A Journey of Discovery, Part 3: Wide 650B Tires

A Journey of Discovery, Part 3: Wide 650B Tires

How did our preferences change from our familiar bikes with mid-trail geometries, 700C x 28 mm tires and saddlebags to low-trail 650B bikes with much wider tires and handlebar bags? In the first two parts of this series, we talked about discovering handlebar bags and aluminum fenders.
Inspired by the old randonneurs, I decided to ride a tandem in Paris-Brest-Paris 2003. I had met a randonneuse from Toronto, Jaye Haworth, whose strength and souplesse impressed me. Our pedal strokes matched perfectly.
A few months before the event, my friend Hervé found a 1946 René Herse tandem in France. Wouldn’t it be neat to do the event on a classic machine of the type that had been associated with this event for so long?
So far, so good, but the old machine was equipped with wide 650B tires. On the one hand, accepted wisdom said that narrow tires were faster because they could accept higher pressures. On the other hand, in my research for Bicycle Quarterly, I had met riders on 650B bikes completing Paris-Brest-Paris in 50 hours or less, more than 50 years ago. If their bikes were slow, then their leg power must have been superhuman.

The only way to find out was to try it! I borrowed a lovely 1952 René Herse with 650B wheels (above, click on images for higher resolution). Bob Freeman of Elliott Bay Bicycles found some Mitsuboshi 650B tires that he claimed would offer great performance. I was skeptical – they looked like rather ordinary tires to me, with their wire beads and center-rib tread.
I rode the old Herse in our club’s season-opening 100 km Populaire brevet. The season opener was an eye opener as well: The Herse was surprisingly fast. Only one rider, on a titanium racing bike, could keep up. Our time was the fastest over that course so far. Clearly, the wide 650B tires were rolling at least as fast as the medium-width 700C tires that I used on my own bike. (The Mitsuboshi’s center rib in fact was cosmetic only, and not raised like those on many tires offering less performance.) And on the way home from the event, I was pleasantly surprised how little I felt the ridges on the Burke-Gilman Trail, where roots had pushed up the pavement. Speed and comfort, in the same tire!
We did ride the old René Herse tandem in Paris-Brest-Paris 2003. It was a lovely experience that left me (and my stoker Jaye) with a new appreciation for these old machines, and for wide 650B tires.
When Mark and I later tested tires for Bicycle Quarterly, we found that the tires we used on our own bikes actually were among the slower tires, while the wider and more supple 650B tires were significantly faster. Wouldn’t it be nice to ride those tires all the time?
Click here to go to Part 4 of this series.
Click here to start reading with Part 1 of this series.

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Comments (17)

  • Fatmex

    What do you attribute the faster speed of the 650B vs. 700c tires? I would think that top speeds would be greater with the 700c, all other things being equal. Perhaps the relative comfort of the 650B allows better pedal efficiency and less fatigue and thus greater speed over a given distance. But, are all 650B tires equally as comfortable and fast? And, why wouldn’t racers use that size versus the larger 700c?

    February 1, 2011 at 6:52 pm
    • Jan Heine, Editor, Bicycle Quarterly

      The 700C tires we used on our bikes had a relatively stiff casing that absorbed more energy than the supple casing of the 650B tires on the PBP tandem. Our tire tests (Bicycle Quarterly Vol. 5, No. 1) showed that on normal roads, the casing materials and tread thickness determine a tire’s speed more than anything. In those tire tests, the four fastest tires included two handmade racing tires (700C x 24 and 25 mm), a production racing tire (700C x 25 mm) and the 38 mm wide 650B tires. On the other hand, some narrow 700C racing tires were quite slow… We also found that at least up to 25 mm, wider tires definitely are faster than narrower ones. In part as a result of our testing, racers have gone to wider tires in recent years. The rougher the road surface, the wider the optimal tire.

      February 1, 2011 at 7:06 pm
      • Mike

        Given that width beyond 25mm and tire construction techniques are the primary factors behind speed, is there any inherent advantage to 650B over 700C? Assuming the same model tire were available in 700C x 38mm and 650B x 38mm, how would performance differ?
        The larger 700C tire would naturally weigh more. The longer spokes on the 700C may better absorb shock. Perhaps a 700C x 35mm would be the functional equivalent in speed and comfort to an identically produced 650B x 38mm?
        Why does Compass Bicycles sell only 700c tires smaller than 32mm and only sell 650b tires larger than 32mm? Why not sell larger 700C tires?

