12:08 am
    • Jan Heine, Editor, Bicycle Quarterly

      what the frame flex does is to optimize muscle preload and contraction, just like a wood floor vs concrete.

      One reason we used the term “planing” rather than “impedence matching” or something more descriptive is that we know these frames work better for our testers, but we don’t know why. Your hypothesis is interesting and could be correct, too.

      June 7, 2017 at 7:34 am
    • Conrad

      I had the same thought about downhill skis too: a heavy and/or strong skier will probably prefer a stiff ski; a lighter or less technically proficient skier will prefer a softer ski. The energy stored in a flexed ski is returned to you at the end of a turn.

      June 8, 2017 at 8:26 am
  • Robert Freeman

    Back in the early 90s, Davis Phinney gave a talk at the Seattle Club, during which he described two bikes he had from the same manufacturer, not sure who at the moment, but maybe Serotta. But one he felt was noticeably faster, though they looked nearly identical. So they decided to do some testing on it and discovered that the faster one was made of lighter tubing, and was noticeably flexier. We at Davidson had been building steel bikes on the edge of lightness for some time, feeling the same way, so this confirmed our thoughts in a very real way. My own Davidson Impulse from 1986 which was the prototype, was built with Tange Prestige in .7-.4 wall thickness, and my later custom bike even lighter, .6-.3.

    June 7, 2017 at 3:50 am
  • Brucey

    the assertion in a comment above that the legs have to be maintaining muscular pressure on the pedals for the frame to ‘unwind’ and therefore recover stored energy at the bottom of the pedal stroke is mistaken. The reason for this is that the whole leg is decelerating in the vertical plane as the pedal approaches the bottom of the pedal stroke. This means that there is always an inertially generated load between the leg and pedal at this point in the pedal stroke, which can therefore react to the frame unwinding.
    If the leg were more or less rigid at the ankle joint, this inertial force would be applied to the pedal in return for zero effort on the part of the rider. However the rider has to at least exert a little force at the ankle joint in order for this force to be applied. This isn’t zero effort, but it isn’t every much effort either; if it were not applied then the heel might drop at the bottom of the pedal stroke which would be counterproductive anyway, so I think if there is any extra effort required, it is likely to be minimal.
    It is quite noticeable that load measurements through the pedal stroke always (i.e. with trained or untrained riders) show a marked increase in load through the second half of the pedal stroke, almost as if the rider is pushing on the pedal at the wrong time. Usually the peak load (looking at the RH crank) appears at between four o’clock and about five o’clock, and there is still an appreciable vertical load on the pedal when it is at the six o’clock position. The apparent mistiming and the residual load at the dead spot are both manifestations of the inertial component in the pedal loading.
    That this is the usual pedal loading is also very evident if you examine worn chainrings; they always betray the rider’s pedal stroke quite clearly, since they wear most at the top when the chain engages with the teeth and the teeth see the load. For example about 1/3rd of all riders are clearly quite strongly one-legged, in that their worn chainrings don’t display good 180 degree rotational symmetry. I have examined hundreds of worn chainrings and I have never, ever seen one that manifested wear in such a way that it shows that the rider is pedalling hardest at (say) the two-o’clock position, or some other place; the wear pattern is always in good accordance with the usual force distribution as described above.

    June 7, 2017 at 8:17 am
  • Marco O.

    Maybe (hypothesis) when a frame “planes” at a given rider speed, it has a natural frequency (in lateral torsion) close to the cadence of the rider at that speed. So it kinda resonates with the pedal strokes and this in some way maybe reduces the perceived effort due to some physiological reason. It should not be hard to measure the natural frequency of a frame with an apparatus like that drawn in the image above and a high speed camera (but in that case, I suppose the excitation force should be placed at the rear wheel hub/dropout and not at the bottom bracket). If just the flexible frame (between the two above) has a natural frequency very close to the cadence of the riders when they experienced “planing”, that would be a very strong clue to the possible explanation of the phenomenon.

    June 7, 2017 at 10:40 am
    • Jan Heine, Editor, Bicycle Quarterly

      There is no doubt the frame flexes. When we were in the wind tunnel years ago, my Alex Singer was mounted with the front and rear dropouts to a fixture. Even from outside the tunnel, looking in, the BQ team noticed how much the BB was flexing, even though I was pedaling with a relatively low power output. The wind tunnel team’s comment: “Last month we had Lance Armstrong here. His bottom bracket moved at least as much.”

      June 7, 2017 at 11:21 am
    • Francisco

      It should not be hard to measure the natural frequency of a frame with an apparatus like that drawn in the image above […]

      The natural frequency of a steel frame is probably in the audible range because the mass of the frame is so small compared to its stiffness. It will have no bearing on the phenomenon of planing.
      The natural frequency of the frame (spring) plus rider (mass) is perhaps more relevant but can it be measured? The bike plus rider as an oscillating system has multiple vibration modes, very high damping and, critically, several quite indeterminate linkages. A laboratorial nightmare.

