Disc Brakes - pad touching disc



Hey all,

I purchased a new mountain bike with hayes mechanical disc brakes
(MX-2).

When I collected the bike I lifted up the front wheel and gave it a
spin. As the wheel spun around I could hear the pad touching the disc
at certain points i.e. the wheel was not spinning freely. (The back
wheel does the same thing)

I've tried to readjust the caliper myself but when I get it so that the
pad no longer touches the disc in normal operation, the level travel is
so great that the bike does not stop properly.

I have rang up the store and they've told me it is normal for the brake
pad to be touching a little bit and that after a while the pad will
wear away and no longer be touching, is this true?

To me is just doesn't seem right for the pad to be touching when the
brake is not on.

I've rang up a few different bike stores to get their opinions, some
say it can be touching and others say it should not be touching at all.

Should I take the bike back and get them to fit it properly?

cheers,

Jim
 
<[email protected]> wrote in message
news:[email protected]...
> Hey all,
>
> I purchased a new mountain bike with hayes mechanical disc brakes
> (MX-2).
>
> When I collected the bike I lifted up the front wheel and gave it a
> spin. As the wheel spun around I could hear the pad touching the disc
> at certain points i.e. the wheel was not spinning freely. (The back
> wheel does the same thing)
>
> I've tried to readjust the caliper myself but when I get it so that the
> pad no longer touches the disc in normal operation, the level travel is
> so great that the bike does not stop properly.
>
> I have rang up the store and they've told me it is normal for the brake
> pad to be touching a little bit and that after a while the pad will
> wear away and no longer be touching, is this true?
>
> To me is just doesn't seem right for the pad to be touching when the
> brake is not on.
>
> I've rang up a few different bike stores to get their opinions, some
> say it can be touching and others say it should not be touching at all.
>
> Should I take the bike back and get them to fit it properly?
>
> cheers,
>
> Jim


This happens in a lot of cases - usually, the disks themselves are not quite
true/flat. Doesn't usually pose a problem and often does settle down. Most
car's pads touch the disk slightly - ever had a car wheel off the ground and
truned it while listening? There's usually sounds that indicate this, but
once the vehicle is rolling at any kind of pace it is unnoticeable.

Saying that, I have been able to set mine up with no rub at all (most of the
time!), by very careful shimming (Hope brakes), BEDDING IN WELL, and
carefully tweaking the disk flat where it was slightly out of true (I
suggest you do not try this unless you are knowledgeable and have a good,
solid, practical common sense with mechanical/engineering things, or you
would make it far worse).

Shaun aRe
 
[email protected] wrote:
> Hey all,
>
> I purchased a new mountain bike with hayes mechanical disc brakes
> (MX-2).
>
> When I collected the bike I lifted up the front wheel and gave it a
> spin. As the wheel spun around I could hear the pad touching the disc
> at certain points i.e. the wheel was not spinning freely. (The back
> wheel does the same thing)
>
> I've tried to readjust the caliper myself but when I get it so that
> the pad no longer touches the disc in normal operation, the level
> travel is so great that the bike does not stop properly.
>
> I have rang up the store and they've told me it is normal for the
> brake pad to be touching a little bit and that after a while the pad
> will wear away and no longer be touching, is this true?
>
> To me is just doesn't seem right for the pad to be touching when the
> brake is not on.
>
> I've rang up a few different bike stores to get their opinions, some
> say it can be touching and others say it should not be touching at
> all.
>
> Should I take the bike back and get them to fit it properly?


Your LBS should have included free service for at least 30 days to one year
to lifetime from the purchase time of the bike. The brakes rubbing would
most definitely be included as part of the service.

If you want to learn how to do it yourself, you should go to the Hayes
website to download their manual if it didn't come with your bike:
http://www.hayesdiscbrake.com/pdf/MX2MechDiscInstall4LanguageEnglishWeb.pdf

and also check out Park Tools' website:
http://www.parktool.com/repair/readhowto.asp?id=125
--
Phil, Squid-in-Training