R9150 Rear Derailleur Adjustment
10-10-17, 06:47 PM
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R9150 Rear Derailleur Adjustment
Hi everyone. I have the R9150 Di2 groupset with R9170 hydraulic discs and I'm struggling to get the shifting smooth. Symptoms are poor shifts between middle sprockets on the rear cassette. No amount of micro adjustment gets it smooth and it's doing my head in.
The B-tension (B-stop, B-screw...) adjustment is weird on the 9150. There is no tension spring on the hanger attachment so it just flops there until you put the chain on and screw in the B screw. The instructions say in the largest rear sprocket to bring the top cog as close to the sprocket without rubbing. If you do this, the chain flops around in smaller sprockets, so you adjust out the slack there but now the cog is miles away.
This may be a red-herring but I thought I'd ask if anyone has B screw adjustment tips and if you think this may affect shifting? I will also be checking hanger alignment but I'm a bit lost after that.
Thanks.
The B-tension (B-stop, B-screw...) adjustment is weird on the 9150. There is no tension spring on the hanger attachment so it just flops there until you put the chain on and screw in the B screw. The instructions say in the largest rear sprocket to bring the top cog as close to the sprocket without rubbing. If you do this, the chain flops around in smaller sprockets, so you adjust out the slack there but now the cog is miles away.
This may be a red-herring but I thought I'd ask if anyone has B screw adjustment tips and if you think this may affect shifting? I will also be checking hanger alignment but I'm a bit lost after that.
Thanks.
10-11-17, 05:21 AM
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As it turns out, everything affects shifting. B screw position is minor contributor. OP, under load aka chain attached that is properly sized for length, the B rack screw should stay in place...if not, put a hint of blue Loctite on the threads to freeze it up a bit...but almost never necessary.
Your issue could be many things, but losing indexing between gears in back when a cog or two are perfectly aligned is generally due to the frame hanger being slightly bent in either plane. I have built many frames up and quite rare from the factory a derailleur hanger is dead straight both horizontally and vertically. Extremely rare. So I always start with straightening the hanger before any build which such make indexing close to perfect from smallest to biggest cog in back. Also check that the axle of the rear wheel is dead square in the dropout...as a slightly skewed rear wheel will also cause poor indexing. Best way to seat the wheel is with the bike on the ground and not on the stand.
Good luck
Your issue could be many things, but losing indexing between gears in back when a cog or two are perfectly aligned is generally due to the frame hanger being slightly bent in either plane. I have built many frames up and quite rare from the factory a derailleur hanger is dead straight both horizontally and vertically. Extremely rare. So I always start with straightening the hanger before any build which such make indexing close to perfect from smallest to biggest cog in back. Also check that the axle of the rear wheel is dead square in the dropout...as a slightly skewed rear wheel will also cause poor indexing. Best way to seat the wheel is with the bike on the ground and not on the stand.
Good luck
Last edited by Campag4life; 10-11-17 at 05:25 AM.
10-11-17, 05:51 AM
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I had a similar symptom not long ago with my Ultegra 6770 where I had some lazy shifts but only in the middle of the cassette. I took the bike to my mechanic who said my chain was stretched and the cassette was worn to the point where he could tell which cogs get the most use. Knowing I was going to replace my entire groupset with the new Ultegra di2 soon I decided to replace just the chain but it made things worse.
Fast forward to last week when my new Ultegra R8050 derailleurs arrived and I was swapping out the 10 speed cassette for a new 11 speed cassette and found the old cassette lock ring loose, now I had three possible contributors to my lazy shift. Now that I think about it, I made a Franken cassette out of two Ultegra cassettes to get a 12-28T setup because they weren't available at the time and after installing had me feeling a slight hiccup in the middle of the range. So now there's four possible contributors to my scenario, maybe it was misaligned cogs from using two different cassettes, maybe it was the stretched chain, maybe it was the worn cassette, maybe it was the loose lock ring, or all the above?
If all of your parts are new, you can rule out most of what I said above but double check that the cassette is tight and your hub driver isn't chewed up where the cassette slides on which can also cause a slight misalignment of the cogs on the cassette. I'd also just for the heck of it check that your wheel is centered and the length of your chain is correct because one link too many or not enough can make a difference in shift quality.
After installing the new Ultegra R8050 derailleurs, Dura Ace cassette, and DA chain, my bike is shifting like butter. Its amazing how far they've come in a few years, especially up front. That new front derailleur is so much faster and quieter than the old 6770 di2. Hope you get it sorted out so you can enjoy your ride. Let us know what you find please.
Fast forward to last week when my new Ultegra R8050 derailleurs arrived and I was swapping out the 10 speed cassette for a new 11 speed cassette and found the old cassette lock ring loose, now I had three possible contributors to my lazy shift. Now that I think about it, I made a Franken cassette out of two Ultegra cassettes to get a 12-28T setup because they weren't available at the time and after installing had me feeling a slight hiccup in the middle of the range. So now there's four possible contributors to my scenario, maybe it was misaligned cogs from using two different cassettes, maybe it was the stretched chain, maybe it was the worn cassette, maybe it was the loose lock ring, or all the above?
If all of your parts are new, you can rule out most of what I said above but double check that the cassette is tight and your hub driver isn't chewed up where the cassette slides on which can also cause a slight misalignment of the cogs on the cassette. I'd also just for the heck of it check that your wheel is centered and the length of your chain is correct because one link too many or not enough can make a difference in shift quality.
After installing the new Ultegra R8050 derailleurs, Dura Ace cassette, and DA chain, my bike is shifting like butter. Its amazing how far they've come in a few years, especially up front. That new front derailleur is so much faster and quieter than the old 6770 di2. Hope you get it sorted out so you can enjoy your ride. Let us know what you find please.
