I have a technical question I’m hoping someone can help me with. I have a road bike that has been running shimano rs505 hydraulic shifters and calipers for the past 3 years. I decided to upgrade to new 105 R7020 shifters assuming they would work fine with my calipers. After getting everything set up, and bled, I am finding that I am still able to to pull the lever all the way to the bar and barely getting enough pad movement to touch the rotor. I should note that I did not change the hoses out for the BH90 set that came with the shifters, I only just found out that they were different from the original BH59 hoses.
I looked up the shimano compatibility chart and it does not show these calipers and levers as compatible, however the internet seems to have mixed responses on whether these should work. Some say that all shimano levers and calipers should be compatible, but from what I’m seeing it doesn’t seem like the lever is moving enough fluid for the calipers.
Is there any way to make this combo work? will changing the hose make any difference? Am I missing something else with the setup? Thanks,
Everything should be compatiblish. The difference is that one is a 2.1mm bore vs 2.3mm bore and use a different need. The surround hardware is the same.
That’s a 10% flow rate difference in the hose (the needle really controls the flow). You would notice a “speed of brake application” difference if it mattered or a leak if you did it wrong. You have a bad brake bleed.
The sh90 is the more rigid hose with faster activation. The SH59 is a more flexible hose, but will be more progressive. It’s really a feel difference. You might want to use the SH59 in the rear anyway.
- Rattle the brake lines around a bit/bounce bike, wait an hour, repeat
- Repeat bleed procedure…
- get all the air out of your fluid in the syringe (2/3 full), maybe do a bit of vacuum on the caliper to start out, shake the lines again, wait…
- Normalize the lower pressure at the caliper, remove the top bleed port, put on funnel, add a bit of fluid to the top - 1/4 full.
- Push your lower syringe most of the way in, without emptying it or pushing bubbles or overflowing top. Rattle lines. Let air bubbles come out of top.
- Pull a good bit of fluid back into the bottom.
- Now squeeze the lever, hold, push the bottom syringe, release brake lever. Repeat.
- close off bottom syringe (bleed screw or pincher) and check lever feel. The bleed block in the caliper should let you know if things are feeling right.
- If it’s good, close the bottom port and remove the top. If it’s bad, repeat.
agree with jfranci3.
Did you use the correct barb, BTW? The barbs are different due to the different bore size. You probably don’t need to change it unless you cut the hose. If not, use the correct barb. Use new olives whenever you crack it open to change/manipulate hoses, since it’s a compression fitting. It will deform when compressed, so I hope you changed the olive to a new one.
It sounds like you need a bleed, as jfranci3 pointed out. Once you’re sure the hydraulic line is airtight, then the bleed should hold.
Thanks for both of your feedback, I dont think I used the correct barb. I pushed the one for the BH90 hose into the existing one and now that I understand they are different diameter I imagine that might not be providing a proper seal. I think I will go ahead and run the new hoses with new barbs and olives and try to give it a good bleed again.
You’d have a leak if the wrong barb. Is the caliper leaking out of the piston/pad area? Did you cross thread the bleed screw?
It’s really really easy to screw up a fresh bleed. You might have just had the bike sitting at the wrong angle. You can just put a bunch of fluid up top and let it run through.
About 6 months ago I:
- took my bike off the trainer
- placed the bike upside down on the floor
- stepped over to handlebars to grab a wheel
- and broke a shift lever!
My doctor is pretty sure I fractured my middle toe:
Kung Fu Panda good times!
Anyways, bike came with BR-RS785 brakes and ST-RS685 shift/brake levers. Got a deal on ST-R7020 and according to the compatibility chart:
Source: 2020-2021 SHIMANO Product Information Web
I only replaced:
- the shift/brake levers with new ST-R7020 105 series
- the BH59 brake hoses with BH90
Believe my LBS used the old barbs.
Okay so the local bike shop replaced the brake hoses and bled the system, and… I could pull the lever all the way to the bar. So they bled it again, and… better but clearly wasn’t giving me confidence. So I was pretty unhappy.
At the same time I needed bearings replaced in a DT-Swiss rear hub and I asked the LBS if they wanted to try. That wasn’t going particular well, so my buddy said “go to that bike shop across town, they have an ex-pro tour mechanic.”
Long story short, I forgot to tell the ex-pro mechanic about the squishy brakes but he noticed it on the post bearing replacement test ride. And he fixed it. And forget to tell me he fixed it. But he obviously fixed it because the brakes were back to normal.
Hope that helps.
I havent seen any leaking, I only replaced the barb on the lever end. I imagine I havent been able to put enough pressure in the line to really cause a leak, but its possible there is some leaking slowly, I will check when I get home. I dont believe I cross threaded anything.
Thanks for your experience with a similar situation. I just ran over to my LBS and spoke to a mechanic for about 10 minutes and he seemed to think that it might kind of work but probably not very well because the RS505 caliper is designed for the BH59 hose. This sort of matches up with the chart because it doesnt show any applications of the RS505 with the BH90 hose. I am enouraged to see that the RS505 shifter does work with the R7070 caliper when the BH90 is used, and therefore these two systems should have the right cylinder ratios.
