Disc brake problems...

[Charlie Johnson]

Hi all, This morning I was riding my week-old bike and the front disc brake was really inefficient for some reason. It was working fine last night but today it seems to 'bite' quite quickly initially and slow me down but the more pressure I put on the lever, the worse it seems to perform. Anyone know why this might be the case? If it helps, the brakes are Shimano BR-R517 mechanical disc brakes with 160mm rotors.

 

[compo]

On a week old bike I would take it back to the dealer to get them to check out the brakes. It may just be a bit of stretch in the cable. If everything is in order mechanically I would give the disc rotor a good clean with brake cleaning solvent, available at great expense from bicycle shops or more cheaply from garages or motor spares shops. It is worth doing that periodically anyway.

 

[Charlie Johnson]

HI Compo, thanks for the reply. I actually tightened up the cable as there was a little too much play in the lever so I don't think that's it. I'll give the solvent a go - a bit of petrol should do the trick I reckon

 

[compo]

Your call. Personally I wouldn't use petrol.

 

[mrbikerboy73]

Petrol may contaminate the pads so I'd give it a miss. Brake cleaner is only a few quid.

 

[wisdom]

As with compos reply.i would take it back and ask them to take a look at it, could be something failing.

 

[Mr Haematocrit]

Petrol it will leave a residue.... Look around petrol station forecourts they are stained from fuel spillage

 

[T.M.H.N.E.T]

Let the pads and discs bed in!

 

[Pale Rider]

Let the pads and discs bed in!

Good idea.

The bedding in process can be accelerated by a few sharp stops, but that only works if the bike is still new.

As others have said, dedicated brake cleaner is a good investment.

I have a Muc-Off one which was about £6 and will last me forever.

An alternative if bedding in fails is to abrade the disc.

Light emery paper will do that, or an old mountain bikers' method is to deliberately smear the disc with a bit of mud and let the grit in the mud do the job for you.

 

[Custom24]

As others have said, dedicated brake cleaner is a good investment.

I have a Muc-Off one which was about £6 and will last me forever.

Is that a solvent you mean, or something else? I find isopropyl alcohol more cost effective than brake cleaner.

 

[Pale Rider]

Is that a solvent you mean, or something else? I find isopropyl alcohol more cost effective than brake cleaner.

I use this one:

http://www.wiggle.co.uk/muc-off-dis...erid=googwig&gclid=CM784MObob4CFdShtAodiwwASA

As I mentioned, a couple of squirts now and again means it will last years.