Looking for some help to get my bike to shift smoothly in the middle of the cog range. I have TT900 shifters with SRAM red rear derailleur and SRAM 11/25 cassette. The shifting is fine at both extremes of the cassette, but often skips or misses a shift when I’m in the mid range.
Eg. I go to shift up a gear, it tries, but the derailleur doesnt move enough to make the shift, so I get that annoying “not quite in gear” sound. If I shift up one more, it moves up 1 cog but is still 1 cog behind, and so still making that noise. If I keep going up eventually it jumps 2 cogs and synchronization is restored.
It shifts fine on the bike stand at all times, I only seem to have this problem when shifting under load. So does anybody know how I fix this please? Thanks.
Let’s assume the problem is not a worn out derailleur, shifter, cogs or chain. That leaves the cable, housing or refining the adjustment. If the cables/housing are older I’d start by lubing them and making sure the cable is clean and no build up of dirt. If cables/housing are new I’d lean towards just fine tuning the adjustment. Try some very small adjustments of the RD barrel adjuster.
Thanks. All the gruppo is <500 miles, so it shouldn’t be wear. I just changed the cables when I switched from brifters to a TT set up. I’ll try tweaking the barrel adjuster like you suggest.
It shifts fine on the bike stand at all times, I only seem to have this problem when shifting under load. So does anybody know how I fix this please? Thanks.
What bike or frame do you have?
Goto SRAM’s website and look at the product manual. It has all the troubleshooting you need. Sounds like you have the high and low limits set now you need to fine tune the cable tension.
Once you’re in the correct gear, do you hear any rubbing/rattling/clicking/etc? Your limits sound like they are adjusted correctly, and cable tension also sounds correct (as you indicate that shifting is fine in both extremes. If cable tension were the culprit, your low shifting would be wonky as well.) It sounds like your cable isn’t travelling smoothly through the housing. Disconnect the cable from the rear derailluer and try manipulating the cable by hand. It should feel VERY smooth and easy to slide through the housing. If it feels gritty or tight replace the housing. Take care to make sure the housing ends are not pinched and that the cable passes through the ferrules easily. I like to apply lube to the inside of the housing (NOT wax based!) as it reduces cable-housing friction and helps prevent dirt and other road detritus from getting into the housing and gumming things up.
Also, as another poster mentioned, check your der. hanger. If it is out of alignment you will want to get it straightened, and then re-adjust your limits and cable tension.
Thank you for all the help everyone. I played with the rear barrel adjuster out on my ride yesterday, and that definitely improved things a bit, though I still have not got it quite perfect.
Regarding the housing, that might be the culprit. I cut the housing with a dremmel (my park cable cutters always pinch the housing so I stopped using them) but i found the dremel seemed to melt the inner plastic at the edge of of the housing a little (sometimes the end was completely closed, but the metal wasnt pinched). I tried to fix this by feeding an old cable through and then wiggling it at the end to push the plastic back out. What do people normally use to cut housing to avoid squished ends or melted plastic?
The bike is a cervelo soloist. Because the cables feed partly through the tubing and are exposed under the BB, I’m wondering if I need to lube the little plastic bit under the BB. This area gathers grit/ dust and that can’t be good for shifting.
The derailleur looks straight, but I will check again to make sure. When it is in gear there is no noise/ rattling/ rubbing/ clicking.
don’t lube the BB cable guide, it’ll just collect more dirt; definitely clean it though.
you can use the cable cutters, just take a file to it to smooth it out, or if you do the dremel use a knife or something with a point to smooth out the hole for the cable.
I dont think it’d be the derailleur hanger. If the hanger is bent usually it’ll shift good on either the high end or the low end but not both and bad in the middle; imagine if it’s not square it get’s more out of square the further it moves making it shift worse. But either way that doesnt hurt to have your LBS take a look at it to ease your mind and let you refine where the problem is; it’ll be hard to measure by eye, you’d need a tool to know for sure.
I’d keep dialing in that barrel adjuster. I recall reading that SRAM says the top jockey wheel is supposed to be positioned just to the outside of your small cog. Although as others have mentioned your lower limit screw sounds like it is correct since it’s shifting good at the bottom and the top, but it doesnt hurt to check, and if you adjust your lower limit screw you’ll have to start over with your cable tension.