Disc brake help
Discussion
Hello chaps,
Went on an epic 30 mile off road/on road today and it was great, I went very fast and had lots of fun!
However my disc brakes are s
t, and I know they shouldn't be as bad as they are. Basically they won't lock the wheels, and from previous bikes (Hayes HFX 9 Carbon) I know that if I pull in the front hydraulic brake it should lock the wheel. Mine don't, my pals V brakes did a better job..
They are newish looking Shimano Deore Hydraulics. They also squeak a lot if you use them for sustained periods.. What can I do?
Rockhopper Specialized bike btw, from 2007.
Went on an epic 30 mile off road/on road today and it was great, I went very fast and had lots of fun!
However my disc brakes are s
t, and I know they shouldn't be as bad as they are. Basically they won't lock the wheels, and from previous bikes (Hayes HFX 9 Carbon) I know that if I pull in the front hydraulic brake it should lock the wheel. Mine don't, my pals V brakes did a better job..They are newish looking Shimano Deore Hydraulics. They also squeak a lot if you use them for sustained periods.. What can I do?
Rockhopper Specialized bike btw, from 2007.
If you drop the wheel out of the bike you can usually see in to the caliper enough to see if there is anything left on the pads.
It might be that oil or something has got on to the discs and they just need a good clean with alcohol or disc cleaner. Might be worth a try?
It might be that oil or something has got on to the discs and they just need a good clean with alcohol or disc cleaner. Might be worth a try?
Edited by craig_s on Monday 13th April 22:52
Yeah, if you reckon the lever travel and feel is OK, you've probably contaminated your pads. Clean the pads and discs with disc cleaner/IPA spray, or change the pads.
Try http://superstar.tibolts.co.uk/ for cheap pads - either direct from website, or from ebay. They have an ebay store, and it's cheaper to buy 4 pairs. Very quick delivery too.
Try http://superstar.tibolts.co.uk/ for cheap pads - either direct from website, or from ebay. They have an ebay store, and it's cheaper to buy 4 pairs. Very quick delivery too.
If the throw of the lever is fine, ie: it doesn't come all the way back to the handlebar, then it sounds like the pads are contaminated. Is this the first time you've used the brakes? If it is did you clean the rotors before using them?
To clean / decontaminate the pads you can soak them in panel wipe, then heat them in a low oven (50C) but there's no guarantee that'll work.
You'll need new pads and to give the rotors a good clean with an alcohol or solvent based cleaner. You can buy disc cleaner or panel wipe from most motorfactors but petrol will work too.
The squeak is either contamination burning off or a slight mis-alignment. The later is nothing to worry about, the former will be cured by the above.
To clean / decontaminate the pads you can soak them in panel wipe, then heat them in a low oven (50C) but there's no guarantee that'll work.
You'll need new pads and to give the rotors a good clean with an alcohol or solvent based cleaner. You can buy disc cleaner or panel wipe from most motorfactors but petrol will work too.
The squeak is either contamination burning off or a slight mis-alignment. The later is nothing to worry about, the former will be cured by the above.
Pads VERY easy to change, just make sure you properly clean the rotor first before fitting the new ones to avoid cross-contamination (which could be why your old ones aren't working well). Superstar components ones are pretty good.
Squealing: put a dab of copper-slip/anti-seize on the REAR of the pad (where the piston pushes it) - can stop the vibrations in the pad that cause the squealing. f you do this, just be careful not to get it on the pad/rotor obviously!
If they feel firm at the bar, then they don't need bled.
If they feel soft at the bar, give them a bleed (surprisingly easy, look on youtube for "Shimano Deore brake bleed" vids).
Could it be you're lacking power? Might be worth trying bigger rotors? depends on your, ahem, size and also your riding style. I use Shimano XT hydraulics on all my MTBs: 180fr/160rr for "normal" riding and 203fr/160rr on my 6" travel big bike. More than enough power to lock either wheel with one finger and I'm a tad over 80kgs.
Squealing: put a dab of copper-slip/anti-seize on the REAR of the pad (where the piston pushes it) - can stop the vibrations in the pad that cause the squealing. f you do this, just be careful not to get it on the pad/rotor obviously!
