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-   -   Ultegra R8000 RD Shift Vagueness (https://www.bikeforums.net/showthread.php?t=1199547)

Buzzkill53120 04-27-20 02:53 PM

Ultegra R8000 RD Shift Vagueness
 
I upgraded my Madone with an Ultegra groupset three years ago. My question is about RD downshifting (larger->smaller cogs). It feels vague to me. Earlier in the season I replaced only the shift cables figuring I only need to do them. Uncertain if this was the problem, I replaced cables and housing with Jagwire Pro set. Shifting feels a little better, however the downshifting still feels vague to me. I'm not having any shifting problems, however it doesn't feel as crisp as I think it should be.
Could this be all in my head? I have another bike that I rode all winter on a trainer, equipped with SRAM RIVAL. It's shifting is not as smooth, but it's downshifting is definitely more positive. Could this be a problem with the shifter or the return spring on the RD? Has anybody else had a similar situation?

grizzly59 04-27-20 09:54 PM

Large to small is done by cable slackening, and the derailer spring doing the shifting. Is the cable routed correctly around the BB shell? Cables probably have a stainless or plastic guide, check that. I would clean the cable where it goes inside the housing, I use a bit of silicone grease on the cable then put the housing back together. Check the head end of the cables for fraying, scraped coating gumming up the works.

Recent helpful thread:

https://www.bikeforums.net/bicycle-m...y-indexed.html

Buzzkill53120 04-27-20 10:31 PM

Installed new cables and housings today. Inspected the replaced cable/housing and BB routing, didn't find anything unusual. Extra careful when cutting the housing. I run a piece of cable in the housing when I cut it and then push a icepick in the end to ensure it is not crimped. It does feel like a weak RD spring, but I don't have reference point to compare. Everything has been cleaned and lubed.

grizzly59 04-27-20 10:44 PM

Try screwing the cable adjuster clockwise 1/2 turn (more slack), maybe you're biased to shift too quick smaller to bigger, too slow bigger to smaller.

ridingfool 04-27-20 10:55 PM


Originally Posted by grizzly59 (Post 21443077)
Try screwing the cable adjuster clockwise 1/2 turn (more slack), maybe you're biased to shift too quick smaller to bigger, too slow bigger to smaller.

Just get di2 and be done with it

Buzzkill53120 04-28-20 08:51 AM

The problem is not with shifting, I got that dialed in to my satisfaction. I'm thinking that the shift mechanism is the cause of the vagueness. Perhaps its the mechanism is worn, gummed up or damaged. I did add some lube to spot I could get at, that didn't help.

jbucky1 04-28-20 09:16 AM

If you have been riding a SRAM system a lot prior to getting on you Shimano it may strongly explain the sensations you have. SRAM is much more of an clunck downshift, shimano is more subtle and may feel like something is wrong.
Do you have a buddy with a Shimano setup to compare?
I highly doubt its the spring in the derailleur.
Other smaller thing to check is your chain wear, cassette wear and derailleur hanger alignment - these can affect how the chain drops.

james
www.buckyrides.com

Buzzkill53120 04-28-20 09:28 AM


Originally Posted by jbucky1 (Post 21443589)
If you have been riding a SRAM system a lot prior to getting on you Shimano it may strongly explain the sensations you have. SRAM is much more of an clunck downshift, shimano is more subtle and may feel like something is wrong.
Do you have a buddy with a Shimano setup to compare?
I highly doubt its the spring in the derailleur.
Other smaller thing to check is your chain wear, cassette wear and derailleur hanger alignment - these can affect how the chain drops.

james
www.buckyrides.com

Yeah, I'm thinking it may be all in my head. Chain and cassette wear OK. Hanger alignment good.


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