Carbon fork judder/vibration

[Paul Smith SRCC]

On the toe-overlap issue, I did notice that the CTC magazine headline review (June July 2008) on road and audax bikes made an issue of it. Dan Joyce certainly seems to agree with me, especially after he fell off the Pearson Audax Pro, and he was lucky enough to have room to squeeze a mudguard on.

Toe overlap is often something that divides opinion, it can indeed catch riders unaware especially when they have been riding a bike without overlap and then change to riding one with.

Many, my self included, have always ridden bikes with overlap with no problem, for sure it is something you need to be aware of though and the riding style needs to take overlap into consideration, applies especially when turning the bars at slow speed through traffic for example. However for a time my commute was 18 miles each way South to North through suburban London on a fixed, even then I personally had no issues as far as I was concerned with toe overlap.

Paul_Smith
www.bikeplus.co.uk

[james_h]

Is this judder still a problem with the 2008 model? I'm thinking about getting a tricross, but not if I'm going to have this problem!

Thanks, James.

[Chris Clode]

On the Specialized web-site I can't spot any difference with the 2008 model. I'm not sure when Specialized update their bikes, but mine was bought (complete with judder) in September 2007. The spec on the web site state "Avid Shorty 4, cantilever brake" under features, but "Tricross-specific forged linear pull, road-lever specific length" under Technical Specifications. It was the Avid Shorty 4 brakes that caused the judder on mine, so I'd avoid them if they still have them fitted, or at least get the dealer to agree to change them for you, provided you are happy to have V brakes instead.

[james_h]

I spoke to a shop earlier that said Specialized had replaced the brakes on new bikes since xmas time.

[james_h]

What's the idea with cantilever brakes anyway (over V brakes) ?

[Chris Clode]

Do you know what brakes are being shipped with te Tricros Comp now?

I'm not sure of the reason for fitting cantilever brakes, but do cyclo cross bikes tend to have them because they can be set up so that the pads are further from the rims to allow for more mud clearance than V brakes?

I've also read that the cantilever brakes have more modulation over V's, which contradicts what I thought Specialized told me. I thought the reason to swap to V's was to get more modulation and therfore reduce the snatchiness which was causing the fork judder.

One thing I'm confused by is that I thought that V brakes could only be used on flat bars. My Tricross is now fitted with its replacement Tektro V's and they appear to work OK, if very, very, very sharply.[/quote]

[madammemarie]

Is this judder still a problem with the 2008 model? I'm thinking about getting a tricross, but not if I'm going to have this problem!

Thanks, James.

Yes, it's still a problem and i'm shocked that Specialized hasn't addressed it properly. I bought the Tricross Sport almost a year ago and after struggling with the brakes, I only find out it's a known problem now!!! Result? Front brakes are V braks, back brakes are cantilevels. I still have to test them (only picked up bike today), but I will get in touch with specialized about those mini-v brakes and sort it out for good, hopefully. My local bike shop, though very good mechanics, they are a bit stubborn....

It's a shame because, this problem aside, it's a top bike, at least for me. I wanted a light, fast tourer/commuter and i got that.

If you buy the bike now, you are likely to have the mini-v-brakes for free from Specialized. If you are willing to make that little change, then go for the Tricross.

By the way, I saw a Tricross single speed (the green one) at Evans in Canary Wharf with V brakes! But the shop assistant didn't know anything. Doesn't surprise me.

[ade]

I picked my Tricross up just before Christmas 2007 and I was surprised it came with mini v brakes - it must have been one of the first. The v brakes work fine as long as your wheels are true and you can keep them running fairly close to the rim. As I use the bike on a variety of surfaces the wheels now need truing up again and the knock on is that the v brakes need to run quite wide of the rim and this means that the STI lever has to pull much more cable to get the bike to stop.
The other downside with the v brakes is that there is no cable adjustment so to get your wheel off you have to deflate the tyre (or if you have wide tyres like me) unbolt the cable. Less than ideal. I fitted some in line barrel adjusters to overcome that.
I did raise it with Specialized

[Thank you for your email it is always good to get feedback from riders.

The Tektro mini V-brakes are now fitted to all the bikes in the Tricross range. This was to address an issue we were having with fork judder.

I sympathize with your problem. I run my brake pads very close to the rims on my bikes as I like the brake to bite early on in the lever travel. As you found this means it is sometimes hard to disengage the brakes when you need to remove the wheel. I've found the easiest way is to always carry a mini pump, let the tyre down slightly to clear the pads. Alternatively, if a pump is too bulky, carry a 5mm allen key to release the cable when removing the wheel.

The Tiagra levers and mini V-brakes should work fine together. If you are having problems with power or modulation, a simple trick is to put some "toe in" on the pads. This is where the front of the pad is angled towards the rim slightly on both sides of each wheel. "Toeing in" the pads correctly improves the feel of the brakes enormously.]

I believe that you can fit a device called a Travel Agent which means you can slacken the cable and it increases the amount of cable the lever can pull. They cost about £18 each.

So, the upside to this is that my bike doesn't suffer from fork judder but Specialized 'solution' is less than ideal to correct what is a design flaw. Come on Specialized fix the problem properly. The logical step is to put disc brakes on them

Overall I'm happy with the bike. If you want a solid multi-use bike for all year riding it is fine albeit the tyre / toe clearance can be an issue when mud guards are fitted and you'll need to spend money to get the brakes set-up and working sensibly.

[MartinC]

Brake judder with canti brakes may be due to the type of cable hanger used. If the hanger's effectively attached to the head tube (e.g. in the stack of spacers) then when the fork flexes the tension on the brake cable will vary 'cos the brake is moving relative to the hanger. This seems to me like a prime opportunity for brake judder. You can get cable hangers that attach to the fork crown and I've heard people say that this cures the problem.

V Brakes will also cure the problem for the same reason - no variation in cable tension.

Mini V brakes can be a problem with road brake levers. They don't need as much cable pull as full size V brakes but sometimes enough to cause the adjustment to be crucial and out of true wheels or worn pads may be a problem.

In my experience the cable pull/pad travel equation for V brakes depends heavily on the height of the rims above the brake bosses. You can work out the geometry - but the bigger the distance then the more pad travel you get. I'm running some Campag mini V's on a Trek 520 with STI levers and they work fine - the levers pull enough cable to not worry about wheel truing or pad wear.

You definitely need in-line adjusters or adjusters on the noodles - your only quick release is too slacken off the cable enough to unhook at the noodle.