A Rad Rod Retrofit: My Firefly 2.0 Chubby Road

When I began working with the team at Firefly on my first disc brake road bike back in 2014, I wanted it to be perfect. The problem was at the time, the industry was very imperfect when it came to disc brakes on road bikes and all the accompanying standards. That was three or four years ago. Flat mount wasn’t on the table, many road forks used a 15mm thru-axle, and SRAM’s 1x XD driver had just switched to the road market after a successful introduction into the MTB market years prior. Trying to figure out the specs on this bike took a lot of back and forth for both me and Firefly. I wanted this bike to be perfect… this is, after all, a dream bike!

Since getting the Rad Rod in 2015, I’ve had this bike built up a number of different ways, traveled the globe with it, toured on it, and came to the conclusion that I truly do love it. So when Tyler emailed me, asking what I’d think about sending it back for a retrofit, I was intrigued.

His proposal was a rear-end retrofit, with a new Firefly thru-axle dropout but most importantly, a new 3D-printed titanium yoke that would allow for a large tire and the use of a 2x drivetrain. By this point, I’d ridden a number of other drop bar “all road” bikes, but really wanted a straight up “chubby road,” or a disc brake, 650b, 2x road bike.

So what did Firefly have to say about this process? Read on for two quotes from Tyler regarding their new yoke and how it applies to this retrofit.

About the Yoke
“We designed our 3D printed yoke specifically for pairing a road compact or sub-compact cranksets with 650b and 700c high volume tires and the shortest possible chainstay lengths. Depending on the exact geometry and component specifications, the yoke allows us to build in clearance for up to 700c x 44mm and 650b x 2.1” tires.”

“While running a single chainring does have some advantages in terms of simplicity, in most cases we have found that a 1x drivetrain lacks the fidelity in jumps between gears that an All-Road Bike demands. All-Road bikes for most of our customers and ourselves are ridden on highly varied terrain that covers many small changes in gradient and speed. The smaller jumps between gears with a 2x drivetrain make it easier to find the right cadence on that terrain. We have found that 1x drivetrains are best suited to more extreme off-road bicycle platforms (i.e. MTB or Cyclocross) where that delicacy isn’t as crucial.” – Tyler Evans, co-owner of Firefly Bicycles

About the Retrofit
“When initially suggesting this project we thought this retrofit might be a viable option to offer our past customers as an upgrade to their current bike. But we quickly learned that, in reality, this is not a cost-effective or efficient option. The labor hours involved are equal to or even exceed that of making a frame from scratch. In essence, as an upgrade, adding this part to an existing bike is cost prohibitive, but it was a fun side project, totally worth doing, and we learned a lot.” – Tyler Evans, co-owner of Firefly Bicycles

Rad Rod Volume 2

I have a drop bar bike that I love to ride on singletrack, I have a classic rim brake road bike that I’ll take on paved roads, and now I have a disc road bike that I’m comfortable riding dirt roads, and the paved roads that are in between my apartment and the mountains. Sure, there’s a ton of overlap here, but I love bikes and am methodical about their uses. For this build, I wanted a 650b disc road bike with plump, 47mm road tires.

For the build kit, I’ve had great luck with SRAM Rival 22 in the past. It just works. The White Industries R30 cranks have also done me well, plus they look great and are made in Petaluma, California. My friends at GSC and Sim Works had a new bar out that I really wanted to try, too! Those were my known go-to parts, what was the unknown were the wheels. I would be more than happy with my older WTB wheels which this bike confidently rolled on prior, but around the time of this retrofit, Zipp offered up a set of their new 650B Zipp 303 Firecrest wheels. The Teravail Rampart tires are perfect for the kind of riding this bike would be undertaking.

About Those Wheels

Zipp’s quality, reliability, and construction need no introduction, what I was interested in finding out was how a 45mm road wheel in a smaller diameter would feel. I’m not one to fall into the aero marketing trap, but I do like wheels that are optimized for fatter tires, which set up easily tubeless, require little to no maintenance and look good. The 303 Firecrest design and engineering are on par with what you would expect from Zipp. They feel great on the ups and are fun on the downs, with very little noticeable “wind walking” during breezy or windy days.

It’s hard to review wheels, especially when they’re literally some of the best you can buy. The problem is, there are many options out there for just such a wheelset and many of those options won’t cost $2,500, but Zipp’s rims are made in the USA and are backed by a two-year warranty. My one main complaint is that it’s hard to find a 650b tube with a long enough valve stem to carry as a spare. For now, I have a spare tube with a valve extender. The difficulty in reviewing wheels like this is finding something to critique! All I can say is going from a 32h wheelset to lightweight, 24h, wheelset resulted in a noticeable “spryness” feel to what I would consider my most familiar bike. See more information at Zipp!

