I bled my brakes, Hayes Stroker, and they felt great with new pads installed at the same time.
When I bled them, there were very few bubbles coming into the syringe at the lever end so I stopped.
Last night, after a brief pause mid-ride, I set off and there was little brake working when they had been up to that point However, after a couple of seconds of applying the brake, they started to bite again, keen and strong.
They kept working for the rest of the ride.
I would think are town possible scenarios here.
The pads work best when hot/warm?
There is still air in the system and it worked its way back up to the reservoir, bad bleed?
On the latter, when bleeding brakes, do you go off a volume to know that the whole system is flushed, or just until no bubbles come out. If volume, how much is this. The syringes are graduated so easy to monitor.
Thanks
Ps. Uberbike pads, semi-metallic. I have the a2z on the front and followed the same bleeding procedure and they are fine, all the time.
When they were 'a little brake working' did the levers come back to the bar more than normal? if so I'd say there is air in the system.
Did you bed the new pads in?
No. Same lever stroke, just no bite at all. 20 seconds later, after having had them pulled on, they started to bite.
I did (thought) I had bed the pads in....my usual method of solid braking from high speed.
I'm no expert but sounds like its the pads not bedded in properly or pads/rotors contaminated if the lever stroke is the same?
I sometimes find that after a bit of brake bleeding etc they take a couple of stops to get the power back.
However that is after cleaning the rotor with IPA and lightly roughening up the pads to remove any glaze.
If all you've done is bleed them, then I'd suggest the bleed wasn't 100% successful.
till no more bubbles can be made to appear.
if that takes a whole bottle of fluid to dislodge stubborn bubbles in badly designed calipers/levers, then so be it. If you are not introducing air to the system, it has to all come out eventually.
^ sounds like contaminated pads.
It sounds as though you didn't put your brake pads through a proper bed in process. As the new pads are used (bedded in) the pads deposit a layer of material onto the surface of the rotor and at the same time the surface of the pad needs to conform to that of the rotor.
When these two things happen sufficiently your braking power will increase.
If there is excess air in your brake your lever would feel spongy. There is no set amount of fluid required to perform a successful bleed, just keep going until no more air can be withdrawn from the system.
Thanks all.
If the bleed was ok then I'm reluctant to do it again just for the sake of it but then again, I'm off to morzine next weekend and any shortcomings in the system are going to show.
Perhaps another bleed might be worth it, to be sure.
Btw, it is an epic kit I was using but I'm not sure what you mean by not being able to withdraw any more air from the system. It's pushed out isn't it, not pulled out? I'm following your instructions included in the kit!
And would contaminated pads right themselves with use, ie , go from nothing to biting? I always thought that once they were contaminated that was that. I do always remove them when bleeding and after bleeding spray the caliper with disc brake cleaner, wait for it to evaporate and then refit. Fairly careful all in all.
Why did you need to bleed them in the first place?
Spongy. They were last done around 2 years ago. I put new pads in as a matter of course once the pistons are pushed right back into the caliper.
I wonder if it is the pad compound.
By 'withdrawn' I simply meant removed. Most brakes are bled by a bit of push and pull. 😉
Pad compound will affect how your brakes feel and how powerful they are under various conditions. For example resin pads will reach optimal performance sooner than sintered pads due to there being more metal content in sintered pads therefore it takes longer for them to warm up
and to bed in. The trade off is that they will last longer.
Pick your pads to suit your riding style and conditions.
For the record I'm running Uberbike's race matrix pads on all of my brakes now and they're excellent. They last too.
Went out last night with them untouched. They seem to be getting stronger and I didn't have the fade issue so I'm thinking it was a bad bedding in when the pads were fitted.
The bleed kit will be coming to France though, just in case.
Definitely take the bleed kit and fluid out there in case you boil the brakes if for nothing else.
If the brakes werent spongy/pulling to the bar, then it sounds like the pads needed a bit more bedding in to get proper pad material transfer happening.