Can I change wheel sizes?
 

I have a Cannondale F5 mountain bike with 26" wheels and disc brakes. I have been searching unsuccessfully for a spare wheelset so I can have slicks on one and knobbies on the other. 27.5" rims are everywhere it seems, so I was wondering if it's feasible to get slicks for that size, and mount them? I don't have a set handy to try, and don't want to buy some just to see, so I figured I'd ask here.

Eric

It's unlikely a 27.5" wheel and tire will fit in a frame designed for 26" wheels as there probably isn't enough frame and fork clearance. Many bikes built for 700c (aka 29") wheels will take 27.5" wheels and vice-versa but not those for 26" wheels.

I should have added, and will edit, the F5 is a MTB frame, not a road bike, so it's not a 700c.

Eric

A 26x2" tire is nominally about 660mm in diameter. A 42mm tire designed for a 27.5" wheel (584mm) is about 668mm in diameter. If your frame has plenty of clearance for a nominal 26x2" tire, then I think you'd be able to fit a 42-584 tire.

Actually, it's not unlikely at all.650B conversions on 26" wheel mountain bikes are often doable as long as disc brakes are involved. I have done one such conversion myself in the last six months.
A few quick measurements, or a test wheel set fitting will soon tell the tale.
In fact, I have done one 26" to 29er conversion. It put the crank higher than I would have liked, but it's what the customer wanted, and the bike had the clearance. Not many have that much though.

26" rims and wheels should be everywhere, but not necessarily high quality with discs.

For 650b, a lot will depend on tire width.

I did a 26" to 700c conversion a while ago. Going from standard 26" to narrow 700c. It worked reasonably well, although the frame dimensions were a bit off.

I know that but many current MTBs are designed to use 700c wheels referred to as 29".

1) where have you been looking?
Many who started riding during the 26” era still have some wheels left. If you’d been local I could have given you a pair.
2) how wide do you want those slicks?
27.5” is also known as 650B, these have the same Bead Seat Diameter, where rim and tire overlap. If you’re OK with a narrower tire, there should be a decent selection of slicks for that size, which would leave the OD about the same.

Dude, it'll work 100% fine and roll better than 26" wheels if we're talking mid-width slicks. People have been using road and cyclocross tires on 700C wheels with 26" disc frames for ages; there's tons of clearance for a 27.5".

Here's an example of a direct swap from 26" MTB to 700C road wheel/tire:
https://www.mtbr.com/threads/is-a-ri...3/post-9683247

https://cimg8.ibsrv.net/gimg/bikefor...5d3eed97dc.png

Wow, thanks! I had not even considered 700c, I'm definitely looking for mid-width or narrower slicks since they'll be for rail trail and casual street riding around town, leaving the knobbies for when I need more aggressive tires.

Eric

Not looking for wide, and yes 26" wheels can be found, or cheap enough donor bikes but none I can find with disc brakes.

They aren't that hard to find. Here is a whole page of them https://www.universalcycles.com/shop...?category=5479 If you were near me, I'd give you a pair, since I have several pairs that I'm no longer using.

One area that could be a problem is if your current wheels use quick releases rather than thru axles. Some thru axle wheels can be converted to quick release but many others can not so that is another consideration

I've converted old 26" mountain bikes with 700c and 650b wheelsets. 700x23 roadie tires fit fine and so do 650bx47 tires with knobbier tires. Do it.

There are still many 26" rims of good quality available, many good quality hubs available, and good quality spokes available. I know it is not the most common way to get good wheels, but building or having your own built is still an option.