Just collected bike ftom LBS - brake still rubbish!

grellboy

Über Member
I installed some new (mechanical) disc pads a few days back and couldn't really get much stopping power off them, so save messing around I dropped at lbs for them to tune in. A friend picked it up for me today and I've just tried it out and to be honest there is barely any improvement! If I upend the bike and spin the wheel the brake works fine (perhaps a little slow to grip but reasonable). However, when I'm actually on the bike the brake is pretty useless still. I'm no whippet but 85kg is surely not such a ridiculous weight to render the rear brake ineffective is it? Is it s bedding in thing? Or is this just a myth?
 

cosmicbike

Perhaps This One.....
Moderator
Location
Egham
Bedding in yes, do about 10 hard stops from 10-15mph, release the brake before you stop completely. Bear in mind the rear brake is not as effective as the front, treat the rear as a slow you down device, the front as the one doing the actual stopping.
 

vickster

Legendary Member
Indeed if no better after trying to bed in 👍 And checking the adjustment, ie that the pads are close enough to the rotors
 

roley poley

Senior Member
Location
leeds
If they were the promax you posted on another thread asking for replacement pads I swapped the same brakes for avid bb7 and was very happy I changed ..£60 from spa cycles for a caliper and rotor... all brakes should do a good job but I couldn't get what I wanted out of the promax render-r no matter how hard I faffed and fettled :blush:
 
OP
grellboy

grellboy

Über Member
If they were the promax you posted on another thread asking for replacement pads I swapped the same brakes for avid bb7 and was very happy I changed ..£60 from spa cycles for a caliper and rotor... all brakes should do a good job but I couldn't get what I wanted out of the promax render-r no matter how hard I faffed and fettled :blush:
Thanks for the replies (everyone!) they are indeed the promax. I'll try everyone's suggestions and then maybe look at replacements if no improvement. Now, when do those £50 vouchers materialise? 😂😂
 

glasgowcyclist

Charming but somewhat feckless
Location
Scotland
This document explains the proper burn in procedure...
 

Attachments

fossyant

Ride It Like You Stole It!
Location
South Manchester
Bedding in is important as others have said. When I changed to Uber Race Matrix I re-bedded them in as they were a different compound (cleaned of discs first) - I stick with Race Matrix now.
 

Smokin Joe

Legendary Member
It is the rear brake, exactly how ineffective is it? I rarely touch mine even on the motorbike, it's handy for scrubbing a bit of speed off on loose or wet surfaces but it is never going to bring you to anything like a quick stop, there isn't enough weight on the back of a bike and you'll just lock up if it is anywhere near too sharp. The front brake does the stopping.
 
Ignore the suggestions to use cleaning fluids etc, that won't cut it. If you have already ridden the bike without bedding the brakes in properly, you'll have to start again with brand new disc pads, no point trying with ones you've already used as there's a thin layer of material on fresh pads which has to be transferred cleanly and evenly to new or freshly sanded down discs (if sanding down, make sure you DO clean them with white spirit or isopropanol and a clean lint free cloth). If you don't do this by the book, you'll never get optimal transfer to the discs. Good news is you don't need to bin the existing pads, just save them until the next pair are worn. You can ask a good bike shop to do the bedding in process for you, but personally wouldn't trust anyone but myself to do this right as some shops don't know or care about it. You need to get the bike up to speed without using the brakes, then brake hard but without coming to a complete stop, accelerate again and repeat 10 times. Do this process for each wheel. This is easiest to do in an empty car park or on a long descent if you have one nearby, or do it on the open road with care of motorists around you. Before I appreciated all this, I unwittingly botched the bed in process on the rear wheel, but after some hard braking on a downhill stint, managed to get it near good enough, but it was never right until I started with fresh pads. Few people realise how critical the proper process is to getting the best out of their brakes from day 1.
 
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Darius_Jedburgh

Senior Member
Just remember to bed your brakes properly. Every bike that leaves a bike shop is unsafe to ride until you have ridden down Alpe d'Huez 5 times.
The shops don't tell you this because that would stop sales. They also won't bed them in for you because they are not allowed to ride your bike.
Read the mfg handbook to see what they say about bedding in brakes. You might be surprised.

Similarly with new pads. Even Shimano won't tell you to spend an inordinate amount of time bedding in brakes because that would imply that they are supplying pads that are unfit for purpose.

In fact don't ride your bike anywhere until you have bedded in your brakes. If the brakes fail you will be liable.
 
until you have ridden down Alpe d'Huez 5 times.
Slight exaggeration in my view, but the principle is bang on. :okay:

As long as you get the transfer to the discs right, you'll have good enough performance to start with, it will improve over the course of the next few rides. Just be mindful of your stopping distance for the first few rides. Darius is right about it being unsafe if you are not careful.
 
OP
grellboy

grellboy

Über Member
Ignore the suggestions to use cleaning fluids etc, that won't cut it. If you have already ridden the bike without bedding the brakes in properly, you'll have to start again with brand new disc pads, no point trying with ones you've already used as there's a thin layer of material on fresh pads which has to be transferred cleanly and evenly to new or freshly sanded down discs (if sanding down, make sure you DO clean them with white spirit or isopropanol and a clean lint free cloth). If you don't do this by the book, you'll never get optimal transfer to the discs. Good news is you don't need to bin the existing pads, just save them until the next pair are worn. You can ask a good bike shop to do the bedding in process for you, but personally wouldn't trust anyone but myself to do this right as some shops don't know or care about it. You need to get the bike up to speed without using the brakes, then brake hard but without coming to a complete stop, accelerate again and repeat 10 times. Do this process for each wheel. This is easiest to do in an empty car park or on a long descent if you have one nearby, or do it on the open road with care of motorists around you. Before I appreciated all this, I unwittingly botched the bed in process on the rear wheel, but after some hard braking on a downhill stint, managed to get it near good enough, but it was never right until I started with fresh pads. Few people realise how critical the proper process is to getting the best out of their brakes from day 1.
"Without coming to a complete stop"? Just tried that and rear brake alone barely slowed me at all, so no chance of a complete stop (or any stop in fact!) at all. As such I will have a fiddle myself tonight? With this in mind, am I best of tightening up the cable (ie the left hand pad - rear view - or dialling in the right hand pad using the allen bolt - or both?
 
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