replacement bolts

[weely]

need to replace the bolts that fix my disc brakes to the frame , any ideas what size they are (m8 ,m5 ect)

 

[smokeysmoo]

The make and model of the brakes would probably help folk to help you with this.

 

[weely]

I think there all a standard size mate but would like an assortment anyway.

 

[Lanzecki]

Take the old bolts with you. You can compare the pitch and diameter that way.

 

[Pauluk]

What Lanzecki says, but mine are M5. I believe a 4mm key fits a M5 cap head if you want to try that, but taking one along to the shop is best bet to get it right first time.

 

[Lanzecki]

Dont assume that a 4mm key fits an m5 bolt though. I bought some bottle cage bolts from 2 different people. They used different sizes of key.

 

[Pauluk]

It's really annoying that there seems to be no fixed relationship between cap head/key size and bolt thread size. I guess there's no standard and it all depends on what tooling the various manufacturers use.

 

[Skyfoil]

Allen bolts do have standard sizes, but that doesn't mean manufacturers have to use them. For example, the standard hex size for an M5 bolt is indeed 4mm, but I have seen many other variants.
Many disk mountings, bottle holders and mudguard fixings are M5, but always check first.