A Firefly for Vermont’s Class IV Trails

A Firefly for Vermont’s Class IV Trails

There are some bikes that you see on social media, and you just want to know more. FF986 popped up on the Firefly feed a little while ago, and it just looked so dialed. You could see that every part was carefully considered, chosen for the riding that the rider intends to do. In Vermont, Class IV designates roads and trails that aren’t maintained. They criss-cross the Green Mountain State and make for great adventures. Here’s what Kevin from Firefly told me about this project:

“We designed and built FF986 for a highly skilled and very strong rider in Northern Vermont. He wanted the bike to be capable year-round on everything from pavement and smooth dirt to the roughest Class IV trails VT has to offer, and comfortable for regular long rides of 150 miles or more. He also came into the process with extensive experience on other bikes, including a number of frames he had built for himself.

“That level of experience is never necessary, but it made for a particularly collaborative frame design process with a lot of specific personal touches. We built it with massive tire clearance for up to 650×2.3″ tires with fenders, compatibility for 1x and 2x drivetrains, internal dynamo light wiring, three bottle cage mounts, bolt-on top tube bag mounts, a pump peg and matching Ti Silca Impero pump, and lots of mounting options on the Steve Potts fork as well.”

I can only imagine how involved a build like this is. There are lots of details that need to be just right. And this bike really came together nicely. I love the thru-axle steel fork with the clean generator hub installation. The wiring is especially neat. The SON Delux hub is laced to carbon Enve rims.

The Rene Herse taillight is mounted on a custom-made titanium boss. The wires run inside the frame.

The Edelux headlight connects to a splitter box, so phone, GPS and other devices can be charged from the generator hub while riding.

The fenders are the new ultra-wide Rene Herse H-98, mounted with ample clearance above the 650B x 48 mm Juniper Ridge Extralight dual-purpose knobbies. The second stay in front of the fork crown stabilizes the fender – essential for fast riding across rough terrain.

I love the contrast between space-age titanium and the leather washers to mount the fender. Why leather? Because it does an excellent job at keeping vibrations from loosening the fender. And unlike rubber or plastic, it doesn’t crack even after decades of exposure to the elements. There are lots of other details here: the tunnel for the brake cable/hose, the titanium cranks and Firefly’s super-clean welds.

The fenders, pump and fork crown are painted. They provide a nice contrast to the raw finish of the titanium frame. It’s quite different from the elaborate anodized finishes of many Fireflies, but no less beautiful.

The drivetrain uses titanium eeWings cranks with an oval chainring, plus a custom cage on the Shimano GRX derailleur.

Despite its wide tires and massive fender clearances, the bike doesn’t look ungainly. Leave it to Firefly to create a bike that’s nicely proportioned and finely crafted! I love how they create bikes that reflect their owners’ tastes and preferences, yet they are all tastefully done.

The best part is that this isn’t a show bike. The rider wrote to Firefly just over two weeks after receiving it: He had already ridden 1000 miles on his new bike. Imagine this bike flying over Vermont’s gnarly Class IV roads! It makes me smile, and I’m sure it did the same for the Firefly crew. Well done!

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Comments (48)

  • Chris

    Pretty, but it seems to me that the taillight is hard to see from a car behind, as it is covered by the rear fender?

    March 3, 2021 at 6:32 am
    • Jan Heine

      Unless it’s a Ferrari that follows you down a Class IV road 😉, the taillight will be visible. It looks like the centerline of the taillight is even with the fender top. Most cars put the driver’s sightline quite a bit higher than the 700 cm diameter of the bike’s wheel, so drivers look slightly down onto the taillight, even from a distance. So it shouldn’t be a problem – just one of the many things to consider when building a bike like this.

      March 3, 2021 at 8:39 am
      • Sam K

        On hilly roads, I wonder how the gradients affect the visibility of taillights like this.

        March 3, 2021 at 8:46 am
        • Jan Heine

          On hilly roads, the rider is hidden when they’re in the dips. So are cars – and trees that have fallen on the road. This happens during daytime or at night. There’s nothing you can do about it, but everybody knows about it and looks out carefully. There’s little danger that you’ll get hit by an inattentive driver on a hilly, curving road. They have to be attentive just to stay on the road…

          When you’re on backroads in the mountains, the headlight beam of a vehicle in front is far more visible than the taillight, both for bikes and cars. The taillight is almost superfluous there. You need the taillight in the city, where there’s so much light around that you can’t even see the headlight beam as the rider/driver. (That’s why people tend to forget turning on their lights when they drive in the dark.)

