itboffin
Guru
- Location
- Marlborough, Windshire
doesnt it just beed bleeding? even my mechanical STI disc brakes engage like your first pic
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A Minging Manc...
- Location
- Sunny Ashton-under-Lyne
That's not right. I suspect better bleeding required.
I have Di2 on one bike and RS-805 on another, I cannot pull to the bars on either. For sure, the biting point is not as keen as on my Shimano equipped MTB, but yours does not right. If you pump them a few times do they firm up?
Looks like they need bleeding again. I've had RS785's and currently have R8070's on one bike and R9170's on another - It can be a pig to get them bled right but once they're good theyre very good. When I first fitted the R9170's it took 3 or 4 bleeds before I got them to bite at a reasonable point in the travel.
Some images for reference - First R8070's
Then R9170's
Finally the SRAM Rival 22 hydro's on my commuter for reference:
All pretty similar, my R785's were in the same ballpark. Whether that's where you want them to be I can't tell, but they feel fine to me. I run the Hope V4's on my full suspension mountain bike with very slack levers, coming back almost to the bar. The E4's on my XC hardtail however I have set up to bite after a very short lever travel. Horses for courses
Some images for reference - First R8070's
Then R9170's
Finally the SRAM Rival 22 hydro's on my commuter for reference:
All pretty similar, my R785's were in the same ballpark. Whether that's where you want them to be I can't tell, but they feel fine to me. I run the Hope V4's on my full suspension mountain bike with very slack levers, coming back almost to the bar. The E4's on my XC hardtail however I have set up to bite after a very short lever travel. Horses for courses
No difference with pumping.I've tried strapping the levers over night and that makes no difference either.
They've now been bled at least half a dozen times.I've bled them again since the LBS had a go and they're the same.
I think I'm going to start again.New hoses/barbs/olives and fluid.It's a long shot but you never know.
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A Minging Manc...
- Location
- Sunny Ashton-under-Lyne
Waste of time and money. You might strike lucky and get them to bleed that way but it will be nothing to do with the new parts. How are you bleeding them, top to bottom or bottom up? I had an mtb brake that gave me a bit of trouble about a year ago after replacing a damaged hose. Bled it multiple times but results were an inconsistent bite point that also seemed to vary during usage. I became convinced that somehow air was getting in & out of the system at the master cylinder (hence the inconsistency) so decided the solution would be to reverse bleed via the caliper nipple and force any air at the lever out via the reservoir.
In the end I made one desperate final attempt to bleed them the 'normal' way of topping up at the reservoir and pumping out through the nipple but before first opening the nipple I pumped the lever several times till it was locked rock hard and when cracking the nipple I was rewarded with a satisfying POP as a final bubble of air was expelled from the caliper.
Turned out there must have been a stubborn air pocket lurking in the caliper and the changes in volume with temperature was giving an inconsistent bite point. Once that was sorted it was back to 1st class business as usual.
This was shimano XT M785s and the calipers are near identical to the R785s (I have both). Maybe these are prone to holding an air bubble in the caliper?
I’ve bled them from the bottom up and then filled the little gizmo
that screws into the lever and just let fluid run through.Done this a couple of times. Trying new hoses etc is a lot cheaper than any other option.
If that doesn’t work then my Di2 adventure will be very short lived!
that screws into the lever and just let fluid run through.Done this a couple of times. Trying new hoses etc is a lot cheaper than any other option.
If that doesn’t work then my Di2 adventure will be very short lived!
I always fill bottom up with a syringe in the caliper bleed point on shimano road systems, but I use Hope RX4 calipers. Once I've got it filled I pump the pistons out and push them back in a few times then lock the lever against the bars and put a really good vacuum on the caliper by pulling the syringe plunger until the bubbles stop then pushing fluid back in. Once I've done this a few times and can't get any more bubbles to appear I make sure the reservoir at the top is full by pushing fluid up from the syringe until it almost overflows (I never put fluid in at the top), then put the reservoir cap back on. Then make sure pistons are all back in and take the syringe off the caliper and reinstall the bleed screw. I don't know what the 'correct' procedure is, but this is what I've developed over the last few years and seems to work for me 😊
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A Minging Manc...
- Location
- Sunny Ashton-under-Lyne
Have you tried pumping them and then opening the nipple? This might shift that last bubble of air that is causing the bite point issue.
I do similar although I also suck fluid back down sometimes to try and clear a bubble.
I’m going to try that. Thats how Car,motorbike and Hope brakes are bled.
If only Hope made Di2 compatible Brakes/STIs
You can use hope calipers with Shimano levers...I’m going to try that. Thats how Car,motorbike and Hope brakes are bled.
If only Hope made Di2 compatible Brakes/STIs
I like Skol
A Minging Manc...
- Location
- Sunny Ashton-under-Lyne
I bleed my flat bar Shimano hydraulic brakes from the top using a syringe body as a reservoir and pumping through one squeeze at a time, just like car brakes. Only had any issues the once and have never had to bleed the road bike brakes yet.
It looks like my build is not quite finishedHope RX4-sh calipers, thats what i have on my two Di2 road bikes
