Yet Another Cycling Forum

General Category => The Knowledge => Topic started by: alecstilleyedye on March 28, 2008, 01:18:23 pm

Title: odd noise from front end of the bike under braking
Post by: alecstilleyedye on March 28, 2008, 01:18:23 pm
my alu roadbike has developed a noise like someone tapping on the frame under front braking. the brake block pads need replacing, but other than that i'm a bit perplexed.  ???

all advice welcome.
Title: Re: odd noise from front end of the bike under braking
Post by: MSeries on March 28, 2008, 01:19:26 pm
You rim might have started to split, the 'tap' being when the split passes the brake block.
Title: Re: odd noise from front end of the bike under braking
Post by: rafletcher on March 28, 2008, 01:39:35 pm
Or sometimes it's the join in certain rims that can have this effect - assuming it's at wheel revolution speed.
Title: Re: odd noise from front end of the bike under braking
Post by: MSeries on March 28, 2008, 01:49:17 pm
Or sometimes it's the join in certain rims that can have this effect - assuming it's at wheel revolution speed.

I was thinking of the join coming apart actually.
Title: Re: odd noise from front end of the bike under braking
Post by: LittleWheelsandBig on March 28, 2008, 02:13:28 pm
I was thinking of the join coming apart actually.

Difficult in a built wheel, there is a lot of compression in the rim from the spoke tension.
Title: Re: odd noise from front end of the bike under braking
Post by: andygates on March 28, 2008, 02:18:34 pm
Easy to identify: is the tapping regular, with the period matching the period of wheel rotation?
Title: Re: odd noise from front end of the bike under braking
Post by: MSeries on March 28, 2008, 02:25:13 pm
I was thinking of the join coming apart actually.

Difficult in a built wheel, there is a lot of compression in the rim from the spoke tension.

It happens, did to me. one side of the join had a split on the breaking surface which allowed  part of the breaking surface to be higher than the part it was once joined to. I realised this because of a click when I braked.
Title: Re: odd noise from front end of the bike under braking
Post by: LittleWheelsandBig on March 28, 2008, 03:12:13 pm
To my mind, that is not the joint coming apart.  It is the part of the rim trying to break off, usually because of excessive wear.

Separated by a common language, I guess.
Title: Re: odd noise from front end of the bike under braking
Post by: alecstilleyedye on March 28, 2008, 03:56:27 pm
Easy to identify: is the tapping regular, with the period matching the period of wheel rotation?
no, it's more when brakes are applied, and then released. effect not observed when the brakes are applied with the bike stationary.
Title: Re: odd noise from front end of the bike under braking
Post by: andygates on March 28, 2008, 04:18:59 pm
That suggests that there's slack in the caliper, pads or headset - the "tick" is the slack being taken up to its endstop. 

With the bike stationery on a firm surface, apply the brake and rock back and forth.  Can you reproduce the sound that way?  Can you see anything moving?  To check the headset, put your fingers over the frame and fork parts of the lower headset race - they're more sensitive to movement than your eyes are.

You say the brake blocks are on their way out - I'd change 'em and see if that sorts it :)
Title: Re: odd noise from front end of the bike under braking
Post by: alecstilleyedye on March 28, 2008, 04:23:43 pm
cheers all  8)
Title: Re: odd noise from front end of the bike under braking
Post by: Hot Flatus on March 29, 2008, 10:51:44 am
Ditto andy gates, first port of call check headset for play, and check to see if caliper bolt is tight
Title: Re: odd noise from front end of the bike under braking
Post by: clifftaylor on March 29, 2008, 11:05:44 am
Or possibly a bit of aluminium stuck in the brake pad, and ticking every time it reaches the join.
Title: Re: odd noise from front end of the bike under braking
Post by: alecstilleyedye on March 29, 2008, 06:52:57 pm
i've got some new pads so i'll see if that makes a difference. thanks for all the advice, i'll be sure to check the headset for movement too. as i'm at home with the kids tonight, and tomorrow i'll be watching the worlds, sorry helping mrs alecetc prepare for going away on monday, so i won't have a chance to test ride the new pads.