          I once organized a brevet and drove along the course after the riders had started. On the curving mountain road, I was surprised how visible the cyclists were compared to daytime, where everything blends into the scenery. And passing the cyclists was easy, too, since I could see the headlight beams of oncoming cars long before they came around bends. So I’d say that barring drunk drivers and self-inflicted accidents (which can be avoided through careful route planning and riding within your skills), riding in the mountains is even safer at night than during daytime.

          March 3, 2021 at 8:57 am
          • Andy Huang

            It’s an interesting point that cyclists might be safer on challenging roads because the drivers will be more attentive. Until the recent fatalities in Nevada my judgement had been that long clear sightlines would make sure motorists would know you were there. But that’s countered by the tendency to go on autopilot on boring roads.

            March 3, 2021 at 9:47 am
          • Jan Heine

            The braking distance of a modern car is so short that most of the problems come from inattention, not from problems seeing cyclists far enough in the distance. Actually, most accidents occur at intersections, but that’s a totally different matter altogether…

            March 3, 2021 at 6:59 pm
      • cyklev

        Yeb, Jan good reply. I use a similar position for the rear light and its totally fine. @Chris: But seeing this bike product photo from this perspective, it seems that the light is hard to see. Once you’ve seen it live in action, you’ll be convinced. 🙂

        March 3, 2021 at 1:35 pm
        • Daniel

          It looks like great rear visibility. As a commuting in an urban area, I worry more about side visibility especially at intersections. I have two rear lights, one on my rack and one on my fender (yes it is exposed but is secondary lighting) and I also use lit reflectors on my wheels for side visibility. I’m pretty sure all of that is unnecessary on this bike, which is beautiful as is. I’m unlikely to ever be able to afford a Firefly but I can still wish I could.

          March 4, 2021 at 8:45 am
          • Jan Heine

            Safety is a big concern in the city, and being visible is a big part of that.

            However, whether you are visible from the side isn’t a problem. You are moving forward on your bike, so if somebody hits you from the side, it’s because they did not see your front light as you were approaching – unless you stop in the middle of an intersection. Wheel reflectors look impressive from a distance, but they don’t help prevent accidents: By the time the car (or other traffic) arrives from the side, the cyclist is already gone. Look at cars: In most countries, they don’t have any lights on the sides, but they don’t get T-boned more often than American drivers (who have very small ‘sidelights’).

            March 4, 2021 at 9:51 am
    • Dietrich Martin

      I do agree with you. Even though the back light looks nice and safe in this spot, but visibility is a must. Backlights belong to the far rear end. Also consider line lights, which make judging distances for the vehicles following much easier than just a point/dot/spot.

      March 3, 2021 at 12:37 pm
      • Jan Heine

        Interesting thought… Placing the light further back will put it closer to the approaching car, but the difference is only about 1% (50 cm for a car that’s 50 m away). On the other hand, a light on the back of the fender is much more prone to damage… which means no light at all.

        March 3, 2021 at 7:05 pm
  • s.e. charles

    good onya to be showing some east coast love!

    March 3, 2021 at 6:41 am
  • Harris

    It’s perfect. Vermont has the best all-road adventures in the world, I’m sure of it. For years we converted any bike with suitable BB drop to 650b to squeeze every millimeter of 38 and 42c tires that were available at the time to better enjoy these conditions. I can’t tell you how amazing it has been to witness the evolution of all-road products that actually suit the kind of riding we do. Three cheers for Vermont’s class IV roads! Three cheers for Firefly! Three more for Rene Herse! Hip hip Hooray!

    March 3, 2021 at 6:47 am
  • wfstekl

    Oh my gosh, this machine is sublime, gnarly and purposeful. A trifecta.

    March 3, 2021 at 6:50 am
  • Darrell Roberts

    My list of dream gravel bikes is long but a Firefly has remained at the top of the list. Reading about this bike puts a Firefly even further out in front of all the rest!

    March 3, 2021 at 6:56 am
  • Michael

    how much does this bike cost as shown?

    March 3, 2021 at 7:04 am
    • Jan Heine

      Ask Firefly! I’m sure it’s not inexpensive, but considering how much the rider will enjoy it – he’s already ridden it thousands of miles – the cost-per-mile will be quite reasonable.