A Work in Progress

Much like this bike’s inspiration – a chopped and altered rat rod car – the Rad Rod shows use, not abuse, and now has a new found face as a 2x chubby road bike. The bike’s fit and build are perfect for dirt road rides in the mountains that surround my home in Los Angeles and beyond. I’ve already been putting more miles on it and with each ride, it puts a huge smile on my face.

Got any questions? Drop them in the comments!

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Read more on Firefly’s technology at their website and Follow Firefly on Instagram.

  • Kerry Nordstrom

    I faced the same constraints and quizzical looks in 2013 when designing my Seven, which you saw prior to owning this bike and I wonder if it helped inspire the Firefly ; ) . Given my original intent for a thru axle, reasonably fat-tired “all-road” bike, I’d love to do a similar retrofit someday and wonder if Tyler would consider doing it to other frames than just Fireflies!

    • A lot of bikes inspired this one. I was scouring for all kinds of titanium disc road bikes, but the Stiggy inspired this bike the most. I liked how it had a road geometry in a ‘cross package. Firefly won’t do retrofits – he goes over why in his quote above – but in short, it’s too cost prohibitive. They just picked the Rad Rod because it was iconic and they knew I was pushing for something like that when it was designed…

  • Dr J

    Such a beautiful bike! Just curious – what’s the chainstay length that requires a yoke to fit 650Bx2.1″ tires?
    Makes me glad I waited until last year to have my custom 44 built. I avoided all headaches with these “incomplete standards”.

    • the chainstay is 420mm. It’ll fit a 700x45mm tire too!

  • bicyclecrumbs

    dem Zipps are legit!!! There is a reason we’ve been spec’ing them. Also the ease to set them up tubeless is mind blowing compared to the struggle ive had with my weak ass computer hands and other tubeless rims. With ARs if i get a flat i might as well throw the bike in the nearest dumpster because theres no way I can get that tire off.

    • Ha! Yeah, I actually re-seated these with a floor pump believe it or not.

  • Daniel Smith

    I know this is my favorite of your personal bikes, but it may be one of my favorite ever on the site! Didn’t you have Easton EC90sl cranks on this bike? I would think they would be perfect to transition from a 1x to 2x setup with their cinch system.
    Anyway, I love to see such great Ti goodness! I hope to join the club someday…

    • Yeah, I had the Easton cranks on it, but wanted to put the White cranks on, mostly for aesthetic purposes but I also love the way they feel.

      • Luke Heerema

        John, what do you mean by “feel?” Wanting to justify a purchase here!

        • I just like the way a 30mm spindle on a thinner profile aluminum crank arm feels. It’s hard to explain, but I find carbon cranks to be too harsh. Too stiff.

          • Daniel Smith

            Does this bike have a press-fit BB? I would’ve taken you as more of a threaded kind of guy ;)

            In my daydreaming about a future Firefly build, I’m curious if they can do a t47 bb.

          • It’s a threaded BB.

  • You didn’t mention the upgraded seatpost collar ;). Looks good, man.

  • Peter Hedman

    Nice work! Tyler is great dude, I had some great interactions with him back in the IF days. I love seeing how Firefly has progressed and the tasteful (not overdone) use of 3D printed bits is a really nice touch.

    No surprise he isn’t offering this as a service. Having done my fair share of dropout swaps and frame repairs, these kind of retrofits are a major PITA. In fact, I’m kind of surprised he did this one for you!

  • 1. That yoke is real nice. A great application for 3D printing.

    2. Was this bike the beginning of the “John Prolly: Fifty Shades of Brown” series?

    3. You know I’m with you on the Rival 22! I personally prefer the ergonomics of the mechanical hoods, but the hydro brakes are easy performance out of the box.

  • nothingfuture

    I’ve always like that bike- that it’s current build is just as lovely.

    Someday, I’d like to build up a 700c based chubby road bike (I’m 6’1″, ride a 60cm, and feel like 650b would be a little small, proportionately- but I’d be open to a discussion). Hydro discs, 2x… this bike, essentially.
    I guess I’m saying I’d like to buy a bigger version of this bike at some point.

    • I’m 6’2″ with a 32″ inseam and 27.5 feels great to me. But it’s all preference.

      • Do you ever feel you want a 700c, say with a 35mm, on more road based ventures that will still have some dirt in there. I don’t know, say 70-80/30-20 road/dirt? I’ve not directly compared my bike 650×47 v 700x(say)35 so not sure how much difference it might make in the riding – particularly on the road bits (probably splitting hairs etc, but as you said about the bike overlap… why not discuss) Cheers.

        • I don’t find that, no. Even if I ride this bike on 100% pavement, our roads are so fucked up that I like the higher volume tires.

          • Patrick Jonathan Neitzey

            Best thing about chubby roads/groad/chode bikes to me is simply riding on god awful roads with greater comfort

          • Chris Valente

            lol chode bike

          • cheers John, saves me buying another set of wheels going along with your thoughts. More coin for adventures. To be honest, it would be a daft buy as most rides are 80/20 or more dirt/road so 650/47 is always the go to anyway.

