peripatetic

Since I don't have any myself, I don't want to go buying some if this won't work. I've scrounged around here and the Internet, and can't find if anyone has done this, so it makes me wonder if I should even try. And quick don't-worry--I don't plan on doing this with any high-end vintage frame, probably something fairly low-end, maybe my girlfriend's old 70s Motobecane that's due for a tuneup and upgrade anyway.

I've been reading up on it, but I can't quite figure out if the wheels with, say city/slick tires would fit into an older road frame. My eventual plan would be to make a cushy-riding singlespeed for cruising around town. Sort of a poor-man's 650b conversion. But I'm figuring I'll need to drop the brake shoes 11.5mm in order to hit the new rims. Is that correct? Would I even be able to find brakes with that much distance? (I know Rivendell sells long-reach brakes, but I'm kind of hoping some old centerpulls will do it). I figure I can find some decent, cheap MTB wheels used from someone locally, and I don't have the cash right now to buy 650bs.

Any input, factors I haven't considered?

rhm

Fitting brakes will be problematic. Smaller wheels means longer brakes, possibly so long that it's not an option. You might be better off with a MTB frame, since it's built for that wheel size, or a cruiser type bike built for 26" wheels.

By an odd coincidence yesterday I rescued a bike from the trash, which is a Free Spirit from the late 70's or so. It has a lugged frame, 10 speed gearing, cotterless crank, and takes 26" wheels. 26" as in MTB wheels, that is, not the larger three-speed size wheels. PM me if you want it.

sailorbenjamin

Some kids bikes have really long brake calipers. If you're going single speed, you could use an old coaster brake cruiser wheel.

Zaphod Beeblebrox 

I'm working on a 26" conversion using a Schwinn Varsity. standard 126mm rear hub and 100mm front hub spacing.

There's no brake caliper with long enough arms to reach, and if it did the arms would be so long they'd be like noodles. I considered a coaster brake, but I really wanted at least a 5 speed cassette. My solution was to go with drum brake hubs in the front and rear. I got a Shimano 7 speed rear hub with a Drum brake, and a Sturmey Archer Dyno&Drum Brake hub in the front. They're laced to 26" Sun Rhyno rims which are going to wear big fatty 2.125" balloon whitewall tires.

The drum brake hubs are cool.... i got the rear for 30 on ebay but dropped 60 on the front dyno hub...you could get a front drum brake hub without the dyno for 45 new.

Kommisar89

Trail. Using significantly shorter wheels will reduce the trail which might result in twitchy or unsafe handling. Or it might not. Probably depends on how much trail the bike had in the first place. Somebody who recently did an actual 650B conversion posted about it on the forums and was not happy with the results for that reason. YMMV.

yepyep

+1 on the coaster brake

sciencemonster

I did this no problem with my wife's '75 or so Raleigh Competition. I got new Diacomp centerpull brakes and they reached no problem. The wheels came off her Sports.

The bike looked pretty cute with the undersized wheels.

The brakes looked just like the old school brakes that came with the bike, except they were shiny.

This would be 26 x1 3/8 EA3 wheels off a Raleigh 3 speed, and these brakes:

https://www.universalcycles.com/shopp...33&category=34

yepyep

Also, depending on the frame, bottom bracket clearance could become a real issue. Pedal Strike!

wrobertdavis

26" MTB and 650B are not the same. A 650B is taller. I did the math for putting 26" wheels on an 80's Japanese road bike frame. The centerpull brakes recommended by Rivendell site would *barely be long enough. However, the crank would be lowered so much it was a no-go. By the way, this would have been an easy 650B conversion but MTB wheels are no-go. I just put a late 80's mountain bike into road service and I am very happy with the results. The biggest piece of work was converting from straight mountain handlebars to drop road bars. Everything had to be changed out (stem, handlebars, brake levers, brake cable hanger, shifters).

Bob

unworthy1

also the EA-3 is 590mm and a 26" Mtn. bike rim is 559mm: big difference, even tho they are both called "26-inch".
650B is very close to the EA-3 at 584mm

peripatetic

Okay, thanks to everyone for the input. I think if I were to do this, I'd use one of Sheldon Brown's solutions. Kommisar, what do you mean by "trail?" Are you talking about wheelbase? If so, I'm not as worried with an older frame; however, I will make sure to monitor geometry before attempting such a build--both bottom bracket height and top tube length. Anyway, for now, I was just trying to figure out if it would even be feasible before considering actually doing this.

rhm

I'm all for hub brakes-- there are disk brakes, drum brakes, band brakes, roller brakes... all lever operated. But I don't like coaster brakes.

Kommisar89

Trail is the distance between the contact patch of the tire on the ground and a theoretical point on the ground ahead of that determined by drawing a line along the steering axis (imagine a line going straight down your steering tube) to the ground. The greater that distance, the more your front wheel will resist turning. Conversely, the shorter that distance the less resistance and if there is to little resistance you get twitchyness. A track bike or crit bike might be intentionally designed with shorter trail for quicker steering response while a touring bike would have longer trail to provide stability. With Short trail, every small bump, rock, or groove in the road can send you off in a different direction requiring a steering correction. In extreme cases this can be dangerous. A smaller diameter wheel will effectively shorten the trail. Whether this causes a problem or not will probably depend on the bike's original geometry, how much trail it had to start with, and how sensitive you are to the effects of that.

If we had all of the measurements we could determine exactly how much trail would be reduced but even then we could only speculate about what the practical effect of that might be. Really all I can say is try it and see what happens.

noglider 

Why would you want to do this in the first place?

sciencemonster

I did it to shorten the bike so my wife could get on a men's frame comfortably. It was the smallest size made, and once she got used to the top tube and drop bars, I changed her over to tubulars and a rear derailler. It was a transition, but it worked great.