Can HY/RD disc brakes be upgraded to hydraulic?

outfox

Does anyone know if cable actuated hydraulic disc brakes (such as TRP HY/RD) on a road bike can be upgraded to full hydraulic? It would mean upgrading the shifters and replacing the cable line with a fluid line, which should be straightforward I would hope. But the brake housing would need to be replaced too, to a model which does not have a reservoir in the housing. The question is, do all brake housings have standard attachment points for the frames, regardless of whether the housing includes a reservoir or not? Or are there different frame designs, specific only to HY/RD or to full hydro? If they are standard, then it should be a simple matter to swap out the cable actuated housing for a full hydraulic?
Sorry if this is confusing.

rab!dmonkey

Short answer: no.
Long answer: no. HY/RDs take a cable, end of. Hydraulic brakes come complete as an assembled lever-hose-calliper. The reservoir is in the lever body (as opposed to the calliper with HY/RD). If you have fully-housed brake cables (pretty much all disc-compatible bikes do), then the hose is a straight swap for the brake housing. Otherwise you'll need to get some little doo-dahs that allow you to mount the hose to your cable stops.

outfox

Thanks Rab!monkey. If I understand correctly:

1. Levers: Need to purchase new levers which include oil reservoir.
2. Hoses: Bike in question has fully housed brake cables, so should be possible to swap cable lines for hoses.

What about the calliper unit? Can I simply unbolt the cable-actuated unit, and replace it with a fully hydraulic calliper unit? I'm a noob on this, and I don't know if all disc brake bikes have standard mountings to that they can take any kind of calliper unit (whether cable-actuated or full hydraulic).
Thanks for your help.

Alek

Theoretically it may be possible - there is a bleeding port on the caliper, which could be modified to accept a hose.

I would't bother though - for the price of Hy/RD sold secondhand you can get a really good quality hydraulic MTB caliper.

You would still need a hydraulic road shifter, which are quite expensive at this stage.

Take a look at Shimano 105 5800 hydro levers + calipers.

outfox

Alek wrote: »

I would't bother though - for the price of Hy/RD sold secondhand you can get a really good quality hydraulic MTB caliper.

Thanks Alek. Do you reckon such a caliper would fit a road bike? Are all the mounting points standard across all frames and all caliper units?

Lumen

You're basically talking about replacing your entire braking system, plus levers.

There are two standards for caliper mounting: post mount and IS.

http://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1638-51mm-international-standard-74mm-post-mount

But you're going to need new calipers anyway, so just get ones that fit your frame & forks.

Alek

I am not 100% sure about the modulation (MTB calipers may deliver more power quicker, which can result in an endo on road slicks) but the mounting hardware is the same - either post mount or IS.

outfox

Thanks guys. My worry was that if I decided in the future to replace the cable-actuated disc brakes with full hydraulic, I'd suddenly discover that the frame design would not allow any other type of caliper to be fitted, other than the cable-actuated type already on it.

Pigeon Reaper

you could go for something like these too.
http://www.wiggle.co.uk/trp-hy-rd-cable-actuated-hydraulic-disc-brake-caliper/

outfox

Pigeon Reaper wrote: »

you could go for something like these too.

That's what's already on the bike I'm looking at. Hydraulic caliper, but cable from shifter to caliper.
I reckon that cable-actuated is just a transitional thing, and in a few years full hydro will be the norm for disc brakes. I'd like to upgrade at that stage.

Pigeon Reaper

Now it makes more sense. It would be easier to just upgrade the calipers and brakes in one sealed system than try to keep the current calipers. Let us know how you get on with the cable actuated hydralics.

rab!dmonkey

outfox wrote: »

Thanks Rab!monkey. If I understand correctly:

1. Levers: Need to purchase new levers which include oil reservoir.
2. Hoses: Bike in question has fully housed brake cables, so should be possible to swap cable lines for hoses.

What about the calliper unit? Can I simply unbolt the cable-actuated unit, and replace it with a fully hydraulic calliper unit? I'm a noob on this, and I don't know if all disc brake bikes have standard mountings to that they can take any kind of calliper unit (whether cable-actuated or full hydraulic).
Thanks for your help.

Levers: yes, you need new hydro ones. They will come assembled with the hose and calliper. Think of it as buying complete brake system with additional shifty bits.
Hoses: yes, you'll just zip tie the hoses in to the same place your cable outers go.
Calliper: yes, just unbolt the HY/RD and put the hydro calliper in its place.

Lumen wrote: »

You're basically talking about replacing your entire braking system, plus levers.

There are two standards for caliper mounting: post mount and IS.

http://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1638-51mm-international-standard-74mm-post-mount

But you're going to need new calipers anyway, so just get ones that fit your frame & forks.

No one has produced IS-mount callipers in about ten years and I've never seen one intended for a road bike. Post-mount callipers have been universal for some time (though that's coming to an end with Shimano's nascent 'flat-mount' standard) - they are used with IS frames and forks by way of adaptors, the same way you adapt for a different size rotor. The disadvantages of IS posited in that article are moot because you have to use an adaptor with any relevant calliper.

Lumen

rab!dmonkey wrote: »

No one has produced IS-mount callipers in about ten years and I've never seen one intended for a road bike. Post-mount callipers have been universal for some time (though that's coming to an end with Shimano's nascent 'flat-mount' standard) - they are used with IS frames and forks by way of adaptors, the same way you adapt for a different size rotor. The disadvantages of IS posited in that article are moot because you have to use an adaptor with any relevant calliper.

Ah. I'm fairly sure I've read about different standards of mounting on the new crop of disc braked road bikes; maybe I was getting confused between post mount and flat mount.

JBokeh

Alek wrote: »

I am not 100% sure about the modulation (MTB calipers may deliver more power quicker, which can result in an endo on road slicks) but the mounting hardware is the same - either post mount or IS.

It gets a bit complicated if you mix and match levers and callipers,the lever might not displace enough fluid causing the lever to go down to the bar and you'll not get brakes,or else it could displace too much,and it will lock up the brakes if you look at them. Though you should be safe enough doing it within the shimano brand with callipers and levers from a similar range.

Think the whole point of the HY RD brakes is that you can keep your existing cable levers,and still have the advantages of the hydraulic brake performance/feel. It might be possible to do a really dirty trick like connecting a brake hose to the bleed port with a Y shaped fitting,one end going to the lever,and one end to a bleed nipple,and letting the existing master cylinder in the calliper do nothing. The fitting won't be the type of thing that you would get in a bike shop,i'm not sure if such a thing even exists,but i'm sure a company that specialises in hydraulic hoses can help you.