9 Speed Rings on a 10 Speed chainset

ctc
ctc Posts: 232
edited April 2012 in Workshop
Hi,

I've got a 9 speed Tiagra Triple at the moment, and I want to swap to a 10 speed compact. However, this will need to happen over time...

If I buy a 105 10 speed compact chainset now (FC 5750), but then replace the chain rings with Tiagra 9 speed chain rings (50 & 34), and also swap the front mech for a 105 10 speed one (FD 5700), would I be able to run this?

AFAICS (as far as I can see) the only problem might be the distance between the rings on the 10 speed chainset might be less than the 9 speed, but if I adjust the high/low stops on the front mech it should be OK?

What do you reckon - could work?

Comments

  • rpd_steve
    rpd_steve Posts: 361
    It'l work, you may not even notice that it isnt perfect. You may get a couple of bad changes when going from big to small ring but the differance is very minor.
  • GiantMike
    GiantMike Posts: 3,139
    I'm a bit confuced.

    What rings are on the Tiagra triple? Are you planning to use the Tiagra rings on your current chainset on the 105 chainset? Your triple will most likely be 50/39/30 so where is the 34 coming from?

    It's probably easier to sell the Tiagra triple and but a used 105 double, unless I've missed the basis of your question.

    You'll also need to make sure the BCD is the same for the triple and the double to ensure that the rings can be swapped.
  • John.T
    John.T Posts: 3,698
    A 105 Compact chainset will have 50/34 rings fitted so you do not need to use any Tiagra ones. The 105 will work fine with 9sp until you change the rest. As above non of the rings from the triple will fit the 105.
    You do not need to change the rear mech for 10sp compact but it is best to fit a double front mech. The 105 10sp one will work on 9sp but you may need to use the trim a little more.
    Minimum you need for 10sp is Cassette, chain and shifters. Plus chainset and front mech if changing to compact. 105 shifters are either double or triple. Make sure you get the right ones. A short cage mech will look better but is not a priority.
  • ctc
    ctc Posts: 232
    Thanks All,

    GiantMike - I was going to buy the 105 chainset plus two 9 speed chain rings (50 & 34). Swap out the 10 speed with the 9 speed, and when I get the shifters and cassette swap them back. Was just going to remove the old 9 speed triple completely

    John.T - Good to know that I'm fine using the 10 speed chainset with a 9 speed setup. Certainly save having to get hold of the 9 speed chain rings...
  • jomoj
    jomoj Posts: 777
    if you're going to use the triple front shifter with the double chainset, be sure you set it up correctly or you can pretty easily wreck the lever. It's recommended to use the middle and outer clicks for the inner and outer chainring positions, if you use the inner and middle and try and shift into the outer ring click position then you can jam or break the lever internals - which is what happened to me.. :( I just run a single now or at least until i can afford to replace the lever
  • jibberjim
    jibberjim Posts: 2,810
    The 10 speed rings will work fine with 9 speed, you do not need to buy the rings too - just carry on with the full 10 speed chainset. As noted the shimano 2/3 front shifter are pretty ropey when run in the wrong mode - so be careful.

    You don't actually need to change the chainset to go to 10speed anyway, a 9speed chainset and rings will work fine too - so I'd probably not bother with the upgrade you're thinking of. Just get the new right shifter and cassette and you're 10speed.
    Jibbering Sports Stuff: http://jibbering.com/sports/
  • smidsy
    smidsy Posts: 5,273
    jibberjim wrote:
    You don't actually need to change the chainset to go to 10speed anyway, a 9speed chainset and rings will work fine too - so I'd probably not bother with the upgrade you're thinking of. Just get the new right shifter and cassette and you're 10speed.

    You would need a 10 speed chain if you went to 10 speed cassette as the spacing is narrower.
    Yellow is the new Black.