Why does no-one build a cable pull , hydraulic piston caliper?

In general, I really like disc brakes, and at the moment i'm looking to build up SS bike using a TT-base bar on an MTB frame and mtb disc wheelset. ( Quirky, but hey, aint that what SS is about??? )

Whilst it would be simple to use mechanical calipers and TT levers, the thing which cheeses me off from experience is the static inner pad on mech discs. Hydraulics and their opposing pistons just seem so much better in terms of clearance and grabbing the disc without twisting the rotor.

So instead of having a master cylinder in the lever and a slave chamber in the caliper pushing the pistons, why not have a cable pull lever on the caliper itself acting on a chamber ( like the current hydraulic levers do ) which then pushes directly onto the pistons. Would be simple to bleed effectively a single chamber. Would simplify the hydraulic side of things ( if making the calipers slightly bigger ) and you could get super light levers.

Personally, I think there is a market for it. The ability to use any cable lever ( TT, Road STI, V brake etc ) , but with the benefits of hydraulic caliper pistons.

Or is that fairy land dreaming ???

Well, Rockshox made one where the master cylinder was at the calliper in the late (ish) 90's IIRC. It was, by all accounts, crap (although in fairness I personally have never tried one).

Hope made a master cylinder that was actuated by a road brake cable, gives plenty of power on my parent's tandem with some sort of four pot brake, but they only made it for about a year, so I guess there wasn't a huge gap in the market. When my parents got their tandem Hope had to be asked nicely to make a 2-off of them… 🙂

The other issue I've heard of as far as road bikes goes is that the road muck and salt makes the callipers more likely to seize, which isn't an issue on fully cable actuated brakes. I agree that the one pad only moving is a bit rubbish, but probably the best solution for disks on an all weather road bike. Hub brakes are probably best if you're away from big hills that will make them overheat! More suitable and less blingy for the pub bike too…

look up amp cable disc or pro stop they were both cable operated hydraulic discs…the caliper floated from side to dide but iirc only one piston moved

they died out at least 10 years ago if not longer

There is, or was, a Swiss company that modified Hope cylinders by attaching them to a bracket that fitted below the stem in place of a spacer, and the cable pulled on the linkage where the brake lever would have been. Very neat, but not cheap, it allowed the use of a Mini on a road bike with any make of lever. I may still have the original 'site book
marked, I'll have a shufti in a mo' see if I can find it.

Because using a TT bar with discs is a very, very niche set up and so no one would buy them?

A bit of googling and use of the wayback machine throws up this from 2002:

This looks a bit more recent:
More on the bottom two rows HERE
http://www.sticha.ch

Oggles, that's exactly what I was looking for, but I didn't have it bookmarked. Thank you.

This looks like a good solution for splitting a bike in half for transport.

they would work very well with a bike with those couplers on. Alternatively just use bb7 road as they really are a good brake and cheap 🙂

Wow, I was thinking I would phone Hope and suggest this exact thing to them. Now I can just beg for one of those instead 🙂

you could just use a floating disc in a full cable set up. A cable actuated hydraulic caliper set up is surely going to be quite expensive given the numbers of them likely to be made. i don't think it simplifies the design much at all.

This looks like a good solution for splitting a bike in half for transport.

I can't see that myself, it would surly be easier to just detach the caliper (2 bolts) then cable tie the looped up brake to the handle bar, no – readjustment or kinked cables.

i think that this cable actuated hyraulics is probably best for a heavily laiden touring tandem with drop bars, i can't see much use for it otherwise, commuting bikes is out of the question, as hope calipers are allergic to the road grime you get in the city.

As above it's been done/tried and it's not great.

Main problems:

– you have the disadvantages of cables (drag) with the disadvantages of hydraulic (having to bleed – ok only occasionally).
– They're not super light – in effect, the caliper is a combined caliper and brake lever (since the cable has to operate the a piston to make the caliper brake pistons move) with more weight than a simple caliper
– There's sweet FA market for it – while there'd undoubted be a few people who'd want a similar setup, it's a very small market in relation to people who ride normal setups so who's really going to bother unless it's to solve a 'problem' like th travel solution above (and as per shoefiti, I reckon just unbolting the caliper is a lot better).

Oh and SS isn't about being quirky – it's about riding a bike with one gear for whatever reason you have for that. Not everyone rides a SS to try and be different/Krazy/Mad…

the thing which cheeses me off from experience is the static inner pad on mech discs. Hydraulics and their opposing pistons just seem so much better in terms of clearance and grabbing the disc without twisting the rotor

There's the problem with the question – it's just a non-issue. The only reason I can see is the lower maintenance, but is seems the market is not there

BB7s are really good and, although I see your point about bending the rotor beiong a funny design, they work well and are very reliable. I also think they are one of the only disc brakes rated for tandem use so they are obviously doing something right!

If you really want to use hydros then I think the easier solution would be to use the hydro lever mounted on the end of the bullhorn with the lever facing back towards the bike, so it looks like a bar end lever. Might look a bit funky (but its craaaazy SS so that's ok) and you might need to file the inside of the lever to make it fit, but it will be a hell of a lot simpler than a cable to hydro set up.

TBH it'd be pretty damn simple to make a two-opposing piston mechanical brake, just a little bit heavier.

