I inherited an interesting Curloo Tri bike, I believe built in the late 90’s. It has a Shimano 105 group set but the cassette is only a close ratio 9 speed. Can I upgrade to a 10 or 11 speed cassette or do I need to consider a new modern group set? The chainrings are 54/39. Thx

  • I doubt that the rings are 54/39 unless custom, but probably 53/39. That set aside you may have some options with the cassette, although various 9-speed are hard to find. But Shimano and SRAM are interchangeable and you may find some uncommon stuff. – Carel Oct 28 '18 at 21:02

You can't just drop in a 10/11 speed cassette; 10 and 11 speed road sprockets are spaced differently than their 9 speed counterparts; a 9 speed shifter will not move the chain the right amount for use with a 10 speed cassette without additional hacks (restricting chainstops, an adapter pulley).

I'd suggest just getting a new 9 speed cassette with more favorable gear spacing. If the chainring sizes bother you, you could also put on a new crankset.

If you choose to go to 10 speed or 11 speed, you will need at a minimum a new shifter; 11 speed will need a new derailleur as well. And the shifter is probably the most expensive part to buy; buying the entire groupset might be a better deal (though questionable on value for a 20 year old bike). On top of that, 11 speed road hubs are wider than 8/9/10 speed road hubs, so you're likely going to buy another wheel if you do a 11 speed.

  • My understanding is that Shimano 10 speed road (except Tiagra 4700) continues the same shift actuation of 1.7 that 7,8,9 speed systems utilize. Therefore a 10 speed road cassette would work in a 9speed deraileur system. The incorrect number – Jeff Nov 7 '18 at 19:52
  • To finish my thoughts: The incorrect number of detents in the shifter is a problem...especially this way (more cogs than detents). I'm currently running 8 speed cassette with 9 speed shifters with nominal performance – Jeff Nov 7 '18 at 20:00

Depending on the rear derailleur, your cassette options may not go much beyond 27 or 28 teeth on the largest cog. Few if any older Shimano road groupsets could do anything beyond 27 officially (but in reality they have no problems with 28s).

If you're worried about the gear ratio, get a compact crankset. Tour de France-level racers don't need more than a 53, and you're not that strong. You should be able to get a higher-end 9 or 10-speed Shimano compact crankset for about $100 or so, less if you're willing to get a used one. If you go for something like an FC-R400, you can probably find one for $50 or so.

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    Andrew I’ve edited to what I think it was you intended to write, which I agree with. Hope it’s correct please roll-back if I’m mistaken – Swifty Oct 28 '18 at 21:49
  • Problem with quoting prices is they're local to you, in some unknown currency, and tend to change over time. – Criggie Oct 28 '18 at 21:54

All indexing is happening in the shifters and not in the derailleur. So moving to 10 or 11 speed does not require a new derailleur. However, the pull (ratio) exercised by a 10-speed shifter is not always the same as for a 9-speed shifter. See Bicycle Rear Derailleur Compatibility for a discussion of compatibility. My takeaway is that you should be able to move to a 10-speed without updating components.

  • Thanks Christian, good information for me to consider. – Don Mann Oct 28 '18 at 15:18
  • This answer isn't correct. – Batman Oct 28 '18 at 17:58
  • You are right - you need a shifter that now indexes for the desired new number of cogs. – Christian Lindig Oct 28 '18 at 18:05
  • Partially correct. How much the derailleur cage moves for each shifter click is the amount of cable pulled multiplied by the actuation ratio of the derailleur, Shimano 8, 9 and 10 speed systems all used the same actuation ratio, but it changed with 11 speed systems (notable exception is the Tiagra 4800 10 speed which used the 11 speed ratio). – Argenti Apparatus Oct 28 '18 at 22:09

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