Problem shifting into large chainring
I have a Shimano 78X dual chainring which was bought brand new originally as a 28/40. However I have overestimated myself and I have been struggling with some of the climbs over here in my trails in 28T. I have bought new chainrings from Blackspire (26/36). While climbs are much better now, I face a new problem. I find it difficult to shift from small CR to the big one (Maybe 1 successful shift out of 6-8 tries). Turning the clutch off my XT RD, makes it slightly better but I would still get about 1 success out of 3-5 tries.
So far 3 shops have now taken a look at my bike and tuned the shifter/FD now. Problem goes away for 2-3 rides before it happens again.
Shop 1 said - Try to use Shimano rings as Blackspire rings are difficult to shift.
Shop 2 said - It's normal for a tuneup every once in a while (Salestalk I believe! My other commuter bike's last tuneup was 1.5 years ago)
Shop 3 said - He can't do much to improve the shifting but suggested that I get a 9 speed FD so that the "throw" is further.
I got desperate, ran to the library to get an encyclopedia looking bicycle maintenance book and tried DIY-ing. I have turned the H setting counter clockwise all the way & it didn't seem to improve either. Any ideas what I should do?
How smooth does it attempt to shift when you try? If it's not like butter, then perhaps new a cable and housing(s) would smooth things out?
I personally do not think it is the problem with the cables/housing (yet) as the shifting/cable movement feels firm but smooth. When I try to shift from the smaller ring to the larger one, the FD moves but it just doesn't push the chain onto the larger ring and this causes that familiar "krak krak krak" sound when you pedal, cadence and speed remains the same and when you look down on the CRs, you can see it's not shifted up. So I'll have to shift down to eliminate the noise and try again. Repeat until successful.
Originally Posted by Hawg
BTW, the bike is about 6-9 months old max.
It shifted into the 40 tooth big ring fine before you changed to a 36?
It worked fine with the original Shimano rings. The LBS that did the ring swap (& FD tuning) told me that Blackspire rings does not always shift properly somehow. I don't wanna entirely believe or diss him but if this was such a bad company, they wouldn't have had a good rep globally and be in business for so long, I guess?
Originally Posted by Hawg
It sounds like the shift points on the big ring or your cable or both. You said it "feels firm but smooth". It should shift almost effortlessly as far as pushing on the lever goes, not firm. At 6-9 months old, if you've ridden it regularly, it's time for a new cable, IMO. Curious to see if that helps the situation.
Have you contacted Blackspire?
Does the FD position the chain properly to where it should move onto the big ring when you shift up to it?
I think this is key. SOMETHING is moving or gradually changing that shouldn't.
3 shops have now taken a look at my bike and tuned the shifter/FD. Problem goes away for 2-3 rides before it happens again
A 2-speed FD is a pretty simple device. It has two positions. The low position is set by the low limit screw. You aren't having any problem with it shifting down or coming off the inside of the little ring, so that isn't the problem.
Cable tension sets the high position, assuming the H limit screw isn't turned in too far. The H limit screw just keeps you from shifting off the outside of the big ring).
Check for obvious stuff. Make sure that the clamp is tight and the FD isn't moving on the frame. Make sure the chainring bolts are tight.
But I'm guessing it is the cable or shifter. See if the FD shifts OK when you do it manually by pulling where the cable attaches while someone else turns the crank.
Check the cable attachment at the FD to make sure it isn't slipping. If that slipped, it would explain why it works for a while then stops working.
Check the cable jacket ends and the things that attach them to the frame (what's the proper term for them, anyone?) Remove the jacket or slide them aside and clean and lube the cable. I wipe them down with dry chain lube.
Some other things to check: On my Shimano there are ramp pins. They should be at right-angles to the crank. The logo should go opposite the crank. (I have installed them wrong and it didn't make much difference).
Make sure the up-down position of the FD is correct. There are landings and ramps inside the cage that should be positioned properly. Again, I haven't found it to be critical though.
Re: Problem shifting into large chainring
I bet its not the rings unless something went wrong during fabrication. Been using dual blackspire rings for a year now without problems.
Did you check the cable tension? If it is firm shifting, maybe the cable is too tight?
And check all the points the previous poster mentioned...
When the new rings where fitted did they move the derailleur on the frame.
It may be they haven't moved it or that they've set it too low/high.
I'd be tempted to refit the derailleur from scratch (search YouTube) and whilst the Der is off I'd relube the cable and all the pivots & springs and check its full movement.
You said it was working previously so it sounds more like something hasn't been properly adjusted during the set up.
MTB: Stumpy, Enduro, Hotrock, Commencal Supreme
ROAD: Jamis Zenith, Pinarello Dogma
My apologies if I used the word "firm" wrongly. Yes, it is near effortless to shift but yeah, I think cables is something I have not looked at before.
Originally Posted by Hawg
Blackspire's answer was short and simple. There are so many possibilities so please bring your bike to a professional.
Originally Posted by DennisF
Makes plenty of sense. Let me try figuring this myself (Hopefully learning a thing or two) but if it fails, I can just bring the bike to a LBS and learn from them.
Originally Posted by griffter18
Dennis F would be correct, I think, based on the info you provided; sounds like the derailleur is slipping down the seat tube. Loosen the clamp screw just enough that the derailleur moves with finger pressure, but not by itself. Position it so that the outer face of the cage is 1-3 millimeters above the large ring, and that the inner plates are parallel to the rings (mind you, you will need to slightly toe the derailleur while it is loose, and it will straighten out as you tighten the clamp band). Tighten the clamp band. 5 NM should do it, assuming you have a metal frame. You will likely need to adjust the cable tension after these adjustments, assuming you didn't have to remove the cable altogether.
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