        • AaronBenjamin

          I have done many off-road rides on loose dirt on 700x35s and they are more than adequate. What you get with the smaller size tire is a bit more cush and a bit more nimbleness.

  • Heffe

    Slightly off topic – have you ever gotten back to us on the I9 disc wheelset that you were going to test a few months ago?

  • Alexander Putz

    @johnprolly:disqus
    what size chainrings are you running on this rebuild, John?

    • 48/34, same as my Speedvagen road bike with a 32t cassette. Makes some of my steep mountain dirt roads hurt a bit more but that’s a good thing, right?

      • nothingfuture

        I’ve been told “pain is weakness leaving the body” but I’m not sure I believe it.

  • Peperbek

    “While running a single chainring does have some advantages in terms of simplicity, in most cases we have found that a 1x drivetrain lacks the fidelity in jumps between gears that an All-Road Bike demands”
    Current product managers will probably deny this but I couldn’t agree more.
    Love this bike!

    • I’m not 100% in agreeance there. For me, it’s more about the terrain and ease of shifting. I feel like on dirt, you’re more likely to shift around the cassette more than on a sustained road climb. Things like noting the jumps between gears are something I’ve never really noticed before. Only in Eagle where you go up to the 50t.

      • W. Bradford Williams

        What say you re: those cranks and double chainrings? Happy? I like those cranks but am also tempted by the Easton’s for a similar bike I am working on.

        • They’re just completely different. I wanted to go for a classic look with this build.

  • Joey Sikorski

    I’ve looked at this album like 3 times today. Fricken beautiful!

    • Love your avatar! That guy was really friendly. :-)

      • Joey Sikorski

        Haha! Man, I didn’t even realize that. Long story short, I was looking over that trip on my shop computer the other day and a co worker decided to make him my profile picture. Defiantly wasn’t trying to steal any pictures haha.

        • Oh I don’t care! That’s why I put them up here.

  • Frank

    Nicely played Firefly.
    Mark of Prova Cycles (in Melbourne) does a similar 3D printed yoke in steel for similar results on his dreamy Mostro bike.

  • Brent Kyono

    Possibly my favorite bike of yours, or perhaps tied with the Crema :) Big tires forever!

    • Yeah, this is all-time for me for sure!

    • Thad Hoffman

      That Crema is my fav bike of John’s as well. 650b Dropbar Stinner of Kyle’s collection too. This Rad Rod is up there in the #2 spot for me. Definitely would ride either of them happily.

      • The Crema is no longer mine, unfortunately. I had to cull my belongings – trying to minimize my bike collection and stoke some friends out with some sweet rides for cheap.

  • DaveB

    The new to old Ombré is so sick! SUCH a nice bike !!

  • Definitely a favorite here. Probably the best in your quiver, and so cool to see it get even more life and adapatability out of it with the retrofit.

    • Agreed! This and my Retrotec are longtime favorites.

  • Tom Bassett

    Special shout out to the chain hanger. It’s the little things…

    • Bas

      I noticed and loved that little detail too!

  • An awesome rebuild of an awesome build. Love it. Did you have a matching camera bag made for your bars?

  • Tom Greek

    Love this Bike John. That rear triangle is just beautiful. Have been toying with a double setup on my moots for a while – but keep coming back to the single as the way to go. When I’m with other folks running a single chainring, or by myself it’s perfect. When on a mixed ride that includes a bunch of road with folks running a double – I miss the tighter gear selection. I feel like I’m spinning too much or pushing too hard a gear on climbs. Thought about a cross double and a 36t cassette. Don’t know if it would work, if the steps would still be too big, or if I would just miss that 42t cog too much! May have to pick your brain about the gearing when I bump into next!

    • AaronBenjamin

      You are thinking too hard. Throw a 11-36T on there, GX 10 speed RD and pedal harder.

  • Going to sell the WTB wheels? :)

  • Sattelfest

    so 650b x 2.1 will fit?

    • Sattelfest

      drawback..the bombtrack hook ext has “only” clearance for 46/36t.

  • Jake Hueber

    What do you think of these Teravail’s compared to the WTB’s you’ve used in the past? Oh and amazing looking bike, one of my favorites on the site.

    • I’d say they’re both very similar. Blind test, I wouldn’t be able to tell the difference.

  • AaronBenjamin

    Ha! I knew gravel bikes were going back to 2x systems before long. A clutched derailleur would go a long way in handling the extra chain length.

    • This isn’t really a “gravel bike” – more of a road bike. My Sklar is a “gravel” bike.

  • Tyler Johnson

    I love the way this came out! I want to do the same type of retrofit with my Wraith Disc that Adam made me. Looks good!