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forum
Shimano Disc Brake Caliper Replacement - bamboozled
Help from any Shimano experts out there would be much appreciated.
Canyon road bike came with BR-RS805 disc calipers, which are now leaking and need replacing. Nowhere has stock of these or the very similar BR-RS505 or BR-RS405.
Here was me thinking I could just swap out for any of the newer flat mount calipers but the hose size is different. Existing brakes use BH59 hose (2.3mm dia) and all the newer calipers use BH90 (2.1mm) hose, which I assume won't work with the existing levers.
What do I do? Is an adapter available or even needed to use the different hose sizes?
I'm really stuck here so any help gratefully received.
Cheers
PL
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11 comments
I've replaced a BR-RS805 caliper with a newer Ultegra caliper (R8070?) and didn't change the hose and haven't had any issues with it.
Sorry, I missed your post. Thanks for that, sounds like I'm nowe on the right track.
It only took about 10 minutes or so to swap the caliper (I'd trashed the piston on the old one) and give the system a quick bleed. I've been using it for over a year so I would have found out if there was any issue by now.
To be sure that it's all connected correctly, give the lever some good hard squeezes to make sure that the system doesn't have any weak points. I did that once and discovered that I hadn't tightened up the Shimano hose joining thingamijig enough as it suddenly separated. Much better to discover that whilst working on your bike rather than when you're trying to slow down.
Depends on your levers too. Check the Shimano compatibility chart https://productinfo.shimano.com/download/pdf/com/2.6/en
page 23 shows brake systems, hoses and caliper compatibility.
I'm assuming you have one of the three levers on the left of this chart?
So any of the calipers listed on the right will work, with the appropriate brake hose listed for the caliper under the 'BH column'.
I don't think the hose dia is an issue - the hose end fittings differ to accommodate the hose dia, their outside threaded portion matches the thread of the caliper/ lever, so that part is the same.
Hi Pilot Pete
Firstly, thank you very much for your help.
The lever is a ST-RS685. So on the basis of the above table, the BR-R8070 or BR-R7070 will work using a BH-90 cable. That right you think?
Yep, looks right to me. Your problem will be sourcing parts though I think as there is a real shortage currently....good luck.
Your current hose will probably fit the newer caliper, but the bore was changed to give better braking performance with the newer, BH90 hose. Whether you will be able to tell the difference is debatable unless you try it with the old hose then swap to the new hose.
I had a re-stock notification from Wiggle the other day on their Prime 160mm rotors, so quickly checked their site to see that they already had low stock. I put one in my basket and they'd sold out before I could buy it.