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Last weekend I changed some pads on my wife's car. Easy peasy - one piston to retract and that can be done with a great big g-clamp from the side. Put it all back together - instantly re-centred, minimal drag.
This weekend, I have lost my riding time to buggering about with sticking pistons on one side of a set of Hope Minis. And my bike with Avids is out of action waiting for me to do a caliper rebuild for the same reason!
So, why does nobody make single piston bike brakes?
If I had to guess it would be something to do with either power (I don't really understand the physics of single vs dual pistons), drag or rattling of the floating caliper - although the latter isn't an issue in the car.
Any mechanically minded people out there care to explain?
hayes 'sole'...
Hope cable operated.
BITD
Ah......were they any good? The Sole was at the bottom end of the market, wasn't it?
I remember the days pre-Japanese cars when all cars had pistons both sides of the disc. Then came the cost cutting.
Decent cars still get proper calipers mind!
You want the cost cutting to extend to bikes too?
Main reason on a bike is durability. The crap we ride through would soon f#ck up any sliding mechanism. Despite the problems the opposed-piston type we all have are much more durable.
Opposed piston are much better - sliding pistons give you something else to wear out and stick.
The hayes sole wasnt a sliding caliper, one pad had a moving piston, the other had to be manually wound out as the pad wore.
Thats why they were low end.
These bad boys are floating caliper. Very heavy. Very expensive. Very powerful.
http://www.ukbikestore.co.uk/product/13/gustav_pm6_2011/magura-gustav-m-2011-brake.html
Floating calliper? Don't those need special linkage contraptions that channels braking force away from single pivot suspension setups, you used to see them on old Santa Cruz Super 8's and Konas.
That is a floating brake...
If you want to know why 'floating/sliding' calipers aren't so popular, try running an early Japanese motorbike - when they decided that they didn't want to pay royalties to Lockheed (if memory serves me well) anymore..., they were crap.
The only reason your car ones work is they are overbuilt and have great forces going thru them - but they do seize.
My original Hope mechanical disc (circ 1995) used a floating caliper. Regularly got jammed up with Peak District grinding paste mud. Had some super tight tolerance sliders machined to see if that stopped the crap getting in. It did, but they then wouldn't slide!
And following br's post, my beloved Mazda 323f has floating front calipers, and the sliders seize every 6 months and need stripping and regreasing.
Give me dual pistons anytime please!
BR is right - Lockheed wrapped up the patents for opposed piston brakes so sliding calipers were devised to get around this. Hence they were used on early jap motorbikes - always caused no end of issues
There are also some incredibly nasty cable operated ones doing the rounds on supermarket specials, so much slop in everything that we turn them away rather than putting our name on a repair that's obviously not going to work.
Someone's mentioned Magura Gustavs I assume?
I was thinking about this today as a potential method of solving the new fangled road hydraulic disc brakes and the use of neutral service cars. Could it be a solution to the inevitable alignment issues?
Had these on my old RD400E. Kept sticking I seem to remember.
Had a flashback to the fun times on that bike cheers 🙂
[i]Had these on my old RD400E. Kept sticking I seem to remember.
Had a flashback to the fun times on that bike cheers [/i]
Yep, RD250E on L plates here 🙂
monkeyp - MemberI was thinking about this today as a potential method of solving the new fangled road hydraulic disc brakes and the use of neutral service cars. Could it be a solution to the inevitable alignment issues?
For professional racing maybe, but a floating system would end up heavier than 2 pistons to work properly so I doubt it would sell well to civvies. For professional racing, is there enough leeway in the minimum weight rule to allow for this? Ie we know that they could build team bikes lighter if they were allowed to race them: could they lose weight on the rest of the bike to allow for a heavier but more adaptable floting caliper brake.
Ultimately I expect that a [i]very[/i] fine/accurate agreed standard for hub and rotor dimensions will be the way forward though.