Wheel/Fork Width

[Andy in Germany]

Or: 'Learning by doing' comes back to bite me...

So I've ordered a new wheel from Taylor Wheels, and it turns out it is narrower than the old one (Old= ca.25-26mm, new = ca23mm) and my V-brakes don't work.

This was my own silly fault for not checking twice.

However, on refitting the old wheel I remembered that this one is slightly borderline, and I'd made a "temporary" fix by putting washers between the blocks and first thick washer. Of course I then forgot all about this.

The original bike frame is fairly old and had Canti brakes; I've come across a problem before that old MTB frames with early pattern canti brakes were a bit wider and V-brakes don't always work on them. Is this also the case with some later Canti's?

I'm currently deciding what to do about this; there don't seem to be any wider rimmed wheels available. I have considered replacing the forks with more modern ones, also because that would give me extra points to fit lowriders on the front, but is there another possibility I'm missing?

 

[fossyant]

Just adjust the pads, that's all you need to do. I'm running a 30 plus year old MTB with Canti's and I've some Ryde rims and some no-name Decathlon wheels - both are fairly narrow rims. Even my CX is running canti's with narrow road rims.

Pics might help.

 

[Andy in Germany]

Just adjust the pads, that's all you need to do. I'm running a 30 plus year old MTB with Canti's and I've some Ryde rims and some no-name Decathlon wheels - both are fairly narrow rims. Even my CX is running canti's with narrow road rims.

Pics might help.

Unfortunately that won't work. It's not clear from the post but I'm using V brakes, not Canti's.

On the new wheel the V brake pads barely make contact with the wheel rim before the top of the arm hits the mudguard, even with an extra washer between pads and the thick V-brake washer. The old rim is about 4-5mm wider than the new one and I can't make that difference up with washers without making the screw thread very short indeed. I've looked around and I can't find a supply of wider rims.

 

[FishFright]

Unfortunately that won't work. It's not clear from the post but I'm using V brakes, not Canti's.

On the new wheel the V brake pads barely make contact with the wheel rim before the top of the arm hits the mudguard, even with an extra washer between pads and the thick V-brake washer. The old rim is about 4-5mm wider than the new one and I can't make that difference up with washers without making the screw thread very short indeed. I've looked around and I can't find a supply of wider rims.

Move the pads further up , or down , I forget which .

V brakes should be very adaptable to various rim width . I've run the same v brakes, on the same bike, with narrow xc rims and wider DH spec rims . Using fresh blocks of course.

 

[Andy in Germany]

I just took the wheel and brakes off the bike to measure the distance between the brake bosses, having measured several forks in the workshop for reference. The workshop forks bosses are 72-74mm apart. My forks are 83mm, which I think shows where the problem lies.

I'm guessing this is because of the age of the frame, and because it is built for Canti brakes, which as @fossyant says are more forgiving of this sort of thing. Ironically on the rear triangle I had the opposite problem and had to bend it to fit an 8 spd cassette hub.

I'll have a look through the available forks to see if one fits, otherwise I'll order a new set.

 

[T4tomo]

You might also be exacerbating the problem by using V brakes with Canti levers, which is a bodge that sometimes works, but suboptimal.

 

[Andy in Germany]

You might also be exacerbating the problem by using V brakes with Canti levers, which is a bodge that sometimes works, but suboptimal.

Fair comment, but I know they're V-brake levers; took me weeks to find them.

 

[si_c]

A lot of the v-brake sets I've seen have multiple spacers and washers on them. Normally you'd have a spacer on the inside (with the concave face for adjustment) and a second spacer on the outside of the arm. Have you tried moving the outside spacer inside the arm?

Edit to add a picture:

 

[Andy in Germany]

A lot of the v-brake sets I've seen have multiple spacers and washers on them. Normally you'd have a spacer on the inside (with the concave face for adjustment) and a second spacer on the outside of the arm. Have you tried moving the outside spacer inside the arm?

Edit to add a picture:
View attachment 722119

At work, we always put the thicker spacer on the inside. With my current wheel I've already added an extra washer between the block and the thick washer to get some grip, but even with that it isn't enough.

 

[Andy in Germany]

To summarise the "learning experience" so far:

Wheel Rim Width:

Old rim: 25-26mm
New rim: ca23mm

Distance between brake bosses

Current forks: 83mm
Others: 72-74mm

Distance from boss to rim each side with current fork:
Old rim: ca 28mm
New Rim: ca 30mm

I already use extra spacers to extend the reach of the brakes. I can't put that many spacers on and still trust the screw to hold it together.

Distance from boss to rim on each side using 'new' fork and new rim: 24mm.

Next step will be to take the forks out and make sure they're 1" and not 1 1/4".

 

[Ian H]

You might be able to find chunkier blocks. Have a look at Kool-stop 'City', for instance. They might do the job.