Fred Smith

I'm thinking about replacing the rims and wheels on my commuter MTB (right now it has standard 26 inch MTB wheels with slick tires) with 650c rims and road tires. Essentially, I'd like a much narrower rim / tire combo to speed things up (and maybe a little project to occupy my spare time too).

Apart from needing shorter spokes and potentially having to adjust the breaks so they line up with the 1/2 inch less diameter rim, does anyone see anything fundamentally wrong with this idea?

The other alternative would be finding 26 inch rims with a 19.6 mm width - but I haven't seen any.

Thanks!

badamsjr

Fred: I am actually thinking of going the OTHER way. Puting 26" wheels/tires on my 650c bike. The 650c tires I have found are only 23's, and I would like something a little wider--say 25 (1"), or 28 (! 1/8"). Since the 650c is an ISO 571, and 26" are ISO 559, I would need to put 'long-reach' brakes on it.

BTW I have Velomax Rogue 26" wheels, and they are 19 or 20mm. I have run 1" tires on them with no problem. My advice would be to do a little more research on wheel availability, and see what tires are out there. I like Conti Ultra Gatorskin 1 1/8".

HillRider

You have it backwards. 26" MTB wheels are ISO 559 and 650c rims are ISO 571. therefore, the 650c wheels will be 6mm larger in radius than your current MTB wheels. So you will need longer spokes and the brake pads will have to move 6 mm higher to align properly

Gonzo Bob

I don't think you'll see much speed difference in going to 650x23C, even if you now have a 26x2.0 slick on there. I've run a couple different tire widths on my MTB and I don't see a perceptible speed difference between 26x1.4 slick and 26x1.0 slick. I run 26x1.4 most of the time on the commuter wheels because I can run them at lower pressure for more comfort. Many current MTB rims are narrow enough to accept a 26x1.0 so try that if you haven't already.

Fred Smith

Thanks for the correction! And thanks everyone for the input. I'm going to scout out some 1 inch slicks (I have 1.5 on there now).

Jeff Wills

I have a couple rather old (15 years?) Matrix Aero rims in the MTB size- they're about 20 mm width. They're 36-hole, so they'll make a real oddball set of wheels once I find the right project for them.

BCRider

Fred, check out Panaracer Pasela 26x1.25's as well. The set I had fitted onto the fairly narrow style mountain rims I had at the time and formed a decidedly egg shaped cross section. The tread was more consistent with the curvature of a 23 or 25mm road tire while the width came out to 1.125 and the height was the only part that was about right at around 1.25. They rode like the wind and the kevlar TG belting really did eliminate flats for me for the 4 or so years that I was riding those tires.

tcs

Understand that you can change the geometry of the bike with wheel/tire swaps.

Lets approximate and say that a tire is about as tall as it is wide.

So 559 + 38 + 38 = 635mm diameter (what you're riding now)

571 + 23 + 23 = 617mm diameter (what you're proposing)

So the bike should sit ~ 3/8" lower. But of course the typical MTB was originally designed for 2.125" wide tires.

559 + 54 + 54 = 667mm diameter

So perhaps the bike is sitting ~ 1" lower than originally, and the trail will be altered as well.

This may or may not be a problem, depending.

tcs

dabac

I'm thinking "not worth it". Brake hassle + money + effort for a few mm narrower tires - which won't make much of a difference on the road. Maybe if you stumble across a ready-built set of 650s, at a ridiculous price and you think you've got the required brake adjustability to pull it off.
I've used some 1.0 and 1.2 slicks on my rims(which are nothing special in terms of width) and it works just fine as such.
I'm about to replace them with something a tad wider though, to get a bit more insurance when going over curbs. Bunnyhopping a bike with panniers just isn't an option.
And if your bike came stock with wider-than-average rims, then looking for a fairly lightweight XC set of MTB wheels is likely to get you fairly close to what you want in one go.

fietsbob

& fwiw ... 700c seems a conversion some have used, But.. Only on a disc brake bike, because the rims are far apart in radius , so only a hub brake will line up.

OTOH, Schwalbe 'big apples' are said to roll very nicely , a 559-50 tire, a change of only the tire ..

I've got Schwalbe's Marathon Plus in a 1.75 width after having Continental's 'travel contact' on there before .

the TC was still fine, people looked at it and thought I had worn the center band down to slick. when instead it came that way, smooth and easy rolling , design has a flanking row of knobs, but they dont contact the ground on pavement.

LarDasse74

6 mm of brake adjustment is actually pretty big. Converting old road bikes from 27" to 700C requires a 4mm change ant it often requires brake modification or complete change.

Sounds like you have decided to go with narrower tires on the 26" rims. This is a good idea, I think... because of the aforementioned brake-pad issue, and because, on V brakes or canti brakes, going to a larger rim will decrease braking performance considerably.

For higher speed get higher pressure tires (1" @ around 100 - 125 psi should be fine as 25mm tires are as narrow as anyone really needs). Also consider changing the cassette or chainrings to get faster gear ratios. I always found that a mtb with slicks was super easy to spin out in the fastest gear.

dabac

There's a brake adapter available, think Mavic makes one. Looks like an old-style brake booster, bolts right on and moves the brake bosses to the proper position for the 700C rim.