Replacement piston for Hope Disc Brake Calipers.The new hope piston is a phenolic resin which drops a few grams off the brake. This phenolic material also aids the heat dissipation of the brake.
Correct orientation for fitting: There are two letters embossed on the piston - these should face towards the pads - ie out of the caliper. This is the same as the square edged recess facing out, the angled recess facing in.
One piston only
Buy Hope Spare Dsic Brake Pistons from Chain Reaction Cycles, the world's largest online bicycle store.
Fits All X2 Series Brakes, Fits All Mono 6 Series Brakes, Fits All M4 Series Brakes - LARGE, Fits All M4 Series Brakes - SMALL, Fits All Mini Series Brakes
Rated 5 out of 5 by Brainman Macht was es soll
Der Kolben ist gut Verarbeitet, passt genau und ist sehr leicht.
03 September 2013
Rated 5 out of 5 by Anonymous Just refurbished an old M4 caliper with a pair of large pistons and a pair of small pistons, also used the M4 seal kit advised by CRC. Worth the effort a simple straight forward job and resonably cheap.
05 May 2011
Rated 4 out of 5 by Anonymous An improvement over the original piston
Fitted a pair of these a year ago and have used them on various long descents in the Pyrannees with a lot less overheating and binding than was the case with the old aluminium(?) pistons. It's a pity the the brakes weren't originally supplied with these, but better late than never. Long term wear might be an issue ...
10 April 2010
Rated 5 out of 5 by Anonymous All good
I recommend these to anyone who has old Hope's that suffered from fade and overheating. I've fitted them to both old M4's and old mini's and they make a huge difference to the heat transfered to the oil which the old aluminium one where always going to suffer from even with the steel insert (Alpine piston). This is a must upgrade for anyone with Pre-07 alu piston Hopes, esp if you're taking your bike on long descents.
08 June 2009
Rated 5 out of 5 by Anonymous Recommended upgrade
I replaced the original pistons in my MK1 minis (front 185 rear 165 disc) with these and I'm glad I did. The brakes still feel nice, firm, and smooth in operation but the squealing that has always plagued my minis has been reduced. If you've set up your brake accurately but it still squeals it's well worth giving these a go.
Removing the old pistons isn't too hard: Split the caliper and drain as much fluid as possible. Attach the presta (car) valve head of a track pump to the bleed nipple and open it a quarter turn or so. Then use a rubber washing-up glove (a thin surgical glove is too thin)to cover the small fluid transfer hole and clamp your thumb over it hard. Wrap the whole caliper half in a rag or hold it all inside a thick-ish plastic bag to contain the old piston when it ejects. Give the track pump a few strokes and the piston will fly out with a noticeable 'pop'. Undo the hose banjo from the other half of the caliper, screw in the bleed nipple, and repeat to get the other piston out. Job done!
27 January 2009
Rated 5 out of 5 by Anonymous Recommended
I bought these because the aluminium pistons were corroded and seizing in the calipers.
They cured that problem. The reduced pump up when the brakes get hot is a bonus.
16 April 2008
Rated 5 out of 5 by Anonymous Everything 'Harry' said and better. If you're stuck with an old Mini caliper (only really any good as a rear brake) you need a pair of these. The plastic piston doesn't transfer heat from the pads to the fluid so you get a solid lever feel and no pad rub. I doubt the old M4 caliper could be improved this way.
06 March 2008
Rated 5 out of 5 by Anonymous fiddly but worth it
Fantastic upgrade to older mini's - took some time getting old pistons out recommend a little clingfilm around the thread of the bleed valve to keep seal to remove old pistons.... But now no brake fade and no annoying fluid expansion with sponginess and pad rub!
19 February 2007
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