650c to 26" conversion: someone check my work?

[sandyrs]

I'm thinking of converting my girlfriend's 650c road bike to 26" to get bigger, more comfortable tires into the frame. It has short reach brakes now. I'm trying to figure out what brakes it will need for the conversion- medium reach (47-57mm) or long reach (55-73mm). Given that the rim diameter difference (559 vs 571) is 12mm, it seems to me that it will depend on where the brake pads sit in the slots on the current brakes. If they are at the bottom, then the current reach is around 49mm, so an increase of 12mm will necessitate the use of long reach brakes. If they are higher up the slots, closer to 42mm, then medium reach should work.

I would appreciate someone checking my work on this one!

[palincss]

Does the bike have sufficient clearance at the fork crown and chain stays for 28mm tires? As far as I can see, that's the narrowest 559 road width, and most 650C tires are only 23mm wide.

Regarding brake reach: it's the difference in radius, not diameter, that affects brake reach.

[Ken Robb]

Can you borrow some 26" rims/tires to check fit and clearance?

[sandyrs]

Does the bike have sufficient clearance at the fork crown and chain stays for 28mm tires? As far as I can see, that's the narrowest 559 road width, and most 650C tires are only 23mm wide.

Regarding brake reach: it's the difference in radius, not diameter, that affects brake reach.

This is the sort of stupid mistake I knew I would make! Thank you! So medium reach brakes should work fine for the 6mm of additional reach to the brake track, right?

The frame can clear 650Cx28s with short reach brakes so I'm not worried. It just feels like a waste of clearance to use a wheel size where tires aren't widely available for all the space she has.

[cp43]

This is the sort of stupid mistake I knew I would make! Thank you! So medium reach brakes should work fine for the 6mm of additional reach to the brake track, right?

The frame can clear 650Cx28s with short reach brakes so I'm not worried. It just feels like a waste of clearance to use a wheel size where tires aren't widely available for all the space she has.

You don't mention the position of the pads on the current brakes. If there is 6mm more slot available in them, they might work as is. But, you are correct, going from a short reach (39-49mm) caliper to a mid (47-57mm) will get you the reach you need.

I think the best bet it to do a test fit with a 26" wheel, as suggested above, before you buy anything. It will give you a good idea of brake clearances, as well as tire clearances.

[christian]

Yes, it's 6mm difference.

(571-559)/2.

[christian]

If your GF uses Campagnolo, I have a set of silver Chorus hubs laced into silver 559 rims (Campy Omega maybe - I forget what), in really nice shape.

My wife used them on her much maligned Vanilla, so they have very few miles on them.

If you want them, I'll sell them for half the price of the hubs on the open market (say $150?). Pick up at Thanksgiving if you're in Westchester. (These would also work for running Shimano 11 with Campy 11 cassettes.)

[sandyrs]

If your GF uses Campagnolo, I have a set of silver Chorus hubs laced into silver 559 rims (Campy Omega maybe - I forget what), in really nice shape.

My wife used them on her much maligned Vanilla, so they have very few miles on them.

If you want them, I'll sell them for half the price of the hubs on the open market (say $150?). Pick up at Thanksgiving if you're in Westchester. (These would also work for running Shimano 11 with Campy 11 cassettes.)

Oh man. On this. I was going to put 5800 on the bike and have plenty of campy cassettes. I'll PM.

[palincss]

My wife used them on her much maligned Vanilla, so they have very few miles on them.


What could there possibly be to malign about a Vanilla?

[christian]

Oh man. On this. I was going to put 5800 on the bike and have plenty of campy cassettes. I'll PM.

Ok, so those are sold. Cool beans.

[christian]

What could there possibly be to malign about a Vanilla?It's all in the archives. Basically, it wasn't built well - the brake bridge wasn't at the right height, it wasn't packed carefully and was damaged in shipping, and it didn't ride particularly well. On the plus side, the paint was nice and the resale value was good - about 80% of the new price. My wife vastly preferred her 1983 Trek.