Sticking BB7 on a hardtail

[jherich]

My BB7's are driving me nuts, I've tried brand new Jagwire cables, and now new Odyssey Linear cables, but my brakes continue to stick. One of the lines is a staight run to the rear brake using hydrolic style mounts, and the other runs through the star nut down to the fork. I started out using a old set of Tektro levers, but now I'm using a set of Avid 7's.

I've noticed some housing movement on the front brake, but thats the only thing I can find that could be the problem. It feels like the cable is stuck in the housing. If it happen once I would think it was a bad brake cable, but at this point all the parts are new, the oldest being the bb7's and thats only by a month or so.

I might have thought the zip ties on the mounts were to tight, but it happens on the front line as well.

Any useful info will be greatly appreciated.

[Juanmoretime]

Mine work very well. I'm using Avid Ultimate levers and Alligator I-Link cables and housing. Could there be a burr on one of the ends where you cut the housing?

[jherich]

yes, I did cut one of the cables, but the other is complete with the original ferrels

[Destin]

no offence, but i have to ask this to help you:are you doing the work on your own or taking it to a shop? From the way you talk i assume your doing it yourself...how much expirience do you have wrenching bikes? when you say sticking do you mean the brakes are rubbing, or that the lever doesnt return when you pull it?

[jherich]

None Taken,

And yes I'm wrenching my self, I've worked as a bike tech, although I'm not certified. I've installed lots of types of mechanical brakes, including a set of BB7's. This is the first time I've ever seen this problem.

The lever doesn't return all the way when you pull it, only about 2/3 to 1/2 the way back.

[cobba]

There's a spring tension adjuster on the brake, maybe the spring needs a bit more tension on it. The spring can have more tension put on it by turning the 2mm hex screw clockwise, this will make the brake lever harder to pull but it also make the calliper arm spring back better.

[Destin]

You said the calipers are only a month old? In that case this sounds like a problem inside the caliper itself, and most likley a warranty covered issue. Im thinking it could be a metal burr in one of the bearings inside the caliper from the manufacturing process. Call avid and see what they have to say.

Here is a video on how to install the bb7 properly(direct from avid):
http://www.youtube.com/watch?v=x1kezXQVnLY
I am only posting this so you can be 100% sure you followed the manufacturers instructions. once again, no offence.

[cobba]

Im thinking it could be a metal burr in one of the bearings inside the caliper from the manufacturing process.

I doubt that they'd put the brake together with burrs on the parts.

If the brake calliper opened and closed smoothly without the cable attached, I'd say that there isn't enough tension on the spring. When the cable is attached there's probably enough friction in the brake cable housing to hold the calliper arm back from opening fully, if more tension is put on the spring it should open properly. It mightn't take much extra pressure on the spring to do this.

[jherich]

Very cool, I'll give that a try and see if it makes a difference.

Thanks

[Destin]

Oh duh. I forgot all about the spring tension adjustment on them. woops..sorry about that. , but you would be amazed at how many component manufacturers have problems with quality control, and warranty issues due to burrs. For example this was a big problem with the first batch of specialized dual crown forks that come on the enduros. Last year I had to have a cane creek headset replaced under warranty due to what they said was a "burr". Im sure there are many more products with this problem, but these are the two that i have seen with my own eyes. Your problem is most likely the spring tension.

[jherich]

OK,

It now works perfect.

Thanks for the suggestions.

[jherich]

It was a mixture of two things. On the rear, I adjust the tension per the image posted by cobba, and everything worked well. This is the unmodified Linear Odyssey cable. On the front, adjusting the tension did not help, so I looked through my parts and found an old housing, made sure both ends were clean and burr free, and now everything is perfect.

Thanks for the suggestions.