Poor hydraulic braking

father_jack

Just changed from Avid BB7 to Shimano M615 and there doesn't seem to have the extreme braking I've heard about. It's worse than my dual pivot Campagnolo brakes.

How hard do you need to press in the levers? Literally it's like V brake (and good hard pull)

I've shortened the hoses, and burped the reservoir. They're new so don't need bleeding. The rotors are the ones supplied with Avid BB7.

The levers don't go to the bars (say on V brakes you have them fair distance from rimtherefore need a lot of travel to get braking power) they lock out about half way.

Or do I just need to keep on using them to bed in the pads?

imatfaal

With my Shimano disc brakes I can lock either wheel with one finger very easily - but that is not the benefit of good discs; what you want is the ease of modulation which allows you to not quite lock the wheels and to do this consistently and in all conditions. Not sure if this is what you mean by extreme braking. Any brake system should be able to lock the wheels - you never want to do this but you must be able to.

If you cannot lock the wheel quickly and without effort I would first off check the pads are actually where they should be and then bleed the brakes. I know you said that they don't need bleeding but it isn't much hassle and gets one problem off the list - do make sure you use correct fluid which I guess is mineral oil

father_jack

Just bled them. Will go for bike ride. Had a Boardman Comp with 160mm Avids hydraulic and seem much more power than mine.

Rear seems fine, front just seems to lack the power I was expecting.

sinisterpenguin

I have exactly the same issue BB7's are brutal, throw you over the bars braking.

Deore 615 requires a lot of pull on the lever to get strong braking. Modulation on the 615 is good but feels like there is too much travel on the brake lever to get strong braking.

Maybe in need to bleed them (again!)

The Rookie

Repetitive bleeding either means you have another issue or aren't bleeding them right the first time......

penguin_of_death

How new are they, have you bed them in?

CanAmSteve

If you shortened the hoses you introduced air into the system - or you are a magician :-)

Other issues are pad alignment to the rotors - your new calipers have new pads and may not be in perfect alignment with the rotors until the pads wear in a bit.

BB7s are good brakes when set up properly. They certainly feel different to hydraulic, but the stopping performance is not night & day (or shouldn't be).

And the dual-pivot Campys are awesome

The Rookie

CanAmSteve wrote:

If you shortened the hoses you introduced air into the system - or you are a magician :-)

Or you've read Shimano's own advice and know how to do it.....

CanAmSteve

Do tell/link. Always willing to learn, but I fail to see how disconnecting any hydraulic system does not allow the chance of air entering a system. Even one tiny bubble will be an issue

The Rookie

You squeeze the lever a few times to get the pistons out in the calliper, this gives you excess fluid to play with.

Shorten the hose, fit new olive and barb, now push the pistons back so that the hose is full, insert hose into lever.

Shimano's have a bigger reservoir than many other brands and the levers aren't flip flop so a small amount of air getting the reservoir is OK (it won't get drawn into the master cylinder), this technique works perfectly at least 9 times out of 10. If the system is overfilled just remove the top fill port and 'burp' the excess out.

http://www.epicbleedsolutions.com/blog/ ... -bleeding/

Shimano process is similar but I can never find the damn thing.

CanAmSteve

Thanks - good info. I have to replace a set of hoses completely soon so will give a variation on that a try.

The Rookie

It won't work when replacing a hose, not enough fluid in the calliper to back fill a complete hose.