Author Topic: derailleur/shifter compatability  (Read 415 times)

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
derailleur/shifter compatability
« on: December 27, 2019, 02:32:17 pm »
I have an old 10sp 105 shifter, currently mated to an even older tiagra rear mech (originally 8sp, about 15yo).  Rear mech is getting more and more difficult to dial in accurate shifting and I can't get it across the full range nowadays.

Looking on various websites, I'm concerned about current mech compatibility with the older shifter.  I cant find the model number on the shifter (tried peeling back the hood from both front and rear) so is there any easy way to tell which current derailleurs will work?  I'm needing a long cage btw - use a triple on that bike.
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: derailleur/shifter compatability
« Reply #1 on: December 27, 2019, 02:40:00 pm »
Get an XT 9 speed rear mech. Still readily available.
If you don’t make time for exercise now, sooner or later you’ll need to make time for ill health.

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: derailleur/shifter compatability
« Reply #2 on: December 27, 2019, 02:46:26 pm »
Phil, forgot to mention, this is a road bike - is the XT cable pull compatible with a road casette?
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: derailleur/shifter compatability
« Reply #3 on: December 27, 2019, 03:07:30 pm »
Phil, forgot to mention, this is a road bike - is the XT cable pull compatible with a road casette?

Yep, it's the setup I had on my road bike , now use dura ace 10 speed bar ends with an XT 9 speed rear. . The shifter will determine the pull, the rear derailleur doesn't really have a number of gears. It all works perfectly
If you don’t make time for exercise now, sooner or later you’ll need to make time for ill health.

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: derailleur/shifter compatability
« Reply #4 on: December 27, 2019, 03:24:32 pm »
that's kinda what I thought, but (at least some of) the newer rear mechs have a different geometry that affects movement for the same cable pull.
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: derailleur/shifter compatability
« Reply #5 on: December 27, 2019, 04:42:17 pm »
This is quite a clear description that I've referred to a bit https://bike.bikegremlin.com/1278/bicycle-rear-derailleur-compatibility/
It seems that the road / MTB different cable pull (and also the distance the mech must move from low to high?) mostly starts with 10 speed.

If it used to work well and now doesn't that sounds to me more like something wearing out than a compatibility problem - though something on the edge of working might well go over that edge rather sooner.

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: derailleur/shifter compatability
« Reply #6 on: December 27, 2019, 05:04:13 pm »
thanks Dan I will take a look.  I don't have a current compatability problem.  I have a very old rear mech that I think is now pretty worn and causing these problems, as you speculate. 
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: derailleur/shifter compatability
« Reply #7 on: December 27, 2019, 06:21:36 pm »
that's kinda what I thought, but (at least some of) the newer rear mechs have a different geometry that affects movement for the same cable pull.

If you get 9 speed Shimano mtn mech you'll be fine
If you don’t make time for exercise now, sooner or later you’ll need to make time for ill health.

Re: derailleur/shifter compatability
« Reply #8 on: December 27, 2019, 07:13:57 pm »
compatibility-wise you can use any shimano RD (excepting 7400 series and 4700 series) 6s to 10s or any shimano MTB RD 6s to 9s and it will shift correctly with your 10s shifters on a 10s road cassette.

An 8s tiagra RD is liable to wear out and get to the point where the thing simply won't be reliable any more.  You don't say which 10s 105 shifters you have but IME they are slightly finicky with 'washing lines' and  if the routing is under the bartape they are a very common cause of trouble. 

cheers