If they feel firm at the bar, then they don't need bled.
If they feel soft at the bar, give them a bleed (surprisingly easy, look on youtube for "Shimano Deore brake bleed" vids).
Could it be you're lacking power? Might be worth trying bigger rotors? depends on your, ahem, size and also your riding style. I use Shimano XT hydraulics on all my MTBs: 180fr/160rr for "normal" riding and 203fr/160rr on my 6" travel big bike. More than enough power to lock either wheel with one finger and I'm a tad over 80kgs.
Thanks for that, I will check pads when I get home, but tbh I think I will get some anyway, they're cheap and it sounds like they are the problem.. Along with dirty discs.
Might be lacking power, I am a big bloke 90kg, but its a very light bike and they feel like they could be a world better! Granted the HFX ( Carbons I had were far more powerful and had bigger rotors, but these are worse than V's at the minute..
Might be lacking power, I am a big bloke 90kg, but its a very light bike and they feel like they could be a world better! Granted the HFX ( Carbons I had were far more powerful and had bigger rotors, but these are worse than V's at the minute..
As already said, pads are easy to change but don't forget to clean the rotors. If you take them off the wheels to clean them you'll need to wipe them over again once you've refitted them too.
Rotor size is unimportant. If the brakes are set-up and working correctly, locking a wheel up can be done by a child. Put simply - and I mean simply - if V-brakes are the equivelant of drum brakes on a car. Hydraulic (and Avid BB-7 cable) discs are like F1 carbon ceramic brakes.
Again, I'd suggest visiting your local bike shop at a quiet time for some face to face advice on cleaning and maintaining your brakes. Or ask a kindly PHer to pop by for a beer.
Rotor size is unimportant. If the brakes are set-up and working correctly, locking a wheel up can be done by a child. Put simply - and I mean simply - if V-brakes are the equivelant of drum brakes on a car. Hydraulic (and Avid BB-7 cable) discs are like F1 carbon ceramic brakes.
Again, I'd suggest visiting your local bike shop at a quiet time for some face to face advice on cleaning and maintaining your brakes. Or ask a kindly PHer to pop by for a beer.
mk1fan said:
Rotor size is unimportant. If the brakes are set-up and working correctly, locking a wheel up can be done by a child. Put simply - and I mean simply - if V-brakes are the equivelant of drum brakes on a car. Hydraulic (and Avid BB-7 cable) discs are like F1 carbon ceramic brakes.
Don't totally agree with you there. Although I CAN lock the brakes with a 160mm rotor on the front, they're still not suitable for me for normal riding. As soon as the brakes have been used a few times, a 160mm front setup will quickly knacker/glaze the pads and overheat the fluid! 160mm isn't big enough for everyone or all types of riding, even with the UK's limited descents.a11y_m said:
Don't totally agree with you there. Although I CAN lock the brakes with a 160mm rotor on the front, they're still not suitable for me for normal riding. As soon as the brakes have been used a few times, a 160mm front setup will quickly knacker/glaze the pads and overheat the fluid! 160mm isn't big enough for everyone or all types of riding, even with the UK's limited descents.
I wasn't saying that a 160mm rotor was the right size for the type of riding the OP is doing I was saying that regardless of the rotor size disc brakes should easily lock up a wheel. If it doesn't there's a problem - one that isn't going to be cured by swapping the rotor for a larger one. At 14-stone I can run a 160/140mm set up on an XC bike without issue but my DH bike needs 203/185mm set-up.okgo said:
Rotor size obviously is important, bigger rotor means more stopping power, works with cars the same it does bikes, but yes when these have been fixed they should be fine for me.
The disc may be bigger but the braking surface is exactly the same, albeit with greater torque and more heat dissipation. I don't think its quite the same principle as a vehicle disc brake, which will have bigger pads.Not always the case with cars. I can fit bigger discs from the VW range but keep the same calliper and pads. What tends to happen is that people upgrade the callipers and discs on a car.
On bicycles it's the additional leverage on the hub that the larger rotor gives which improves things. They FEEL more powerful but they aren't, they're just have better torque.
On bicycles it's the additional leverage on the hub that the larger rotor gives which improves things. They FEEL more powerful but they aren't, they're just have better torque.
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