      March 3, 2021 at 8:41 am
      • Colin Cox

        “Cost per mile”. I’m using that next time when mansplaining the cost of a new bike to my wife.

        March 3, 2021 at 1:05 pm
        • Jan Heine

          The most expensive bike I’ve ever owned was a $ 750 Peugeot I bought in high school. I rode it for 5,000 km and two years, but in that period, it needed to have almost every part except the frame replaced. Fortunately, I was able to sell it before it cost me even more… The next bike cost 3x as much and lasted without major repairs for 10 years and 100,000 km.

          March 3, 2021 at 7:07 pm
        • Stuart Fogg

          My wife might come back with “cost per minute” for putting up with me and my bike.

          March 5, 2021 at 11:37 am
  • Monty Richardson

    Absolutely stunning!

    March 3, 2021 at 7:04 am
  • Paul Richard

    If one were using Humtulips 26 x 2.3 knobbies, what fenders would be best?

    March 3, 2021 at 7:06 am
    • Jan Heine

      Use the same Rene Herse H-98 fenders, only in a 26″ size.

      March 3, 2021 at 8:15 am
  • Chris Grigsby

    Hit me up if you ever want to feature my new Nobilette 650b randonneur that is literally dripping in Rene Herse componentry. It was commissioned in early March of 2020, mere weeks before the world turned upside down.

    March 3, 2021 at 7:12 am
    • Jan Heine

      Mark’s a great builder! Enjoy the bike!

      March 3, 2021 at 9:34 am
  • James P Thurber

    That’s a spectacular bike. Points to ponder: The Steve Potts fork – gorgeous. The one-by drivetrain? A perfect (and very reliable) gear set. Three bottle holders? Two for water, one for diet coke (Pepsi please). One definite note – the shifting is NOT electric. Hmmmmm?

    OK Firefly, are you ready to build one for me?

    March 3, 2021 at 7:22 am
    • Kyle Hollasch

      While not nearly as fancy, it’s nice to see that my Rawland Drakkar from 2010 – which I run with either 700×44 or 650Bx2.2 (each with their own unique fenders) – was way ahead of its time.

      March 3, 2021 at 10:07 am
  • David

    Any idea on the weight, as shown?

    March 3, 2021 at 7:33 am
    • Jan Heine

      My guess is about 10.5 kg (23 lb). Disc brakes add weight (and so do lights and fenders, of course), but the butted titanium frame is light. It also depends on how many bolts there are to attach fenders and lights, as those add up quickly…

      March 3, 2021 at 8:34 am
  • Joe Maki

    What a beautiful bike!

    It’s too bad they didn’t internally route the headlight wiring also

    March 3, 2021 at 7:41 am
  • jon norstog

    This is basically the bike I built for the Oregon Outback, but in 853 instead of Ti, right down to every bottle mount I could fit on the frame. Convergent design!

    March 3, 2021 at 8:30 am
  • Grant

    Those mudflaps make me drool, and are probably just custom enough that I can’t buy or make them myself lol

    March 3, 2021 at 8:58 am
    • Jan Heine

      Those mudflaps are neat. They are easy to make, though: Make a cardboard pattern that fits between the rolled edges of your fenders. When you got it perfect, transfer to the material of choice. I use thin rubber sheet that’s available in hardware stores to make your own gaskets. The only tool you need are scissors.

      March 3, 2021 at 9:04 am
  • Paul Ahart

    What an amazingly well thought-out bike. I especially like the lighting and the wiring that so well allows for charging of accessories we never dreamed of a decade or so ago.
    The input into it’s design and execution by the very experienced rider, working with the people at Firefly, really shows. Pretty much perfect in all ways.

    March 3, 2021 at 10:03 am
  • Andy Stow

    Gorgeous! I know how I’ll spend some of my “extra” money once my sons are out of college in a few years.

    March 3, 2021 at 11:30 am
  • kai s

    so finally wide rims. i know you have been a skeptic Jan, but your future:) tests will show rolling with a given (appropriately wide) tire will improve, as well as stability at low pressures.


    March 3, 2021 at 11:45 am
    • Jan Heine

      Wide rims are probably stronger and may also be more aero with wide tires (although it seems that you can also get an aero shape with a narrow rim if you include the tire in the teardrop shape). If you like wide rims, there are plenty of options. We even offer them in the Rene Herse program.

