hi folks,

I’m getting a vibration from the front of my bike when i’m heavy braking. I’ve switched the brakes over between some deores and juicy’s and the exact same thing is happening (note: neither need bleeding
before that is suggested, it was the first thing i did).

Looking at the disc (160mm cheap shimano) there is no warping at all. where should i look next to see what is causing it?

unusual for it to be the front. I had this problem on the back of my bike for ages.

there could be some contamination on the disc. If so it would be really annoying as you may have now comtaminated the pad on new brake you have just put on. Could you try swapping in the disc from the back of your bike and a fresh set of pads and see if that cures it?

Other thoughts – is there any play in the fork? I guess that could start vibrating when you hang on the brakes

what about the brake adaptor – did you swap that as well? If it were cracked or something it could cause vibration

headset is properly adjusted?
try another disc that is ok. the rear, for example.
EDIT: WOT HE SAID^^

I should have said that i’ve cleaned the brake disc thoroughly, especially before installing the juicy’s which had brand new pads.

I didn’t swap the brake adapter, i’ll try that later to make sure, but i have a horrible feeling it’s the headset or the fork.

What’s the best way to check the headset?

I want to get this sorted as i’m selling the bike to my mate and don’t want to leave him loads of crap to deal with!

Fork bushes?

excuse my ignorance, but what are fork bushes and how do i test if it is them or not?

They’re the bushes in your fork that the stanchion slides up and down in. If you’re getting a kind of fore / aft “flutter” from the front under heavy braking (you’ll probably be able to see it) it could well be the bushes. It’ll tend to be more noticeable on tarmac or smooth surfaces.

If you rock the bike back and forth with the front brake on you *should* be able to get an idea where any movement’s coming from – headset, forks or brakes.

@flyingmonkeycorps thank you!

that ‘flutter’ is probably the best description of the problem and yes it is most noticeable on tarmac

That would be my guess then, especially if you’ve tried different brakes.

Stolen from here:

Turn the bike upside down resting on the seat and handlebars. Remove the front wheel. While standing on the grips to hold the bike stationary grab the fork lowers and try to rock them back and forth, side to side. You should have no discernable play.

if you hold the front brake on, push the bike backwards and forwards gently you may be able to feel small ‘clunk’ motion as it rocks. If you do it is either the fork bushings or headset.

forks you should be able to tell using the method flyingmonkeycorps describes above. If it is the headset you should be able to feel it by resting your finger on the upper headset assembly while rocking the bike backwards and forwards, if you can feel movement it needs adjusting (or replacing if it is knacked)

@flyingmonkeycorps @nosedive

thanks, really useful advice. I’ll check when i get home tonight

Fingers crossed it’s the headset, that’s pretty easy to sort. Though if it’s bushings do a bit of digging, some folk suggest that a bit of play is normal, depending on the forks. Getting them services should sort it though.