Cycling UK Forum

Hi,
Recently I had a failure of the straddle attachment on my front brake. Fortunately this happened just after washing the bike, I reclipped the brake together, squeezed the front lever as a check and bang! The consequences of this happening out on the road are just too scarey to think about.

The brakes are just over 3 years from purchase date. Only used on an old Alan CX frame that I fitted out to a fixed gear road bike, this bike is not my only bike and so doesn't get used all the time. The bike is not used with any loads, just a rider of about 70kg.

The metal fitting on the straddle has just broken clean across in what appears to be a brittle failure.

Really I want to warn others of this potentially nasty failure and if you use something similar to check them throughly.







I have notified the mail order supplier I got the brakes from, awaiting a reply. They rejected my sensible product review where I warned others to check their brakes, quite shocking that.

I like the brakes and they are ideal for the bike, now I need to find an alternative straddle arrangement. The brakes came with a choice of different length straddles and so I have reluctantly fitted one of the unused spares for now.

If you use Avid Shorty brakes or anything similar with the same type of fitting please check the straddle.

blimey. From your photos it is clear that the cable has been fitted correctly and there doesn't look to be very much corrosion. It is also clear that the cross-section of metal withstanding the load (under the sticker!) isn't very much; it looks like a dead cheap (read weak, brittle) die casting to me and in that cross-section I would not expect it to be immune from breakage even if the casting itself is sound.

I have similar Avid brakes (but the older version that has a simple arm, not a 'triangular' one) and I must say I didn't fancy the straddle link wire either; it didn't seem to match the quality of the rest of the brake.

For a solution, you could try the equivalent shimano parts. These exist in four generations;

1) BR-M100 / BR-M501 etc link wires; the knuckle (which I can't find for sale any more) has a pinch bolt in it and there is no 'outer sleeve'. The link wire itself can be bought separately http://www.sjscycles.co.uk/shimano-br-m100-link-wire-c-16-x-106mm-82y-1701-prod30189/, http://www.sjscycles.co.uk/shimano-br-m501-link-wire-b-16-x-82mm-82y-1720-prod30188/

2) Shimano 'M-system' link wires. Similar design to Avid but a stronger knuckle and a better cable swivel. Available in different lengths, letter coded A---F (maybe others; a Sheldon Brown page lists them IIRC) eg type A here;

http://www.chainreactioncycles.com/shimano-cantilever-link-wire/rp-prod34706

I have never seen one of these link wires fail in normal service; however like all link wires with an 'outer' the most flexed region of the main cable (near the pinch bolt on one brake arm) is hidden, and the main brake cable can fail at this point. This is a very nasty failure mode; unless you lift the 'outer' and inspect from time to time, you would not see the cable starting to fail.

3) Shimano 'unit link' straddle for CX-50 and CX-70 brakes eg
http://www.sjscycles.co.uk/shimano-cyclocross-br-cx70-unit-link-8k4-9802-prod30074/

4) Shimano unit link for BR-M550 (nice design, but expensive!) eg

http://www.sjscycles.co.uk/shimano-br-r550-link-wire-e-for-cantilever-brakes-8a2-9808-prod30087/
http://www.sjscycles.co.uk/shimano-br-r550-link-wire-f-for-cantilever-brakes-8a2-9809-prod30088/

Now the whole reason for these 'unit link' wires is that, on a bike without mudguards, there is no type of cable failure that is likely to jam the wheel. By contrast if you have a 'traditional' straddle and yoke arrangement, and the main cable fails, the straddle can drop down onto the (knobbly) tyre and cause an instant jam. Now obviously if you use mudguards at all times, or have any kind of bracket under the straddle (eg a lamp bracket) this kind of failure should be of no concern to you whatsoever; it just can't happen.

So a very good solution (if you have brackets and/or mudguards) is to use a 'traditional' straddle and yoke arrangement. If any part of the cable starts to fray you can see it easily and it is more adjustable, too.

cheers

Thank you Brucey for such a comprehensive reply and all the links to better straddle designs. That's very helpful indeed.

I agree about hidden portions always masking potential fraying. I liked the arrangement as it did keep the brakes nicely centred all the time. But relying on such a poor casting lets everything down.

Going forwards I think I will change things over to a traditional straddle and yoke, this bike is always run with mudguards. Should have some yokes kicking around from some old cantilever brakes if I can find them.

Thanks.

Hi folks,

Thanks both for helpful posts.
I've used Avid Shortys in the past and have these straddle wires in the parts box - well, not anymore.

Best wishes,

Luke

A little update on this.

I purchased the front and rear brakes from Chain Reaction Cycles, 3 years ago.

I have just received a refund for one pair (£17), this is appreciated as they didn't have to do this, so good service from them.

My real concern was someone suffering a failure while out on the road rather than obtaining a refund. But apparently any claims get sent to the supplier so they will be made aware of the failure and hopefully investigate.

Any kind of brake can suffer a failure, that's why we are obliged to have two independent braking systems.

Yes, failure on the road could be very bad, but you have another brake, the failure mode Brucey mentioned above is (probably) worse (locked front wheel)

Quite agree with you on this.

Also why even on this fixed gear bike I still feel happier running a rear brake. Once my legs start spinning out I find I lose the ability to slow down on the fixed and use the rear brake too.

Still I can think of many places where a front brake failure would mean I would not stop in time at a junction or run into something ahead.

When the MTB first arrived on the scene with big knobbly tires - if you snapped a brake cable the cantilever strop would drop and catch in the knobblies on the tire - ouch!

Des49 wrote:Quite agree with you on this.

Also why even on this fixed gear bike I still feel happier running a rear brake. Once my legs start spinning out I find I lose the ability to slow down on the fixed and use the rear brake too.

Still I can think of many places where a front brake failure would mean I would not stop in time at a junction or run into something ahead.

Absolutely - but so can wet leaves...
Yes, I've had that happen, fortunately I was quick enough to stop all braking and accelerate through the junction before the cars coming the other way got there (close though)