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Tiagra 12-30 cassette - fitted to existing drivetrain?

arlowoodarlowood Posts: 2,554
edited May 2012 in Workshop
Hi there

Just about to pull the trigger on one of these Tiagra cassettes to retrofit to my current drivetrain.

Currently have a Dura Ace compact chainset with an Ultegra 10-speed 11-28 cassette and Dura Ace rear mech.

Just completed the short route on the Rutland CICLE Sportive yesterday and managed to cope with most of the steep hills on the 34-28 combo. However there were a couple of short sharp digs in places where I ran out of power.

Was thinking that with a 34-30 lowest gear I could have conquered the real killers. My rationale is that with my old Spesh Secteur triple I could grind up more or less anything on the granny combo (30-27) and this is almost identical gearing to a 34-30 set up. Also the make up of the 12-30 cassette means that I will still have the same ratios through 90% of the cassette with a 27 and 30 tooth lower combo rather than a single 28 tooth as now.

I know there will be those who say - just get fitter. However with my advanced years(67) there is only so much margin for improvement in the fitness stakes.

Just wondered if anyone has done this modification and whether it worked OK. What adjustments might be necessary to make it work - B-screw, chain length? - or will I just have to live with my existing set up?

I'm thinking that at £26 it might just be worth the gamble.


  • jibberjimjibberjim Posts: 2,810
    It's really pushing the rear derailleur capacity - the Tiagra 10speed has a wider capacity one, and there's a 6700A out sometime around now to widen it in ultegra. However some people do get lucky and it's okay, others not. It simply depends on the exact chainstay length and chain line and stuff I think.

    you can go cheaper than 26 too e.g. ... aid:519986
    Jibbering Sports Stuff:
  • weatyweaty Posts: 122
    I just went through something similar on my daughters bike, I found an article on sheldon brown which said you should be 0k with a medium cage mech and a 12-30 cassett, just adjust the B screw. I have just looked for the article but cant find it again, sorry.
  • arlowoodarlowood Posts: 2,554
    Hi guys

    Bumped this to report on my experience with swapping my 11-28 cassette with the Tiagra 12-30 cassette on a Dura Ace GS rear mech married to a compact Dura Ace crankset.

    Cassette arrived yesterday. Swapped it over this morning. Stuck with my existing chain to see if it would work OK but had a new 10-speed KMC chain in reserve just in case.

    Everything went like clockwork - gear changes were smooth straight away with no need to touch anything in the way of b-screw, H/L screws or indexing. Checked the chain angle through the jockey wheels on the 50-30 (big/big) combo and all was running fine with a still discernible angle to the chain path. I never ride big/big or small/small but just wanted to check that there would be no mangling if I did change to those gears by mistake.

    Just back from a 20 mile ride and I can report that the Tiagra cassette is great. Got the same ratios in the middle of the cassette as the old 11-28 Ultegra but now have that extra 34-30 ratio as a bale out gear when I hit those unexpected gradients on a long sportive.

    All I can say is that it has worked fine for me so if anyone else is considering it as an option for a hilly sportive then give it a go. Even if you have to swap to a longer chain, it's only an outlay of £50 tops for the chain and cassette. You can always swap back if you want to get back to higher gearing.
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