There’s a Shimano document that gives you step by step pictures and details of how to shorten a Shimano disc brake hose without the need to re-bleed the brake. It says as the last step, “push the pads back into place with a tyre lever- any air will be then be forced into the reservoir.” Has anyone done this? I can’t understand how any air forced the reservoir won’t be a bad thing?

I’ve cut hose and just taken lever reservoir cover off and pumped lever a few times. Worked fine didn’t need full bleed.

Done it with 4 brakes! No problems!

Followed the instructions on the ‘cheap brakes from Rose bikes’ topic!

You’re very perceptive ciderinsport. That’s exactly why I’m asking. I’ll look at that topic. Thanks both of you.

If you force the air into the reservoir when the cap is off, then it’d be OK I guess.

Air in the reservoir doesn’t really matter unless you use the brake upside down – the reservoir is closed off from the rest of the system when you pull the lever, and the hole is at the bottom.

I don’t know about the new ones but with previous years’ brakes I think air in the reservoir is sort of inevitable as presumably some will get trapped in when you put the cover back on…

Thanks, I feel more confident about trying it now. Ciderinsport….Is that topic still out there? I wanted to see if it’s the same as the techdoc I have? (take pads out, work pistons out a little, cut, fit olive and insert, reconnect, press back pistons with lever higher than caliper?)

I swapped the levers round and shortened cables for a mates Yeti with no bleeding required, dont recall pushing pistons out though, just googled it from memory

I’ve done it on a few sets of shimano brakes.

Pads out, pull levers to move pistons in. Dismantle, cut, re attach push pistons in top up reservoir, ride. Make sure you have the reservoir on the bar and horizontal so the fluid doesn’t spill but you can leave the cap off to top up. Worth rigging something up to hold the hose higher than everything else as you may need free hands etc. I used a clothes peg and electrical tape on my bar.

Tbh, you don’t really need to worry about pushing the pistons etc..
I just left everything as it was, cut the hose, refitted olive and the other bit, then reattached hose. Gave the hose a tap a bit to let any air rise, and didn’t pull the lever for about half an hour…sharp as you like, easy!

DrP

done it a few times when shortening hoses and I push the pads out to burp the lines and make sure no air trapped. Always worked fine. The air will sit at the top of the fluid in the reservoir against the diaphragm.

I bought the XT Rose Bike deal and did the hose swap over, shortening the rear brake hose at the same time. Unfortunately, it didn’t quite work for me. The front brake is superb, the rear is good, but just not as sharp as the front. There’s no leakage from the new olive, so I guess I’ve left an air bubble in there when shortening the hose. However, the brakes are so good that I didn’t really have any issues with them in the Pyrenees a few weeks ago, just a bit niggling that I know they’re not 100%. There are two methods being recommended on that thread, I didn’t follow the one where it was recommended to push the pistons out, I did the same as DrP^.

I didn’t take the pads out, just cut hose and reattached using new olive. My mechanic friend told me to put rubber bands around the grips and brake levers to let any air rise up to the reservoir overnight. I just topped them up afterwards and they’ve worked fine ever since.