I’ve seen a lot of people dismiss 650b conversions on vintage 26 inch frames, but I wanted to share why it was the perfect solution for me.
The Backstory: I already had a pride and joy bike, but after sinking a ton of money into it, I realized I was terrified to leave it locked up at the grocery store. I wanted a steel, drop bar, upright commuter/road bike, but a new build would just be another theft magnet. Then I saw u/phatsackocrap's converted Antelope. By total luck, I found a color-matched 1990 Trek 850 on Craigslist that same day for 80 USD. The bearings were grinding and it was rough, but the frame was solid. It was meant to be.
The Build Strategy: Since the rear spacing was 130mm, finding pre-built tubeless wheels was a nightmare. I figured if I had to lace my own wheels anyway, why not go 650b? Wheels: Velocity Cliffhanger rims laced to Shimano 105 hubs. Brakes: Shimano BR-CX50 Cantilevers. These have just enough vertical adjustment to hit the 650b rim track perfectly. The Tire Gamble: I went with Ultradynamico Cava race tires (650b x 47.99). I’ve seen mixed reviews—either buttery smooth or instant sidewall slashes. The Fit: On 25mm internal rims, they stretched to 48.5mm. Clearance: I’ve got about 5mm at the fork. Tight? Yes. Functional? Absolutely. The Ride: I’ve put 100 miles on everything from smooth pavement, to chunky railroad ballast, to flowy singletrack. If you aren't smashing into every rock and actually pick a line, these tires are quiet, grippy, and incredibly supple.
The Vibe: The final touch was some glow-in-the-dark mushroom stem caps a friend picked up for me from Mad Monkey Designs. They are silly, cheap, and add some great flair. This bike is now my everything rig except when I want to get more intense mountain bike trails. It is fast on the road, capable on the dirt, and while it looks rad to those who know, it is still just an old Trek to the average bike thief. Anyone else rocking a 650b converted 26 inch bike? Are you happy with the decision?
I'd also welcome any feedback or criticism. This is only my second bike build and I am sure I still have a lot to learn.
edit: fixed a couple typos.
by qualitycensorship
14 Comments
The main reason I don’t think it’s worth it is because 650b is sadly falling out of favor, with fewer rim and tire options as there were a few years ago. Granted, it’s still better than the 26″ offerings, for now, but I wouldn’t invest in it for a single bike. There are definitely more rim-brake rims in 26″ than 650b rims with rim brake tracks so that makes me hesitant.
There’s also the question of whether your brakes will reach properly. Nice to know the CX50 will work here.
I’m surprised you didn’t just cold set the frame out to 135mm.
I’m in a similar situation and can’t make up my mind. I have a Gary Fisher Aquila that I pulled out of the trash. The fork needed rebuilt and isn’t well received for heavier riders anyway so I just replaced it with a rigid fork (Potts). The front is going to be disc brake which means 650b or 26″ are equally good options. If I go 26″, then I need to build up a wheel, as it’s also thru axle and that’s an odd ball combination. If I go 650b, I already have a front wheel that I can use. I’d rather keep both wheels the same and not run a mullet. So it really comes down to, would I rather build up a 650b rear wheel or a 26″ front wheel. The upside of the 650b route is that I can swap it between more bikes.
I think the reason people are critical of 650B conversions is that it’s a hack without clear benefits. You’ve outlined the possible downfalls in your post – Clearance, brake reach, need to build up your own wheels. What are the upsides here? You end up with a build that requires a specific combination of parts to essentially achieve the same function as running run of the mill cantis with widely available 26 inch wheels and 26 inch Gravelking Slicks with tubes.
Don’t get me wrong – your build is awesome and looks super sick, building your own wheels rules and if you want tubeless (as you said) you’d need to get new wheels anyway. But people are IMO rightfully sceptical of people asking about 650B conversions where all of these things don’t apply.
Sorry to jump on your post here and rant but I’ve been encountering this opinion a lot lately that 650b is falling out of favor or whatever and I’m just baffled by it. Like 650b was basically extinct until Jan and Grant and Pacenti and VO (and 27.5 mountain bikes) revived it. Now there are a multitude of stock bikes (stock bikes!) in 650b and more aftermarket rim and tire options than ever before. What am I missing? Shit makes me feel old.
I have 650b on my gorilla monsoon I love this size
Me, I’m the one who says it.
I’m also planning on doing a 650B conversion, but from 700C, so this is great to see. Bike looks fantastic and those cantis are super cool!
This looks great, and I bet it rides like a dream. Frame is so sick, and your build Is super rad.
I have done a few similar 650b conversions just like this (and with the same brakes even). You lucked out with the canti posts being positioned as high as they were. I think the 650b is like the mama bear of bike wheel diameters, especially if you are on the shorter size. Nice work!
Long live the towel racks.
Only advice I’d give is just finding small spots where you can throw in some personal flair. I like taping the chainstay in unique ways
You can cold set these old frames from 130 to 135 pretty easily, then get some 26” cliffhangers to fit.
Nice wheels!
Bike would ‘look better’ with three chain rings, smaller rear cogs, and shifters on both sides of the bars.
You can crimp the rear where the tires threaten to rub for a few more millimeters. Vice grips , some pipe and some soft fabric on the outside
Hell yeah!!! Thanks for the shout out!