        February 1, 2011 at 8:38 pm
      • Mike

        Found your response to a similar question in a previous post.

        February 1, 2011 at 8:49 pm
  • MSRW

    Re why racers don’t use 650B wide tires…..my experience (as a former USCF Cat 1) is that randonneuring and road road racing may be different in the sense that the latter is made up of constant explosive accelerations. For that purpose, lighter wheels/tires may work better. There’s an 18 mile loop near my house in Santa Fe that I’ve ridden regularly (solo) at tempo on a 17 lb. Litespeed with Kysirium wheels, as well as on a 34 lb. Surly LHT. The ride is on rolling terrain, has no stops or other delays, can be ridden at fairly constant speed and my times on both bikes tend to be almost identical. However, when I do fast group rides (meaning constant accelerations), it feels like I need to work at least twice as hard on the Surly as I do on the Litespeed. There are variables here that aren’t being controlled (type of tire, bike weight etc); but the main impression on the bike is that those stock Surly wheels with the 700x38C tires are a bear to accelerate quickly. The only research I’ve ever seen that attempted to factor acceleration into tire speed seemed to indicate that it wasn’t a significant variable. I’m suspicious of that since it appears contrary to my personal experience.

    February 1, 2011 at 7:56 pm
    • Jan Heine, Editor, Bicycle Quarterly

      You also have a very different frame on the Surly compared to the Litespeed. Why don’t you put the Litespeed’s wheels on the Surly and go on a fast group ride? If you suddenly can keep up, then you’d know that the bigger tires made the Surly hard to accelerate. If the Surly still doesn’t accelerate well, then you know that the wheels/tires don’t make a huge difference. (It would be nice to try the Litespeed with the wider tires, but I suspect that they don’t fit.)

      February 1, 2011 at 8:01 pm
      • msrw

        Thanks, Jan. The two frames (and any number of other factors) are also different; but aren’t those differences at least partially normalized by comparable times over an 18 mile ride at tempo? (“Tempo” being defined as constant speed ridden at about 80 percent, which in my case averages about 22mph on this route.)
        I guess my question boils down to this: all things being equal, are wider (and hence heavier) tires faster when the riding circumstances involve relatively constant speeds as in randonneuring, but are narrower (and hence lighter) tires faster when the riding circumstances involve constant short sprints and/or other accelerations?

        February 2, 2011 at 7:21 am
        • Jan Heine, Editor, Bicycle Quarterly

          Constant effort and sprints/accelerations are two very different situations. More than once, I found that an overly stiff bike performed fine for me in constant efforts, but was very hard to accelerate. Do the experiment of riding the Surly with the Litespeed’s wheels and report back! I’d love to find out…
          I did a similar experiment – when we tested a Surly Long-Haul Trucker, I put on the Grand Bois 700C x 32 mm tires I usually ride. The bike still felt sluggish to me, and by no means like my own bike, even though the wheels are comparable. But then, the Surly is a touring bike and not really designed for performance, so I wouldn’t complain about that.

          February 2, 2011 at 3:21 pm
  • Lovely Bicycle!

    One thing I’ve been wondering about, is why did the constructeurs themselves eventually switch to 700C tires? There were several auctions in a row of 700C Herse bikes recently, and I kept thinking about this.

    February 2, 2011 at 1:06 am
    • Jan Heine, Editor, Bicycle Quarterly

      You are right, in France, 650B wheels fell from favor during the 1950s among the faster riders. After the Technical Trials ended in 1949, randonneurs began to take their inspiration from racing bikes. Their bikes became heavier, their derailleurs did not shift as well, and their tires became narrower. And of course, narrower tires at higher pressures feelfaster because they transmit higher frequencies of vibration. (When you go faster, the vibration frequencies also go up, because you hit the road irregularities in faster succession.) So everybody felt faster, even though they weren’t.

      February 2, 2011 at 6:50 am
  • Mimi

    Hm, wonder if I could put 650B tires and wheels on my Davidson (built for 700c)

    February 2, 2011 at 10:01 am
    • Jimmy Livengood

      Yes, as long as you don’t have canti brakes. Google “650b conversion” for more.
      Short answer:
      1. new 650b wheels and tires
      2. probably new brake calipers so the pads can be adjusted to reach the rim (19mm lower than 700c pads).

