Pulsing brakes

captainfirecat

Hi all

I'm trying to get back into cycling after a spill and thought some nice thick mtb tyres were the way to get my confidence back.

So I bought an entry mtb and I've been pottering around. All good so far, except I have disc brakes for the first time ever and I'm not sure what is normal and what isn't.

For example, when I pull on the brakes (front and back) more than a little they pulse, as in they feel like I'm pulling them on and off even if I give constant pressure. It's almost like I have ABS, but I'm guessing I don't!

So... normal or something odd? It was doing it from day one, and it has had its 6 week service and still does it, and it does the same thing on each wheel, so I'm leaning strongly towards 'expected'!

Any help for a newbie?

Thanks!

#edit#
Haha, I swear I searched 'pulsing brakes' a few times before coming here, but of course I then search after posting and find lots about wavy discs and working as intended comments

Would still appreciate tips on getting used to them though...

jamski

What bike is it and what brakes does it have? It's not something I've heard of before!

cooldad

Bike is?
Brakes are?
Are the rotors warped?

captainfirecat

It's an Apollo Evade (http://www.halfords.com/cycling/bikes/m ... ntain-bike).

cooldad

I'd check for warped rotors, but everything on it is pretty bargain basement, so it could be anything. Don't try anything too gnarly.

captainfirecat

Ok, to be clear I'm not offroading and doing flips on a sub £200 bike, I basically had a spill from my road bike a while back and found when I tried to come back to cycling that every bump and pothole terrified me. So I bought a bottom end MTB on the basis all it needed to do was handle Sheffield roads (which, to be fair, are often about as treacherous as a downhill all terrain section... ) and be able to handle trails (i.e. a bit of gravel and a bit of mud, but pretty flat, so it can go where my road bike can't).

My ride yesterday (which was my first 'big' ride) covered steep downhills on perfect tarmac and where the road was neglected, and a section of light mud/stone chippings and gravel. I had no major issues, no losing control, 90% of the issues I did have were me being overly cautious (I imagine an experienced rider would have blasted down the hills and over the gravel, but I need to lean on my brakes a lot more, hence why I have found this issue). I know the bike is cheap, and that's why I don't expect amazing suspension, gears that change perfectly every time or a light frame. But I would be astounded if Halfords had sold me a bike that exhibited extreme behaviour under moderate braking on tarmac.

I have Googled fork flex (which seems to be an 'issue' with most bikes, albeit to a larger degree with the cheaper ones, though a lot of people seem to experience it on higher end ones). I wasn't aware of that being a thing, but now I know I can adapt my style around it. I would be very surprised if both my rotors were warped, especially after two different people have worked on them and the bike has done less than 100 miles. I would be prepared to believe they weren't on perfectly straight, but again that seems to be a thing you have to overcome, not something you can avoid on bikes.

I assume(?) you were both trying to help, but you came across as terse and a bit snobbish. This is the beginner's forum, a lot of us will have cheap bikes and will have little to no knowledge of cycling. Replying to someone by saying 'well you get what you pay for, could be anything' or 'probably #technical term with no explanation# because you have a super cheap bike' doesn't help much and just made me panic that I had a serious issue. As a newbie I would have preferred 'You've obviously got a low end bike so a lot of issues experienced by riders will be much more noticeable with you. It's possible that the rotors are off somehow, but given you say you've just had the bike serviced it seems unlikely. Much more likely is that you are experiencing fork flex, where the forks move under stress, such as when braking. A lot of bikes have this to some degree, but as I say with you having a cheaper bike you will feel it more. Have a Google and there will be some tips as to how to compensate for it.'

Uber_Pod

After reading the forum for a little while, you kind of get used to some of the personalities.

You say you had the bike serviced and it did the pulsing brake thing before and after. What did the people who did the servicing (Halfords?) say about it?

joncomelately

Good rant, like it.

I've got discs on both my bikes (not MTBs, but a CX and a road). The CX bike came with bent rotors and has never 'pulsed' - all I got was brake rub at a specific point, but the bite never changed once I'd started braking. My £1500 road bike with a carbon fork (which isn't overly cheap) and hydraulic discs pulses on both front and rear brakes with new rotors which are straight, but I've not actually had a problem stopping. So from my limited experience I wouldn't worry too much about it if you can actually brake OK, for me it just seems to be the outcome of a particular set up.

(He says, praying his fork and/or stays don't explode next time he brakes...)

cooldad

Only terse and snobbish? People normally just call me an out and out d1ck, so thank you.

cooldad

But with all due respect to Halfords, I doubt (m)any bike shops would check for things like rotors in a service unless they were specifically asked. It's normally just a bit of adjusting, a smidge of lube, and checking the tyres and pads still have some life left.

Certainly very few will actually test ride a bike, just stick it on a stand and fiddle.