Cycling UK Forum

Hi all,

I went down to the LBS yesterday and they casually mentioned that I should do something about a problem they could foresee with my rear brake.

A picture is worth a thousand words:





It seems that I need a rack with arms that take an excursion around the canti cable at that point to allow the yoke (am I saying this right) to travel upwards without scraping.

Can anyone recommend a solution? I assume I need a new rack, but perhaps this is misguided?

Thanks

Vlad

If you swop them over left to right and right to left the twist should be out of the way of the straddle wire.
I they're still too close bend them into an arc so they clear it.

reohn2 wrote:If you swop them over left to right and right to left the twist should be out of the way of the straddle wire.
I they're still too close bend them into an arc so they clear it.

I tried the swap - to no avail. They look twisted, and obiously they are but they are symmetrical and completely interchangeable with no effect in resultant spacing.

The bending - to be honest I'm not a fan of doing that.

If there is a new rack to be had, it's not a problem, I need a new rack for another bike, so I could transfer the existing one to it and have a new one for the Pompino.

Thanks
Vlad

.

There is a type of seat lug clamp intended for fitting a four-point rack to a frame without mounting points and which has built-in mounting points. That might be a way of mounting the arms of your rack higher.

eg:-

http://www.winstanleysbikes.co.uk/produ ... Seat_Clamp

PS I can't see how another rack would make much difference: it looks at though the problem is the position of the mounting bosses in relation to the brake, especially as they are on a wishbone arrangement rather than (wider) seat stays. Your rack-based choices seem to be bending the arms, which you have rejected or mounting them differently: higher up being the most obvious workable option. No matter which 4-point rack you fit, the arms will be going to the same bosses. A higher/wider rack might change things a bit but not enough, I suspect.

Vladimir wrote:

reohn2 wrote:If you swop them over left to right and right to left the twist should be out of the way of the straddle wire.
I they're still too close bend them into an arc so they clear it.

I tried the swap - to no avail. They look twisted, and obiously they are but they are symmetrical and completely interchangeable with no effect in resultant spacing....

I agree with R2, swapping them will definitely improve matters appreciably.

If you buy longer bolts and spacers that will also help.

Bending the rack stays is perfectly normal and nothing to get excited about BTW.

cheers

Rack stays are mostly meant to be bent to help obviate (not sure what that means) exactly such problems as these. Only don't bend them when they are fixed on your bike as this can damage the fixing points good and proper.

ideas

a) space out mounts on seat stay using longer bolts - i often use the locking nuts from presta valves for this purpose.

c) a tourtec rack which uses struts with a a bend in them.

d) canti brakes with a different geometry such that straddle wires go above the struts.

e) mini v brakes.

f) v brakes but you might need to use a travel adaptor to match to levers.

g) existing cant brakes but with different straddle wire set up so wire goes above struts - but check that performance is satisfactory.

tim_f wrote:
g) existing canti brakes but with different straddle wire set up so wire goes above struts - but check that performance is satisfactory.

The brakes look like Tektro 520s or 720s. If the arms are set horizontal (as they usually are, and in this case appear to be) then the brake MA is not sensitive in any way to straddle wire geometry.

cheers

I literally came on here to say "what if I get some long bolts and a load of washers and fit them between the rack arm and the frame"

Seems like it might be the cheapest option!

Alternatively there's this: http://www.evanscycles.com/products/tor ... k-ec006628 £45 for the rack. About £12 more than my usual Topeak ones.

Mini Vs might be a solution as well, and in fact I always thought I'd change the brakes from the word go, but now that I've ridden with the cantis on, I seem to get on with them just fine.

Regarding the position of the yoke with the brakes engaged, I should have taken a picture of this. The pictures are taken with the brake not engaged. You can see in the pictures that there is some paint already missing from the yoke from the braking I've already done on the bike.

I need to sort out the solution before the pads wear anymore, so I'll be trying the long bolts and nuts on monday sometime.

Just bend the stays. It works.

how was that done? using a vice or something similar?

I just have no idea how I'd go about it!

Vladimir wrote:I tried the swap - to no avail. They look twisted, and obiously they are but they are symmetrical and completely interchangeable with no effect in resultant spacing.

?

The bending - to be honest I'm not a fan of doing that.

?

If there is a new rack to be had, it's not a problem, I need a new rack for another bike, so I could transfer the existing one to it and have a new one for the Pompino.

Thanks
Vlad

You seem like someone who's made their mind

Not really; it's literally a case of me needing a new rack for the carlton corsa. That rack which was on there since the 70s needs to be replaced.

Hi,
Your stays are strip stainless steel, just use your hands and bend around a broom handle, that way there will be no sharp ridge to probagate cracks.
They bend easy, but do it slowly a bit at a time and just offer the bracket up to the frame and rack till it will fit and clear the brake mech.
From your pics just swapping bracket L to R would do it for sure.
Thats exactely what we all do to get the brackets to fit, if the ends of bracket with holes will not lay flat on frame mounting bosses or rack, just use the jaws of an adjustable spanner to grip a portion of bracket and bend with thumbs for a neat bend, this will not weaken the bracket enough to be a problem at all, just dont bend it in the same place back and forth, that will make it weak.