I think at this point I will go home and do as has been suggested and swap hoses and use the correct barbs , do a good bleed and see how it works. I do already have one 105 caliper on order but I think I will need to use an Ultegra front because I cant find another 105 anywhere. Obviously this is undesirable because you know…matchy matchy.
Thanks again for everyone’s input, I will report back with how things work out.
I was thankful my 2015 bike came with RS785 brake calipers and it was listed as compatible with the new 7020 shift/brake levers. But then it didn’t work well after LBS installed and tried tuning twice, so I was thinking maybe the combo had reduced braking power. Was very happy after the ex-pro mechanic worked on the bike.
I’ve got two 105 calipers that came with the two kits, they are flat mount and my bike is post mount.
FWIW, even the compatible rs785 calipers and rs685 levers with BH59 hoses have a lot of squish and you can almost pull the lever to the bar if set up with the minimum reach. Swapping those to BH90 feels infinitely better. The original thinking was that they wanted to mimic the feel of caliper brakes so people wouldn’t endo but they pretty quickly decided people didn’t actually like that. I swapped to BH90 for all my disk brake bikes and they are way better. You can even use the 2 piston XTR calipers as piston area is the same between road and mountain for most of the lineup.
Interesting. My 2015 Domane came with that exact gear and from the beginning there was zero squish. So I thought it was normal to be able to do an endo if the front lever was pulled hard. They only got squishy when the pads needed to be replaced, or perhaps before the annual bleeding.
Yea its kinda subtle until you make the swap. If you ride a bike with R7/8/9000 levers and RS685 levers back to back its pretty clear, you can search the interwebs and find lots of discussions on the topic
So update… just got off the phone with Shimano Canada…
Apparently with the Ultegra and Dura Ace new Hydro Di2 shifters, no changes are required at all… you just take the BH90 cable and use the BH90 insert and banjo that are supplied and thats it…
He told me the BH59 hose was used before because they were worried about the modulation of the brake and the wider hose gave the brake more of a road brake feel…
Also, mineral oil doesn’t absorb water like DOT brake fluid sram uses so yearly bleeds probably aren’t necessary on the road. I’ll go through dozens of pad sets before I bleed.
In that same thread someone said the stock BH59 hose inner diameter is slightly larger than the BH90 hose, and therefore upgrading the hose may result in less force/push on the RS785 post mounted brakes. Indeed, switching from RS685 levers to the new R7xxx levers and upgrading to the narrower hose line resulted in more squishy brake action. The stock brakes felt stiffer/tighter.
I’ve been at the LBS during annual brake bleeds and there has always been water in the lines. I’ve had the lines drained and refilled without new pads and it improved braking but maybe the brakes needed adjusting Road riding about 5000 miles/year and outside all months in the year, in variable temps but always in 32F - 102F range.
My new bike’s SRAM brakes seem ‘better’ (less noise and great stopping power) than the Shimano on the Domane.
This results in a firmer pull, not squishier since the master cylinder size remains unchanged. Smaller hose diameter results in more fluid being moved for the same lever pull distance. Slight differences in lever pivots etc but in general this is true.
Interesting you are getting water in the lines, my year round commuter never has any water in it, just some dirt contamination whenever I bleed, the only way for water to make it in is past the caliper pistons, but I also run full fenders during the rainy PNW season. My cross bike with Sram Red calipers gets bled annually and those do get some water.
If I can add my thoughts on this, It seems to me like this is a misunderstanding I keep hearing. It seems like the hose diameter shouldn’t have any impact on the braking power. All it does is reduce the volume of fluid in the lines. The cylinder will push the same volume of fluid regardless of the hose diameter, the fluid just needs to flow farther/faster through the hose. I am guessing the thinner ID is a result of a stiffer housing, and this is how better feel and less squish is achieved.
Yes, it in a perfect system there would be no compression of fluid and no expansion of brake hose, but even on the same bike the front and rear brakes will feel slightly different due to the increased hose length. The more fluid volume and hose length the more squish
after posting earlier I read the entire thread and the last post was best:
which IMHO explains why my LBS delivered squishy braking and the ex-pro mechanic was able to dial it in.
Haha yea, the free stroke adjustment on the RS785 levers also didn’t appear to do anything which was a common complaint. Works well on the newer gens
Just wanted to follow up on this for those interested. I ran the new BH90 hydraulic hoses over the weekend. Set up one of the calipers with hydraulic fluid and pretty exhaustively bled them and still barely able to get the pads the touch the rotor when the lever is pulled to the bar. I got one of the R7070 105 calipers I ordered yesterday and set that one up and it already seems much better. even without having any time to sit and let the air bubbles settle out, the lever already feels firmer and stops well before I hit the bar. I expect when I go back and finish bleeding them they will feel as good and my GRX brakes.
I still don’t fully understand why the RS505 calipers aren’t compatible especially when the RS505 shifter supposedly works with a 105 caliper, but this seems to be the case.
Thanks again to all those that assisted