Rear Derailleur Shifting Problem

onmebike

I put together some old components (Shimano 105 - 5600, I think - about 10 years old) I had with a new frame and I'm having a problem shifting with the rear derailleur.



To move to a larger cog, I need to press the shifter twice and then go back down one. A single press/click is not moving the derailleur enough to bring it up to the next gear. Shifting to a smaller cog is fine - single click each time.


I've tried adjusting the cable a fair bit, so I'm reasonably sure it's not just that it's out. It's a new cable and housing.



Any thoughts on where my problem might be?

07Lapierre

Derailleur could be worn
Limit screws may need to be adjusted
Chain could be too long/short

My money is on the limit screws. Release the cable and move the derailleur by hand. Ensure it moves the chain onto the largest and smallest cogs.

magicbastarder

limit screws should only affect the outer throw of the derailleur, though? not shifting while between those limits.

07Lapierre

magicbastarder wrote: »

limit screws should only affect the outer throw of the derailleur, though? not shifting while between those limits.

OP says he's having difficulty getting the chain onto the largest sprocket? to me that sounds like the "L" limit screw needs ta 1/4 turn to allow the RD to move a fraction closer to the spokes.

EDIT.. my mistake...its "Larger" cog and Not "Largest" cog.

Zen0

It sounds like the pull ratios on your shifter and your derailleur are slightly different i.e. your derailleur expects a great cable pull for one cog shift than your shifter is providing. If so, there’s no simple or elegant solution. New derailleur.

Edit: reading original post again, if you are using a shifter of the same vintage and a compatible model, then that’s not the problem.

onmebike

Yeah, both shifter and derailleur are from the same family. It's a replacement derailleur, but I don't remember why I replaced the original. I might try the old one to see if that behaves differently.


As chatted about above, the limits are fine once I get there.

kennethsmyth

onmebike wrote: »

Yeah, both shifter and derailleur are from the same family. It's a replacement derailleur, but I don't remember why I replaced the original. I might try the old one to see if that behaves differently.


As chatted about above, the limits are fine once I get there.

How old is the cable, sounds like its stretched, maybe worth a quick replacement.

hesker

Could be your derailleur hanger is out of alignment.

Or could be worn components on your shifter or worn chain.

You can google to find a complete list but I’d start with the hanger alignment

onmebike

It's a new cable, chain and cassette on it, so it shouldn't be any of those consumable parts.


Any tips on checking hanger alignment? I've always just seen it as a static lump and never paid too much attention to them.

hesker

https://lmgtfy.com/?q=hanger+alignment+check

07Lapierre

onmebike wrote: »

It's a new cable, chain and cassette on it, so it shouldn't be any of those consumable parts.


Any tips on checking hanger alignment? I've always just seen it as a static lump and never paid too much attention to them.

Use a plumb line.

Put the bike in a bike stand
Put the chain on the large chainring and smallest cog
Use the plumb line to ensure the small cag and the two jockey wheels of the rear derailleur are in line.

Do the same when the chain is on the small chainring and largest rear cog.