I just called Hope re the steerer-mounted dealy. They don't do them any more…

But, their Swiss distributer/contact/whatever does. See here. Not cheap at about £400, but if it's what you want… 🙂

I reckon you could modify some standard levers to do a similar job mounted on the bars (you'd need to enlarge the clamp diameter, which would be tricky).

TBH it'd be pretty damn simple to make a two-opposing piston mechanical brake, just a little bit heavier.

Yep, RST did it back in 99/00-ish.

The problem with cable actuated hydraulics is that they overheat readily.

The question of wanting discs using road levers is a much more relevant one. BB7 roads work great in most conditions except those which cause rapid pad wear. In such cases you need to stop many times on a ride to wind the pad adjuster in. I would love to see a hydraulic lever to fit road diameter bars – I know people (the king of sweden) who've done it by modifying mountain levers but it's not easy. Magura also made a road lever to match their hydraulic rim brakes but they're very rare.

Oh, and fisha, for your purposes I think you would be best off just using Avid BB7 road calipers.

Because you are massively over engineering what is a comparatively simple idea and loosing a massive amount of power in the process.

The loss of power involved in making the pull of a cable operate a master cylinder would be huge.

The idea of hydraulics is that you turn a large movement at low pressure into a small movement at hight pressure. You would need a cam or pully type system in a cable operated lever to move the amount of cable required to produce the same braking force of a simple hydraulic lever.

It might work on a bicycle where disks have always been a bit of overkill when someone is pedalling down the road, but I wouldn't fancy having that system on a Honda Fireblade!!!

Hey Sam am collecting up some bits for you dont worry J 😀

<waves>

I've got a set of the orig Hayes HMX-1 hydro mechanical jobbies from the early 90's where the master cylinder and calipers are in one casting at the disc. Was using them day-in/day-out until very recently, but all the seals now need replacing and I'm bu%%ered if I can find them anywhere. As a bit of retro history, I'm not going to throw them out…. and when they work they're fine, but no better than the mechanical discs that replace them.

Sam, I have a Magura drop-bar lever waiting to go on a Grypon, but they don't have V bosses 🙁

And no, you can't have it.

Because you are massively over engineering what is a comparatively simple idea and loosing a massive amount of power in the process.

The loss of power involved in making the pull of a cable operate a master cylinder would be huge.

The idea of hydraulics is that you turn a large movement at low pressure into a small movement at hight pressure. You would need a cam or pully type system in a cable operated lever to move the amount of cable required to produce the same braking force of a simple hydraulic lever.

Wot he said. You lose any advantage of hydraulics by making them cable activated.

Sam – Member

The problem with cable actuated hydraulics is that they overheat readily.

Yep, anyone remember Hope C2 closed hydraulic system? Overheating on long DHs to the point where the wheel locks. Caliper only would have far less fluid to take up the heat

I have one of these:

in the garage. It used to drive a Hope C2 on the back of our tandem, from a V brake lever. If anyone wants it – a tenner posted? It attaches to a cable stop.

I just don't see the advantage over just having cable operated discs.

What problem is having the final stage hydraulic going to solve?

apart from not being very pretty, whats wrong with having a mtb set up and bending the lever to fit the bars? Can't see a problem, bending levers is easy enough with care. Hmmmm I wonder.

boxelder, ill take it please, be perfect for a little cx project :0)

whats wrong with having a mtb set up and bending the lever to fit the bars? Can't see a problem, bending levers is easy enough with care. Hmmmm I wonder.

The clamp diameter is different, that's the hard part. Though bending levers is not really a great idea either, that's one thing you don't want snapping unexpectedly… Also you don't have any 'hoods' position. Would just be nice id someone would make a proper drop bar hydraulic lever…

It is just a pity you cant get a larger clamp diameter, or more to the point, that roadie bars and mtb bars aren't the same diameter.

I was just thinking out loud … I'll not be losing any sleep over it there not being such a caliper. I do remember seeing the Hope doodah … that looks cool I must admit.

As for SS being quirky …. 😯 …. I knew some would bite.

because;

-on road bikes you dont need the braking power or weight

-on CX bikes disk brakes are banned

-off road where you could feasibly want the braking power why would you want drops (unless your John Tommac)

-they boil as soon as you use them

-cable disks work just as well (badly IMO) and once the pad's are bedded in only need adjusting once in a while (as theyr so bad you will never use them)

So that leaves the uber-niche off-road, drop bar, collapsible tandem?

because;

-on road bikes you dont need the braking power

I bet you don't use them, correct? You don't need the power on mtbs either…

cable disks work just as well (badly IMO) and once the pad's are bedded in only need adjusting once in a while (as theyr so bad you will never use them)

you dont half talk shite

You don't need the power on mtbs either…

Correct. Which is why Vs are fine if you don't ride through mud.

The uber-niche off-road, drop bar, collapsible tandem

😀

-on road bikes you dont need the braking power or weight

doesn't harm, though, and they keep rims in good shape.

good enough for him

-they boil as soon as you use them

wrong again, why would they?

-cable disks work just as well (badly IMO) and once the pad's are bedded in only need adjusting once in a while (as theyr so bad you will never use them)(sic)

contradicting yourself there; are you drunk?

You could feasibly use more braking power on the road than off – as you get better grip on tarmac than on gravel. assuming you don't have stupid skinny tyres of course