specialised tricross

[Drew Stevenson]

I have just bought a spesh tricross and find that under front wheel braking there is severe judder can anyone tell me how to stop this ,is it a problem that you live with, the bike is due a service soon so will also mention it to them but if any body can tell me what is causing it in the 1st place at least I can pass that on to Dales Cycles any info much appreciated.

 

[MrJamie]

I was looking into cyclo-cross bikes and read that its quite a common thing with cantilever brakes (so i guess you dont have the disc version?).

From memory its something like.. when you brake the fork flexes backwards which is normal, but on canti brakes the flex tightens the brake cable and makes the bike brake harder and harder, until it slips which unflexes the fork then the pads bite again, bend the fork, but much faster so its like an on/off thing.

I recall it being common enough that it happens a lot on a lot of different cyclocross bikes because of the canti brakes and will probably be allover a google search. Im not sure that there was a good solution, but if youre clever with levers and angles i think you can reduce it by doing something with the brake cables so that the flex induced tightening has less of an effect on the brakes, maybe by lengthening the horizontal cable. Check google though (or other replies here), im not talking from first hand experience, just from reading about cyclocross bikes.

 

[Drew Stevenson]

I was looking into cyclo-cross bikes and read that its quite a common thing with cantilever brakes (so i guess you dont have the disc version?).

From memory its something like.. when you brake the fork flexes backwards which is normal, but on canti brakes the flex tightens the brake cable and makes the bike brake harder and harder, until it slips which unflexes the fork then the pads bite again, bend the fork, but much faster so its like an on/off thing.

I recall it being common enough that it happens a lot on a lot of different cyclocross bikes because of the canti brakes and will probably be allover a google search. Im not sure that there was a good solution, but if youre clever with levers and angles i think you can reduce it by doing something with the brake cables so that the flex induced tightening has less of an effect on the brakes, maybe by lengthening the horizontal cable. Check google though (or other replies here), im not talking from first hand experience, just from reading about cyclocross bikes.

Thanks for the reply Mr Jamie the brake set up is as it was since bought the problem occurs if I brake quickly ,if I feather the brake it is usually ok will pass on prob to bike shop , thanks again for the reply

 

[Hawk]

Thanks for the reply Mr Jamie the brake set up is as it was since bought the problem occurs if I brake quickly ,if I feather the brake it is usually ok will pass on prob to bike shop , thanks again for the reply

Spec customer service is excellent. Dales (at least the Glasgow branch) know exactly what it is and will fix it for you for free, under warranty.

There is some debate over what causes it. It's quite a complex effect no doubt. One claim is that the length of the brake cable between where it is suspended by the hanger and where it splits in to two is JUST the right length such that its resonant frequency (where it vibrates most easily) is the same as that of the forks: the forks start vibrating under braking, the brake cable follows and because of the vibration of the brake cable there is a constant change in the braking force applied which causes the "judder". I found, by experimentation that there did appear to be some brake-cable vibration effects in play - pulling the brake cable, between the fork and stem where it is freely suspended, with my hand meant I could decelerate more rapidly without getting judder.

A similar theory is that when you first start braking, the forks bend backwards slightly, moving the brakes further away from the hanger. As a result, there is an increase in braking force. The forks bend more and this process continues until the forks are so bent that you get a minute front wheel "skid" back to the fork's starting position, and then the same thing happens again. I'm not convinced about that one.

IN ANY CASE:

The solution is to change the way the brake cable hangs. The brake system is modified such that the brake cable is hung from between the forks upwards. This attachment is also quite flexible which I suspect has more to do with the reduction in juddering than anything else.

It is totally effective in eliminating any detectable judder

 

[ianrauk]

It's a well documented problem with the Tricross.
You need a fork hanger like this

From Hargroves Cycles. £10.00
It will eliminate the judder.

 

[wakou]

http://www.jejamescycles.co.uk/tricross-fork-brake-hanger-id57553.html#info

Ian beat me to it..

 

[Drew Stevenson]

thanks for the information I will pass on the information to Dales glasgow and hope to get the problem fixed

 

[Hawk]

thanks for the information I will pass on the information to Dales glasgow and hope to get the problem fixed

It's OK, Dales are a Specialized Dealer and know exactly what to do to fix the problem. Just tell them you've got brake judder on the front of your tricross, tell them you're under warranty and ask if they can fit a fork-mounted hanger; they know what they're doing (mostly)

 

[Drew Stevenson]

Mr Paul the bike is new , I knew there was a recall on the previous model but this was supposed to have been resolved , thanks for the reply at least I know the problem can be fixed

 

[Drew Stevenson]

It's OK, Dales are a Specialized Dealer and know exactly what to do to fix the problem. Just tell them you've got brake judder on the front of your tricross, tell them you're under warranty and ask if they can fit a fork-mounted hanger; they know what they're doing (mostly)

thanks hawk don`t know why the hanger was not fitted proir to leaving shop

 

[Drew Stevenson]

Thanks for all the replies much appreciated