Disc Brake Adjusting

[Downward]

Hi I am having to pull my Rear Brake lever quite far towards the handlebars before it bites.

Any ideas how I can adjust it so I don't need to pull as far ??

The Front discs are fine.

 

[spandex]

1st you are using your back brake to much. When you start to brake start with your front it is much safer.

2nd what brakes do you have???

 

[GilesM]

Downward

Are they hydraulic or cable brakes?

If Cable I would just tighten the cable with the adjusters.

If Hydraulic, they could be a small adjuster on the brake lever, this would be a small grub screw that you need to use a small (1.5/2mm) allen key, this will move the bit position away from the bars (or towards the bars if you turn it the wrong way). It could also be that your pads are worn, or the brakes need bleeding.

As for too much rear brake use, if you are riding down steep hills off road, alot, then stick with more back brake use, it's better than using your face as a brake.

 

[jpembroke]

I concur with Spandex. Many pro road cyclists have bikes set up with dual pivots on the front and single pivots on the back. This produces differential braking power with a front bias. If you watch them descend at 50mph down 20km of hairpins they hardly touch the back brake. Many mountain bikers have a larger disk at the front than the rear for the same reason. I remember having a chat with an elite MTB XC/Cyclocross rider - one of the best in the UK. His advice was to leave the back brake alone - just feather the front and don't lock it up. You control the bike with the front brake; whereas the back will easily lock up and send the bike off course.

As for your brake problem, I'd try bleeding it.

 

[GilesM]

I concur with Spandex. Many pro road cyclists have bikes set up with dual pivots on the front and single pivots on the back. This produces differential braking power with a front bias. If you watch them descend at 50mph down 20km of hairpins they hardly touch the back brake. Many mountain bikers have a larger disk at the front than the rear for the same reason. I remember having a chat with an elite MTB XC/Cyclocross rider - one of the best in the UK. His advice was to leave the back brake alone - just feather the front and don't lock it up. You control the bike with the front brake; whereas the back will easily lock up and send the bike off course.

For many situations I would agree, both my MTBs have bigger disks on the front, but I can guarantee that too much front brake in the wrong place will result in a trip over the bars, happy to be proven wrong, also happy to watch you try to prove me wrong, as long as I can choose the location (I have a good one in mind) and watch.

 

[jpembroke]

For many situations I would agree, both my MTBs have bigger disks on the front, but I can guarantee that too much front brake in the wrong place will result in a trip over the bars, happy to be proven wrong, also happy to watch you try to prove me wrong, as long as I can choose the location (I have a good one in mind) and watch.

yes, as I say, feather the front brake, don't lock it up. My front pads always wear quicker than the back ones and I've never been over the bars. I ride XC, road, and race cyclocross to a reasonable standard. I don't do downhill or BMX where things are probably different. I can see that a back brake helps you pull the bike round tight turns at speed but if I rode alpine road descents on the back brake it'd take me twice as long and i'd probably nearly lose it on every hairpin. Horses for courses I guess but for me front brake is more important than the rear. If it was the other way round then my mtb would have the big rotor on the back.

 

[spence]

There are situations when rear braking is more appropriate, steep loose descents come to mind where you need to adjust your line but not lose momentum. The rear rotors are usually smaller (as with most cars) as 70% plus of the braking effort is placed on the front due to weight transfer as an equal force is applied to the levers. A sort of natural brake balance if you like.

But getting back to the question.

Yes, what system do you have? I think all new setups are open systems ie having reservoirs to allow for expansion of the fluid when hot and not force the pads onto the rotors. With this the pads also auto adjust for wear, the same as the disk pads on your car. The hydraulic system should take up the "slack" but if the pads are very worn there may be excessive travel. As stated previously, some levers can be adjusted but this may only be for reach not effecting the actual travel of the master cylinder piston. Certainly the case on my M4's and Mini's.

Check the pads for wear. Change if necessary.

Another cause of excess movement or a spongy feel is the fluid in the system. It may just need bleeding if air has entered the system or changing completely if a couple of years old. Standard DOT 4 or 5 fluid will absorb moisture over time reducing its capacity to function. May not be the case for mineral fluid used by Shimano and others.

Also check the alignment of the caliper paying close attention to getting the pads centralised. It's ideal to have the pistons/pads on each side traveling the same distance before contact with the rotor. If one side has to move further than the other this can cause a soft/long travel lever.

 

[02GF74]

There are situations when rear braking is more appropriate, steep loose descents come to mind where you need to adjust your line but not lose momentum.

yep. sometimes you need to lock the rear wheel and come down in a controlled slide; applyng the front brake would have you over the bars

 

[Downward]

Hi I have Shimano 485 Hydraulic Discs apparently !

 

[spence]

OK.

First I don't believe there is an adjustment on the lever.

Second check the pad condition and alignment of the caliper.
Shimano instructions here http://techdocs.shimano.com/media/t...002/SI_8ES0A_002_En_v1_m56577569830616405.pdf

If you feel they may need bleeding then instructions here: http://techdocs.shimano.com/media/t...001/SI_0040A_001_En_v1_m56577569830615981.pdf

Remember they use mineral oil available from your LBS not DOT fluid as used in your car. Using DOT fluid will trash the seals.

One thing you may try before bleeding (or after) is strapping up the levers over night. Tie the levers back against the bars with some string or zip ties. This should migrate any air in the system back to the reservoir.

 

[Downward]

OK.

First I don't believe there is an adjustment on the lever.

Second check the pad condition and alignment of the caliper.
Shimano instructions here http://techdocs.shimano.com/media/t...002/SI_8ES0A_002_En_v1_m56577569830616405.pdf

If you feel they may need bleeding then instructions here: http://techdocs.shimano.com/media/t...001/SI_0040A_001_En_v1_m56577569830615981.pdf

Remember they use mineral oil available from your LBS not DOT fluid as used in your car. Using DOT fluid will trash the seals.

One thing you may try before bleeding (or after) is strapping up the levers over night. Tie the levers back against the bars with some string or zip ties. This should migrate any air in the system back to the reservoir.

Thanks
Will give that a try.