      June 8, 2017 at 4:06 am
  • Tony

    For what it’s worth, I’ve tried to chase this phenomenon and have had interesting results. When I procured a 1984 Japanese-made Trek 400, my commute time was slashed by 10-15 minutes from the city bike I had. The first new bike I got myself was next, a modern production light-tourer w/ oversized tubes – I don’t know the thicknesses. Not happy with the tire clearances I sold it for a ’92 Bridgestone XO-2, with standard diameter tubing, obviously, but pretty stout. I found that even with Rat Trap Passes the bike is a bit leaden compared to the oversized bike w/ Barlow Passes.
    The Trek – again I don’t know the tube thickness – is set up as a fixed gear bike and it’s the only one that “planes” for me. It’s probably a combination of factors but at 6’2 and 185ish lbs this bike is what I’m roughly looking for in a future road build

    June 7, 2017 at 11:44 am
    • M. Davidson (@CabezadeShaka)

      I was thinking of a fixed gear bicycle’s use of inertia through the TDC and BDC of the pedal stroke as I read Brucey’s reply above. Of the many bikes I’ve owned over the years, those with ride characteristics that could be described most closely as ‘planing’ are steel fixed gear bikes. I’ve pondered this planing phenomenon for a while but never could get my head around it exactly since I’m a social scientist rather than a hard scientist. My own explanation is that planing is finding the rhythm and force required to drive a pendulum (the bicycle) as perceptibly efficient as possible. Thus, it’s more a metaphysical explanation to a human experience. Thanks for the data!

      June 9, 2017 at 1:31 am
      • Tony Hunt

        I’ve found the force of riding fixed feels significantly higher than with other drivetrains. But at the same time this bike “urges me” to pedal harder even late in rides. I take this to be part of what Jan means. At 60cm it’s a little small for me. I’m hoping to snag a larger 25″ Trek 630 with 531c. My thought is that the, presumably, better steel, as well as the less-triangulated main tubes, will give me what I’m looking for aside from a custom ride, which I can’t afford night now

        June 9, 2017 at 3:30 pm
  • marmotte27

    Your findings on planing confirmed what I ‘knew’ intuitively, while looking at bikes and reading tests in the early noughties, when steel bikes with slender tubes seemed definitely on the way out. In the bike press, it was all about stiffness, however the testers were always talking about having to put the power on to make the bike respond. I didn’t like the look of those bikes, and not being a racer or strong rider myself, got suspicious about the use of those stiff aluminium or carbon frames to the 95% of normal riders out there on the roads.
    I then got one of those latter day steel frames, where manufacturers wanted to make steel competitive on the stiffness front, and I can still remember how exhausted I felt after many rides. On the last climb of the day, I always had the impression of having to struggle with the bike to make it go forward.
    When I reverted to a bike with a slender steel frame (thanks to BQ), this feeling was entirely gone. The bike continues to perform, whatever my level of fatigue. Your claim was to promote real world riding, and the simple truth is, very few of the real riders are racers with enough power to bend a stiff frame to their will. Thank you for working ‘for the many, not the few’.

    June 8, 2017 at 2:59 am
  • BYcycles

    Great stuff. I really enjoyed that podcast– with you three “heads of state” it was sort of like the Yalta Conference on Bike Stiffness 😀 I really hope the idea of stiffer=better gets debunked if for no other reason that maybe the industry might stop inventing new BB “standards” that deliver all headaches and no real benefits to cyclists.

    June 8, 2017 at 6:44 am
    • marmotte27

      As Jan and his crew proved in one of their research projects (“Are Modern Bikes Faster?”), no technical innovation in bicycles since roughly the beginning of the 20th century has had any real benefits to cyclists, apart from the switch to butted thinwall steel tubes (the ones that make those flexible frames) in the 1930s.Still my favourite BQ article (was it 2009 or 2010?).

      June 8, 2017 at 10:40 am
      • Jan Heine, Editor, Bicycle Quarterly

        Well, we didn’t exactly “prove” it, because other factors could also explain the huge increase in race speeds during the early 1930s.
        We compared the average speeds in the Tour de France with medium-distance runners. We figured that the runners gave a baseline of improved human performance. If bicycle technology improved, then racers would not just outpace the advances of the runners, but also see jumps in performance as new technology was adopted. What we did show was that none of the much-touted advances actually increased the speeds of the racers, whether it’s derailleurs, indexed shifting or carbon frames. As Martin pointed out, the only time when bike racers’ performance improved more than the runners was during the early 1930s. Coincidentally or not, that was the time when racing bikes went from relatively heavy machines to modern lightweight frames…

        June 8, 2017 at 11:22 am
      • BYcycles

        Makes sense to me–“fast” is mostly about the engine. Anquetil, Merckx, Gimondi, et. al. Could bang out 30mph TTs using no special aero equipment. They were just “fast”. I could probably accept “innovations” that didn’t make me faster if they at least provided some other benefit–e.g. If they made the bike easier to service and maintain. Pressfit BBs, internal cable routing, disc brakes, electronic shifting, road tubeless, these all seem like needless complications to an otherwise wonderfully simple machine. Admittedly, I like STI brifters, clipless pedals, and threadless headsets. None of them make me faster but I like their convenience and/or aesthetic.

