Hydraulic disk brakes - what's up here?
Discussion
I have a feeling I've asked about this before on here but I can't find the post and the issue isn't fixed years later!
Basically, I bought a used Giant Talon Mountain bike several years ago. Has hydraulic disk brakes at both ends but they've always been crap. A couple of years ago, I embarked on fixing this. Bought new pads and hydraulic oil and a bleeding kit. The pads were cheapo ones but had been recommended. I'd now question whether I should have spent more!
Anyway, the issues. Firstly, braking power is crap. I can get nowhere near locking a wheel on the move. It takes loads of effort to even try that and if I do, both ends honk/squeal tremendously. I thought I'd got them well bled and aligned but clearly something is very wrong.
Is it time to take this somewhere to sort or is there some basic diagnostics or adjustment work I can follow. Doesn't really feel safe to ride at the moment and brake noise is quite antisocial!
Basically, I bought a used Giant Talon Mountain bike several years ago. Has hydraulic disk brakes at both ends but they've always been crap. A couple of years ago, I embarked on fixing this. Bought new pads and hydraulic oil and a bleeding kit. The pads were cheapo ones but had been recommended. I'd now question whether I should have spent more!
Anyway, the issues. Firstly, braking power is crap. I can get nowhere near locking a wheel on the move. It takes loads of effort to even try that and if I do, both ends honk/squeal tremendously. I thought I'd got them well bled and aligned but clearly something is very wrong.
Is it time to take this somewhere to sort or is there some basic diagnostics or adjustment work I can follow. Doesn't really feel safe to ride at the moment and brake noise is quite antisocial!
Just because they are hydraulic, doesn’t mean they are good.
I’ve just (last night) bought a new (to me) eMTB. Waaay better than my existing eMTB, but the brakes on the new bike are shocking - almost no bite, especially on the front. On my existing bike, the brakes are amazing - they are probably capable of putting me over the bars.
What brakes does your bike have?
I’ve just (last night) bought a new (to me) eMTB. Waaay better than my existing eMTB, but the brakes on the new bike are shocking - almost no bite, especially on the front. On my existing bike, the brakes are amazing - they are probably capable of putting me over the bars.
What brakes does your bike have?
Bedding in is quite critical. I just changed the pads and fluid on my Orange Alpine before a weekend MTB trip in the Howgills.
Some big descents were ideal for progressively dragging on the brakes to bed them. Half way through the first day the change was like night and day - loads of bite an great modulation.
I would take out the pads and clean them on some fine wet and dry on a flat surface. Also linish the rotors with the same, then clean everything with brake cleaner and start again.
If they are SLX I find them a bugger to bleed even with the right kit. The tap tap tap on the lever once you have done the bleed was a game changer - little bubbles kept emerging and the levers firmed up but they only got really firm once the pads were bedded in.
My son has a Talon and the brakes are good so they can be made to work well.
Oh, and follow a correct bedding in procedure after that
Some big descents were ideal for progressively dragging on the brakes to bed them. Half way through the first day the change was like night and day - loads of bite an great modulation.
I would take out the pads and clean them on some fine wet and dry on a flat surface. Also linish the rotors with the same, then clean everything with brake cleaner and start again.
If they are SLX I find them a bugger to bleed even with the right kit. The tap tap tap on the lever once you have done the bleed was a game changer - little bubbles kept emerging and the levers firmed up but they only got really firm once the pads were bedded in.
My son has a Talon and the brakes are good so they can be made to work well.
Oh, and follow a correct bedding in procedure after that
Edited by Lotobear on Thursday 9th July 09:02
Thanks folks. I'm certain this is not just how they should be. There is no bite at all. It takes a lot of effort to stop the bike at all. I'd be amazed if they were like that new! Looks like the brakes are Giant's own brand. Can't see any other logos on them. Can't recall what pads I fitted last time though I have to admit I'm tempted to replace those anyway and start over with a known quantity. Backstop option is definitely to take it to an expert but I like to do my own maintenance on everything and always keen to learn so not quite ready to do that yet.
So I think I'll take everything apart again. Replace pads. Pay attention to alignment. Replace and bleed fluid and pay a lot of attention to bleeding. I did to the handle tappy thing last time but I'll make sure I'm thorough. Then bed them in carefully after. If that still doesn't fix it, I'll call in help!
So I think I'll take everything apart again. Replace pads. Pay attention to alignment. Replace and bleed fluid and pay a lot of attention to bleeding. I did to the handle tappy thing last time but I'll make sure I'm thorough. Then bed them in carefully after. If that still doesn't fix it, I'll call in help!
