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How much of an effect would slight but noticeable disc brake rub have on have momentum? On both the front and back wheels when I spin them by hand they pretty much stop after around 1.5 or 2 revolutions when in the dropouts but when I take the wheels out and spin them with the same force, they go through 3 or 4 revolutions. A noticeable brake rub then but it's hardly 'half on' brake feathering.
I was wondering, would the rub get worse while riding? If there was any flex in the wheels it would be at the rim not the disc so that shouldn't be having an effect (I'd have thought?).
I have a rather large trip coming up next week (Wales end to end) and I could really do with getting this sorted.
My resting heart rate is OK, no signs of pending illness, I'm carefully keeping an eye on my riding times and distances so I'm not going too hard but on this particular bike, I'm struggling.
I can only put it down to the brake rub but it just doesn't present itself as being as bad as the effect it is having.
Any help much appreciated.
Those wheels sound like a good way to get lots of high resistance training. My wheels spin for atleast 20 seconds.
Might be a bit obvious but don't you need to sort out your brakes? Whilst riding I suspect it can be different to just spinning them. Try freewheeling in a straight line and crank bike over as far as you can, normally produces a rubbing sound on my bike so flex etc can affect it.
Smee - Member
Those wheels sound like a good way to get lots of high resistance training. My wheels spin for atleast 20 seconds.
Good point, mine spin for ages too (including the £27 Decathlon) maybe knackered bearings and tightening the QR makes it worse?
It's only a gentle shove. I couldn't say how may newtons. I've not had my forearm or wrist calibrated for a while 🙂
I've had the pads out and squirted a bit of stuff (steady) around the pistons. No joy. I don't have time now to get them in the shop so any help would be much appreciated.
To get mine back I take pads out then get a small-ish allan key that will fit in between the pistons and use it to leaver them back, pull brake lever, lever them back, repeat to fade...
Freed off my front brake and been fine since, make sure it it centered (pain in the arse with my "new old stock" IS mount front) and mine were good to go.
Been fine since (did it just before Christmas but not the most prolific rider, survived some decent rides though).
Barca - I take it it'll piss down next week now 😉
Anyway
Pads out, clean everything inside the caliper with an old toothbrush & alcohol [IPA or meths]
Hold back one of the pistons with a tyre lever & pump the other one out a bit - wipe the exposed bit of the piston with a cotton bud soaked in brake fluid & then push it back in.
Do this a few times to get it well lubed - repeat with the other piston[s] & then clean again with the alcohol before putting the pads back in.
How about a bent rotor? Or does it drag for the complete revolution of the wheel?
If its the something dragging on the disc, give the disc a flick with your finger or tap it with a metal object, repeat whilst rotating the wheel. If it makes a dull clonk rather than a ping then something's touching the rotor, if it pings in some places and clonks at others then your disc may be out of true.
I have found that even slight brake rub makes a large difference to how much effort you have to put in, and the chances are that the rub gets worse as you ride, because you heat the rotor/pads, fluid & it all gets even more draggy.
Friend of mine borrowed my old Julies for a newly built bike while his new brakes were being delivered & when we stopped for lunch, the back wheel would only turn half a revolution before stopping. The disc was really hot. Once we'd had lunch, the wheel was much more easy to rotate, but within 10 mins, was back to half a revolution.
Are you using aftermarket pads? I was advised by my LBS to scrape the paint off the edge of the pads that most aftermarket pads seem to have, as my brakes were dragging. I did this, re-seated the calipers just for thoroughness & they now run with no drag at all. The paint around the edge was thick enough to stop the pad retracting when the lever was released.
Thanks for all the help fella's.
The bike is 300 mile old Cube Ltd Race. It seems to have occured over the last week or so. I'll stick some new pads in. Where can I get this alcohol stuff of which you speak? I'm guesing dearest's white wine isn't going to suffice? I'll be inspecting the rotors as well. I'll be gutted if they'rer warped though. A brand new £1000 bike. It would happen just before the ride that I've been working toward all year. Typical. Last years attempt was rained off half way through but no go backs this year. I apologise to all of Wales for the deluge that will ensue.
B&Q or similar will have meths
IPA available from Maplin [amongst others] - there's a Maplin @ Portwood
Although I wouldn't expect a stuck piston on a bike that age
Thanks Uplink (are you local?).
It makes that high pitched brake squeal thing as soon as I move the bike and on the odd occasion whilst riding, the front disc has been high pitched whistling. It drives dogs mad which is funny to see (in my own warped sense of humour).
Clearly I need to fettle. I'm just gutted it's now and not when I get back. I could do without the stress.
I don't think old pads or contaminated rotors can cause brake rub...
You probably wouldn't notice that amount of drag riding along, but check it when you've just got off to see if it's any worse.
Make sure your wheels are seated properly and QR's done up tight enough, as it could be due to a bit of movement happening from braking forces or something causing the brakes to appear out of adjustment.
Thanks Uplink (are you local?).
No but our office is in the same building you work at so I'm there often
It wouldn't hurt to clean the rotors, calipers & pads etc.
I know of another person who has their main office in this building Uplink.
Thanks again for all the tips everyone. Work shall commence at lunchtime. I have the very bike sat next to my desk right now. I don't think my line manager will be impressed but hey-ho.
I know of another person who has their main office in this building Uplink.
Are you sure we're not the one & same?
I can't remember what my login name was pre-hack - I've got that many different ones on forums etc. - it's been erased from my memory
Not from the North East'ish are you?
Yup
Ahh, one and the same then. How's things? Not on the 3rd floor at the moment then? The HRM is still going strong as well.
before you start stripping your calipers have you tried simply re-aligning them?
just loosen the two caliper bolts so the caliper can be waggled about a bit, then with the wheel on the bike squeeze the brake leever. Then whilst continuing to squeeeze tighten up the bolts.
this should centre the pads over the rotor. try again if it doesn't work first time
if it still doesn;t work try some of the more involved solutions above
doing well - just back from a week in Colorado so struggling to get back into work
I've not been there for a few weeks but due in next week for an appraisal 😯
So Wales again next week? - I did that route back in 2003 during a heatwave, it was tough
enjoy
re-alignine the calipers
My rear rotor is slightly warped - it rubs lightly - I ignore it.
Hi Barca, we have this problem from time to time, we do all of the above, but some times needs the levers reach re-adjusting and then a re-bleed, or if you just want you pads a bit further apart, open the bleed screw and push the pistons apart, (or even pull lever just a touch) let a drop or two out and check. I believe this is because the brake fluid has absored some water and then expanded in the line. Ultimately they prob. need a re-bleed but all keeps you going.