      However, I’m not convinced that more vertical sidewalls offer advantages. You’ve probably read about it in this post… and nothing has really changed since then.

      March 3, 2021 at 7:03 pm
  • Paul

    Glad to see the wiring on the dynamo hub has been upgraded from the 1870 Edison version.

    March 3, 2021 at 12:56 pm
    • Jan Heine

      Now we only have to get rid of the archaic chain drive! 😉

      March 3, 2021 at 7:11 pm
  • Sarkis Benliyan

    Great looking bike. It’s almost too good to be true … Regardless of the cost per mile that Mr. Heine mentioned earlier, this bike is out of reach for most people. The acquisition costs alone. But hey .. isn’t that just “bike porn”? An object of desire for middle-aged men whose libido is slowly waning? Fun aside: But honestly: A steel wheel with half the bling and without adamantium or carbon components does the job too. Innit?

    March 3, 2021 at 1:39 pm
    • Andy Stow

      It’s either transportation or a toy.

      If it’s transportation, it’s probably comparable to a nice three year old used car, and less than the cheapest new car.
      If it’s a toy, I know plenty of blue collar workers with $25,000 Harleys they ride on the weekends only. Or bass boats, ATVs, snowmobiles, Sea Doos…

      March 4, 2021 at 7:45 am
  • Willy Varley

    Beautiful machine. Just one question, I know Jan does not like rear racks, and I see this frame has no braze on for a rear rack. I just wondering on a brand new frame it would be easy to add a few bold holes for the future.

    March 3, 2021 at 6:31 pm
    • Jan Heine

      These bikes are custom, and Firefly will gladly put rear rack braze-ons on a bike they build for you!

      March 3, 2021 at 7:11 pm
  • Derek

    So many comments about the tail light, yet no one mentions that the headlight is obviously aimed way too high?
    It may help see farther ahead in some situations, but that’s not a good enough reason to have it pointed up in the trees, or other peoples’ eyes, the rest of the time. Very easy to fix, but a glaring mistake none the less.

    March 4, 2021 at 12:17 pm
    • Jan Heine

      Actually, the headlight is aimed correctly. The SON Edelux has the best beam pattern and highest quality (no plastic mounts that crack when riding fast on rough roads), but it uses a reflector that’s intended for city bikes and riders who want/need to illuminate only the 10 meters (30 ft) in front of the bike. Going faster, you need to see much further than that, and on rollercoaster Class IV roads, you also need to be able to see ahead when the bike is heading into a small dip.

      The solution is a light mount that allows adjusting the beam angle by hand, yet keeps the bolts tight – like our Rene Herse light mounts. That way, you can lower the light a bit when you’re on roads where the is oncoming traffic, so you don’t blind anybody, but raise it when you’re on challenging roads by yourself. However, the light always will point slightly upward. That’s just how it’s designed.

      March 5, 2021 at 7:46 am
  • Bill

    It’s interesting and unusual for me to see knobbies with fenders. While I love the way my RH knobbies perform on the gnarliest Vermont dirt roads, I’m hesitant to ride them with fenders. Do you have any sense of how well the knobby/fender combo performs on a muddy road in a heavy rainstorm, or on a jeep trail strewn with fallen branches? This bike appears to have great fender clearance (about 30 mm?). How much should I worry that the mudflap will scoop up tree fall or the knobbies will clog my fenders with mud?

    March 5, 2021 at 7:48 am
    • Jan Heine

      Knobbies and fenders require extra precaution. As you noted, Firefly build the bike with very generous fender clearances. That’s essential, because then most debris will either go through or it’s so big that it’s too heavy to accelerate much and hit the fenders with great force. Also, the H-98 fenders are large and very stiff. They are made from slightly thicker aluminum, so they’re unlikely to collapse like pastic fenders if they’re hit by a stick.

      Of course, all depends. There is mud and there is mud. Some mud clogs up even a fenderless ‘cross bike until the wheels no longer turn…

      March 5, 2021 at 8:50 am
  • Mark Guglielmana

    I can’t find a single thing I’d do differently on an “all in” go anywhere bike outside of a front handlebar rack, but that’s just a personal choice. I’m really happy that fenders are integrated in the design, they’re usually an afterthought on gravel bikes. It appears that tire clearance is in the 25-30mm range, plenty of room for the larger chunks that one picks up on the roads it was designed to go on.

    March 5, 2021 at 9:52 am

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