      February 11, 2011 at 12:50 pm
  • BykMor

    Choosing the “ideal” wheel/tire size is always going to be a game of compromise. Large (better ride quality? but at the expense of negatively affecting frame geometry) and heavy; or small (worse ride quality?) and light.
    It’s interesting that the three common wheel tire combinations all share remarkably similar total diameters:
    700cX23 ~ 668mm
    650bX40 ~ 664mm
    26″X2.1″ ~ 667mm
    (Total diameter estimated by BCD +(tire width x 2))
    Modern “29ers” are venturing outside of this sweet-spot with a diameter of ~ 736mm for a ~ 2.25″ tire. Maybe we’ll find that size not to work, but I suspect the benefits of the larger wheel outweigh the downsides in the world of mountain biking. I’m quite happy with my rigid SS 29er.
    Would a TdF racer like a tire with 40c worth of air if it didn’t weigh more a few grams more (significant, I’m sure, to a racer), produce more aerodynamic drag and be break the UCI’s rules? Would Jan like a 622 BCD wheel with 40c worth of air on his randonneur if it didn’t start to really mess with the geometry? Would everyone be happier with a 20″ wheel if it could handle the road/trail sized obstacles (chip seal to curbs to tree stumps) that we need to be able to handle? We’ll probably never know since physical compromises will always prevent the world from being perfect.

    February 2, 2011 at 2:37 pm
    • Jan Heine, Editor, Bicycle Quarterly

      We tested three bikes that were identical except for the wheel size, and found that the handling was quite different. Depending on the tires we mounted, we either preferred the 700C bike, the 650B bike or the 26″ bike. We calculated the gyroscopic stability of each wheel/tire combination, and found that our preferences fall into a relatively narrow range.
      Coincidentally, over the last 120 years, bikes constantly have gravitated toward that range. Many have tried larger or smaller wheels, but in the end, the table you show above has remained valid. Tire/rim weight also factor into gyroscopic stability, so a heavier tire should have a smaller outer diameter than a lighter one, if you want to keep the handling the same.

      February 2, 2011 at 3:25 pm
  • Iron Rider

    My hypothesis is that the switch to 650b makes the same bike seem to ride “faster” because it effectively changes the gain ratio. Changing to a smaller wheel results slightly reduces the gear ratio (and gain inches) through the whole range of the gearing. (Check out Sheldon Brown’s gear calculator and see for yourself by inputting your current gears and switching wheel sizes.) As a result of the new gear ratio, the rider experiences reduced pedal resistance at each gear. Lower pedal resistance means that keeping your best cadence becomes easier and shifts your efforts toward slow twitch muscles. In short, switching wheels, like changing cassettes, makes it easier to spin. For amateur riders, reducing pedal resistance is a way making the bike seem “lighter” and “faster” so whether it is done by changing gears, changing cassettes or changing wheels, would not really matter to your legs, as long as it works.

    February 6, 2011 at 12:14 pm
    • Jan Heine, Editor, Bicycle Quarterly

      You make a good point. This also means that if you put wider tires on your bike, it will be harder to pedal in the same gears, because you are going faster with the larger wheel diameter.
      However, the faster times I rode on 650B bikes were measured with stopwatches. That said, I want to make it clear that 650B tires are not inherently faster. In our tire tests, we compared the Grand Bois Cypres 650B x 32 mm with the same tire in 700C x 32 mm, and the speeds were indistinguishable. Back when I first rode 650B, I was comparing a wide, supple tire with a narrower, not-so-supple tire…
      The main reason to ride wider tires is that you can get added comfort and the ability to carry your speed over rough roads without giving up anything on smooth surfaces. And we chose 650B because it offers the best handling with wide tires.

      February 6, 2011 at 1:42 pm
  • Willem

    As I said on other occasions, I think all of this makes perfect sense. One of the consequences is that for more loaded touring over sometimes rougher terrain, 559 is the ideaal size as it allows you to use heavier and wider tyres that can still handle nicely. I think for most uses 50 mm is the ideal width in 559 tyres, and even though the choice is already enormous, and for a great variety of conditions, it would still be nice to have a 50-559 Hetre as well.

    February 8, 2011 at 11:13 am

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