Mr E said:
I think you may have contaminated the friction surfaces.
Clean the pads and discs with a solvent (clutch/brake cleaner) and see if that helps.
Cheers. I'll make sure to give everything a proper clean as I work through this. But would you not think this would have come out in the wash by now? The bike has probably done 200+ miles since I last did anything with the brakes. Clean the pads and discs with a solvent (clutch/brake cleaner) and see if that helps.
AI (never wrong!) reckons the brakes are these: "The Giant Talon 2 comes equipped with Tektro HDC M275 hydraulic disc brakes (sometimes listed as Tektro TKD 143). They use mineral oil and are paired with Tektro rotors—typically a 180mm rotor in the front and a 160mm rotor in the rear"
Having read a bit about this, it's perhaps worth mentioning that the handles do not feel spongey at all. They feel quite firm, it's just that they don't seem to have much effect. It basically feels like there is very little friction between pad and disc though I assume that wouldn't explain the noise so maybe that might be alignment as well?
If you've changed the pads, the squealing is likely down to contamination on the discs (this would also explain your poor performance). Unfortunately you've now ruined the new pads so you'll need to replace those too.
If the brakes are Shimano, buy Shimano pads. I messed around for far too long with aftermarket "upgraded" pads and the levers felt horrible. Back to standard and they're spot on.
New discs, new pads, another bleed, centre the caliper. If you've still got issues after that, the brakes aren't man enough for your setup.
If the brakes are Shimano, buy Shimano pads. I messed around for far too long with aftermarket "upgraded" pads and the levers felt horrible. Back to standard and they're spot on.
New discs, new pads, another bleed, centre the caliper. If you've still got issues after that, the brakes aren't man enough for your setup.
Discendo Discimus said:
If you've changed the pads, the squealing is likely down to contamination on the discs (this would also explain your poor performance). Unfortunately you've now ruined the new pads so you'll need to replace those too.
If the brakes are Shimano, buy Shimano pads. I messed around for far too long with aftermarket "upgraded" pads and the levers felt horrible. Back to standard and they're spot on.
New discs, new pads, another bleed, centre the caliper. If you've still got issues after that, the brakes aren't man enough for your setup.
Cheers. Reason for new discs? Are you thinking they might be glazed etc? If the brakes are Shimano, buy Shimano pads. I messed around for far too long with aftermarket "upgraded" pads and the levers felt horrible. Back to standard and they're spot on.
New discs, new pads, another bleed, centre the caliper. If you've still got issues after that, the brakes aren't man enough for your setup.
I had issues with the brake setup on my old hardtail that i spent ages trying to sort out - cleaning discs, new pads multiple times, aligning everything, bleeding multiple times, scuffing the discs with scotchpad. Nothing worked and they always honked like a startled goose, and in the wet the noise was unbelievable. Bad enough that it put me off riding the bike at all.
In the end i replaced the whole lot: levers, disc, calipers, pads hoses.. everything with a slightly better Shimano setup and that sorted it immediately. No idea what was wrong with the first set, but evidently it wasn't a problem with my maintenance skills.
In the end i replaced the whole lot: levers, disc, calipers, pads hoses.. everything with a slightly better Shimano setup and that sorted it immediately. No idea what was wrong with the first set, but evidently it wasn't a problem with my maintenance skills.
Without any running in brakes should work well enough to lock the wheel with minimal lever force when the bike is stationary.
Once your pads are contaminated just bin them. Disks are recoverable with cleaning.
I have no idea what happens if you use hydraulic fluid in mineral oil brakes Google suggests it destroys the seals, I'm guessing it won't be instant.
Once your pads are contaminated just bin them. Disks are recoverable with cleaning.
I have no idea what happens if you use hydraulic fluid in mineral oil brakes Google suggests it destroys the seals, I'm guessing it won't be instant.
frisbee said:
Without any running in brakes should work well enough to lock the wheel with minimal lever force when the bike is stationary.
Once your pads are contaminated just bin them. Disks are recoverable with cleaning.
I have no idea what happens if you use hydraulic fluid in mineral oil brakes Google suggests it destroys the seals, I'm guessing it won't be instant.
I’ve actually ordered discs and pads tonight. I’ve also popped the pistons out to give everything a proper clean. No intention of changing from mineral oil. Once your pads are contaminated just bin them. Disks are recoverable with cleaning.
I have no idea what happens if you use hydraulic fluid in mineral oil brakes Google suggests it destroys the seals, I'm guessing it won't be instant.
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