Hydraulic brakes on a Bike help please

allied_assault

Well-known member
Went out on the bike today and suddenly the brake was so tight to use and the front wheel locked up.
I think that the fluid in the brake may have expanded with the heat and I know there is an easy way to let the fluid out but I have not got a clue - do I need to have this done by a bike repair shop or is it fairly easy to do this yourself - if so any advice would be greatly appreciated.
 
What kind of brakes ?
It's fairly straightforward to bleed and set up most types of hydraulic brakes but often you need specific fittings/syringes ( I'm talking from a mountain bike perspective here)
If you're stuck and you think it's a one off job getting a bike shop to do it could be the way to go. Bikescene as an example will charge 20 quid to do it. If you think it's something that'll need sorting more in the future get the kit. The procedure for your brakes will be on YouTube.
 
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Thanks guys
Done it
Just used an Allen key on the forward brake and the fluid came out
Tightened up again and good to go
Saved a bit of cash!
Well obviously you now do need to pay attention to your breaks once the heat cools off. If they get spongy then you'll need to top the fluid back up and make sure you don't have any air in the system

Hydraulic breaks are mint when they are fully functioning, but I've had a load of bother with some on my mountain bike.
 
Well obviously you now do need to pay attention to your breaks once the heat cools off. If they get spongy then you'll need to top the fluid back up and make sure you don't have any air in the system

Hydraulic breaks are mint when they are fully functioning, but I've had a load of bother with some on my mountain bike.
Cheers Tryasize
I will bear that in mind
 
If your problem was caused buy the brake fluid expanding It sounds like you didn't have a small air gap the top of your fluid reservoir. One of the jobs of this small air gap is to help compensate the fluid levels when this happens. As you can see from my working schematic above the fluid level in there changes slightly when you operate the brakes.if the fluid has expanded and taken up this space then if the fluid expands further it has nowhere to go other than to operate the brake pistons and thus cause the brakes to lock on and the lever not move
 
Has this happened before? Surely the air temperature being warm yesterday shouldn't have had that much of an effect on the fluid (which is designed to get extremely hot)? It might have been heat on one of the other parts, too much air in the system, crappy fluid or something else.

If it's been ok before, then I don't get how it could have got suddenly worse, to a point where bleeding it makes it better short term, but doesn't make it much worse long term? It's not like someone has snuck in extra fluid etc?

Did this happen on a long descent, or was it over the course of a ride?

Be careful when you next go out, make sure you test the brakes a few times before getting up to any sort of speed.
 
Thanks for this Andyw and SD
It has happened before a few months ago but they started locking yesterday on a 20 mile bike ride but was ok on Sunday
Weird
Does seem odd, I'd be getting it looked at by a pro. Brakes is one of the few things I wouldn't mess with too much.

Not sure if you're local, but the bike shop (the bike rack) at the south end of Yarm high st would be able to sort this out for you, and at least give you piece of mind. I think they only charge in 15 minute time slots too, so shouldn't cost much.

I got them to change my bottom bracket the other week, as it went stiff as hell. I had previously took off the chain and crankset etc, and was going to do it myself but I lost the bottle, and put it back together :LOL: They also sorted out my gears (which they said had been "setup" by a clown), and fitted a new chain, all for about £60 (I supplied the BB), thought that was great value, had the bike back a couple of hours after dropping off too.
 
I will see how it goes tomorrow Andy
I live between York and Selby but will probably get it looked at if I have any further issues
Thanks for the advice though to all
 
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