        June 8, 2017 at 1:42 pm
  • Mark Beer

    Totally agree with above (last two contributors). Bike industry is driven by the need to “innovate” to sell new stuff to the punters and they use race bike technology to promote their offerings. How many of us are racers?
    I love old bikes and have quite a collection. Among these are a late 70’s Masi Grand Criterium and a later Masi 3V Volumetrica, the latter built with oversize tubing and internal lugs (once described as the stiffest frame available). The first is a joy to ride, the second an exhausting challenge, but doubtless faster in a short sprint. And to confirm my entirely subjective and non scientific musings I have just built up a Condor “Paris” Galibier (if you don’t know it look up the frame design) and it’s like the Masi GC but more so. Jan Heine come over to UK and feel what a flexy top tube really feels like! Yet it tracks superbly on bumpy bends and downhills. Wouldn’t suit Cavendish and co however.
    Like other contributors I would like to thank JH and the BQ team for challenging many conventional beliefs so refreshingly. Keep it up!

    June 8, 2017 at 10:27 am
    • Jan Heine, Editor, Bicycle Quarterly

      I’ve always wanted to ride a Paris Galibier. The name and the logo and the amazing frame design…

      June 8, 2017 at 11:23 am
      • Mark Beer

        Well, you’d be welcome to come over and try mine! Next time you’re over the pond perhaps? I won’t try and keep up by the way!

        June 8, 2017 at 12:23 pm
  • Mark Beer

    Recent correspondence with a UK cycling expert (Richard Hallett- rider, journalist, author and frame builder) has prompted me to write again. He points out that any mechanical system which flexes will loose energy (presumably as heat). The point that I have taken up with him, and I would like to make to you, is that we do not produce power in our pedal strokes in a linear manner, however well trained we are. If the frame is viewed as a spring mechanism it will compress with each downstroke, and release the stored energy in the rest of each pedal rotation. This will have a smoothing effect on the delivery of power and feel easier on the legs. Overall energy will be lost but the amount is very small. Over distance therefore the bike will give a more agreeable ride and will perform better as fatigue is diminished. Clearly in a sprint/ track situation every watt lost is unacceptable so flex needs to be minimised. I suspect the concept of “planing” relates to having a “spring rate” in the frame which suits the rider’s power output. Added to this presumably are issues relating to the frame’s natural resonant frequency. This would explain why it is so hard to pin down as one would now need to consider “bike fit” as being well beyond mere geometry. To confound the whole issue power output and cadence will change with fitness/ age etc so a bike that works well one year may not be ideal later. So if you ever reach cycling Nirvana it may not last for long.

    June 10, 2017 at 8:25 am
    • Jan Heine, Editor, Bicycle Quarterly

      I agree, it’s not about efficiency of power transmission. Yes, flex loses energy – but so little that it doesn’t matter. But even in a sprint, many sprinter prefer frames with some flex. If a frame lets you put out 5% more power, then it’s faster, even if you lose 0.01% to heat from the hysteresis of the flexing material. By the way, metal absorbs less energy for the same flex than carbon, so if this was a significant factor, metal frames would be more efficient…

      June 10, 2017 at 1:49 pm
  • frostewistrom

    Perhaps you can also make the comparison to the ski racing world. Any skier who has tried a pair of stiff race skiis know that it takes a hell of a lot of speed and power to make use of it or in fact even be able to turn them properly. Enthusiasts skiers will try to find a pair of skiis that are stiff enough for the terrain that they are skiing but compliant enough to be able to be enjoyed for a full day of fun. Not only a 5 minute race. This range in compliance should be advertised in the cycling world instead of always pushing for the stiffest possible.

    June 10, 2017 at 9:55 am
    • marmotte27

      That’s exactly the point here. Hardly any cyclists are racers yet nearly everyone uses race grade material (even the midlevel frames of today were top notch material a few seasons back).

      June 11, 2017 at 5:22 am
  • gasconha

    I believe that similars discussions are hold among golfers… Steel or carbon shafts?

    June 10, 2017 at 2:09 pm

Comments are closed.

Are you on our list?

Every week, we bring you stories of great rides, new products, and fascinating tech. Sign up and enjoy the ride!

* indicates required