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Hi all,
I've got the setup in the title on my Salsa Fargo - Rival levers with Guide RSC 4-pot calipers. The setup works brilliantly - loads of controllable power (180mm up front, 160mm rear) - with one exception: over (a relatively short) time, the lever throw increases to the point where it is touching the bar. Last time, it went back into the shop for a bleed and came back much improved. Now it's back to the same situation - lever touches the bar at full brake.
Is this a fundamentally incompatible combination? I can't see how - surely if the lever pushed enough fluid down the line, it will activate the brake, right? I don't think there's a leak. Can anyone offer any pointers?
Ta - Adam...
How many miles are you doing on this setup / is it due to pad wear? Sometimes with guide R’s the lever travel would get longer as the pads wore - to rectify it without a bleed (or new pads) you can take the wheel out and pump the lever a few time’s to advance the pistons. Just not so much you can’t get the wheel back in.
Other than that perhaps the levers just aren’t designed to push the amount of fluid needed for the 4 pot caliper / don’t have a big enough master cylinder reservoir for that size of caliper?
I’ve got rival 1x levers that initially I kept finding that pulled to the bars after a few weeks use. Mine it was the reach adjustment winding in under vibrations. A dot of red loctite stopped them doing it. No idea if your are doing the same but worth check as it was so gradual I didn’t notice the reach change until the shift lever got stuck on the bars.
Folks - apologies for the delay in responding and thanks for your suggestions.
@joebristol - it's my commuter/tourer, so it does quite a lot. Plus, I'm living in Wellington, so it does a *lot* of hills and I am getting through brake pads quickly.
@parksie - honestly, I didn't even know there was a reach adjustment! I'll have a check.
One of the things I was hoping someone might know (or might know where to point me) are the diameters of the pistons in the Rival road calipers versus the Guide RSC calipers. I'm about to start digging through the SRAM service catalogues...
I think the rival brakes have 2x18mm pistons whilst the guides have 1x16mm and 1x14mm pistons per side of the callipers. I’m not sure how relevant that is to the amount of fluid needed to push the callipers.
I’ve had a variety of sram mtb brakes (guides / guide re / code r) and generally haven’t had any issues - but I probably do a lot less mileage on the mtbs than the road bike.
My road bike has shimano hydraulic disc brakes on it - I commute a fair amount and almost 2 years down the line I’m still on the original pads. Makes me think I need to check the fronts, but the rear caliper still has loads of meat left on the pads when I was fitting new chainrings to it on the weekend (new Cannondale Spiderings which are a thing of beauty - and I’ve just moved from semi compact to compact gearing and much prefer it).
I did some hill stuff on Monday where it was very steep coming down and I did make the brakes a bit grumbly for a while after where they got so hot!