Last edited by dvdslw; 10-11-17 at 06:00 AM.
10-13-17, 12:50 AM
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Interesting feedback guys. However I should have mentioned that this is a brand new frame, new groupset and thru-axle wheels. I took the bike in to the local shop and we ran the DAG over the hanger - alignment is perfect.
Campag4Life - have you worked on an R9150 rear derailleur? The b stop operation is very different to previous derailleurs thus my question. I don't have any screw movement requiring Loctite.
I've tuned the Di2 to eliminate most of the poor shifting but not through the normal technique of "4 clicks back from upper sprocket rub". It took a fair bit of playing around. Weird all up and maybe I'll have to wait for more field experience to come along.
Campag4Life - have you worked on an R9150 rear derailleur? The b stop operation is very different to previous derailleurs thus my question. I don't have any screw movement requiring Loctite.
I've tuned the Di2 to eliminate most of the poor shifting but not through the normal technique of "4 clicks back from upper sprocket rub". It took a fair bit of playing around. Weird all up and maybe I'll have to wait for more field experience to come along.
10-18-17, 07:20 AM
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Experimenting tonight I came across more info pointing to the B Stop (End Adjust Bolt in the manual) screw being the problem. If I tune the shifting according to the manual and screw in the end adjust bolt to bring the pulley real close to the largest sprocket, the shifting is buttery smooth. Only problem is that there is no chain tension from the 6th cog onwards.
There has to be something in this. Anyone else experiencing this issue?
There has to be something in this. Anyone else experiencing this issue?
10-18-17, 08:12 AM
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Hard to know what's going on redem. Poor shifting in the middle of the cassette is an odd dynamic if both large cogs and small cogs shift ok.
Your derailleur could be defective. I have limited experience with Di2. Perhaps a programming error if the derailleur is indexing to wrong no. of cogs...like 10 speed versus 11s.
What I would do:
1st. check chain length. Incorrect chain length puts more onus on correct chain tension which is largely what the B screw does...which balances derailleur cage spring rate which is what moves the jockey wheel closer or farther from the cassette.
2: I would try another cassette. Spacing of your cogs...spacers used maybe incorrect screwing up indexing in middle cogs.
3. Take to shop and request their advice about the B screw. Don't have to leave the bike. Put bike on the counter and point at the B screw and ask the best tech in the shop to provide their best practice for adjusting the B screw for this model derailleur.
Good luck.
Your derailleur could be defective. I have limited experience with Di2. Perhaps a programming error if the derailleur is indexing to wrong no. of cogs...like 10 speed versus 11s.
What I would do:
1st. check chain length. Incorrect chain length puts more onus on correct chain tension which is largely what the B screw does...which balances derailleur cage spring rate which is what moves the jockey wheel closer or farther from the cassette.
2: I would try another cassette. Spacing of your cogs...spacers used maybe incorrect screwing up indexing in middle cogs.
3. Take to shop and request their advice about the B screw. Don't have to leave the bike. Put bike on the counter and point at the B screw and ask the best tech in the shop to provide their best practice for adjusting the B screw for this model derailleur.
Good luck.
Last edited by Campag4life; 10-18-17 at 08:20 AM.
10-19-17, 05:16 PM
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To finish this thread off, I had a chat with a Shimano support tech and the new derailleurs are quite chain length sensitive. The chain length method shown in the dealer's manual is about 1-2 links out for my setup and they reckon the best way of measuring is to check to see if the pulleys are directly above each other when in the hardest possible gear. It looks like I can take a couple of links out which will tension the chain in the smaller gears and allow me to get the b-screw backed off. Pulleys then come in closer and the shifting gets better.
Thanks for the interest and help guys.
Thanks for the interest and help guys.
10-20-17, 08:36 AM
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rebem,
Reason I put check chain length as no. 1 on my check list recommendation to you is...I suspected your chain length was wrong for certain gear combos which affects chain tension due to B screw adjustment. And of course lack of chain tension affects shift quality.
To be clear, many who try to interpret chain length method(s) to the letter, still get chain length wrong.
You of course have to start with the correct rear derailleur cage length given the tooth difference between small chainring and big chainring in front. Big differences in tooth count in front + a broadly geared rear cassette = need for longer rear derailleur cage length which btw makes chain length even more critical.
Best method is...shift the bike to Big Chainring - Biggest Cog. Yes, a rare X-chain condition but nonetheless one that must be served. On Big-Big the derailleur cage should point well to the right...about 5 o'clock or so. Almost all the rotational travel the cage can give to achieve this position.
If you have too much slack in Big-Big, your small-small will never have nearly enough chain tension to shift properly.
HTH
Reason I put check chain length as no. 1 on my check list recommendation to you is...I suspected your chain length was wrong for certain gear combos which affects chain tension due to B screw adjustment. And of course lack of chain tension affects shift quality.
To be clear, many who try to interpret chain length method(s) to the letter, still get chain length wrong.
You of course have to start with the correct rear derailleur cage length given the tooth difference between small chainring and big chainring in front. Big differences in tooth count in front + a broadly geared rear cassette = need for longer rear derailleur cage length which btw makes chain length even more critical.
Best method is...shift the bike to Big Chainring - Biggest Cog. Yes, a rare X-chain condition but nonetheless one that must be served. On Big-Big the derailleur cage should point well to the right...about 5 o'clock or so. Almost all the rotational travel the cage can give to achieve this position.
If you have too much slack in Big-Big, your small-small will never have nearly enough chain tension to shift properly.
HTH
Last edited by Campag4life; 10-20-17 at 08:39 AM.
