Tiagra gearing

[GrahamS]

After a year of happy riding I have just switched from a Carrera TDF to a Genesis Volant 20 (tiagra). Loving everything about the Genesis apart from I have run out of gears going downhill a few times as it is a compact with a 12-28 cassette.

Following excellent advice from this board I fitted the Carrera with an 11-32 cassette to compensate for the standard 52/42 chain set. This gave me the easy gear I needed to get my 16 stone up the hills and kept the massive gear needed to catch my skinny mates as we came down the other side, the big 52 x 11 gear was also useful for (short) intervals on the rollers. The set up on the Carrera did give me some fairly big gaps between gears which I learnt to live with, but working my way through the gears on the Genesis is a bit of a revelation.

I would like a to put bigger chain rings on the Genesis and maybe compensate with a 12-30t cassette. Would this be as simple as changing chain rings or would I need to change the whole chain set? If I put a 52t chain ring on what would my options be for the smaller chain ring? (I hope I have the terms right!)

Thank you!

Graham

 

[Hacienda71]

You will probably need to move the front mech up a bit so it doesn't foul the chainring and in theory you would need a longer chain. Other than that as long as your BCD is the same on the new chainring it is possible. The downside would be a massive drop from a 52 to your inner ring. I find a compact an unpleasant drop so you may want to change the inner ring at the same time as well.

 

[I like Skol]

.....or improve your pedalling cadence. I find my compact 34/50 with an 11T rear sprocket is great for 50mph down hill so doubt you would need more unless you are exceeding 55mph?

 

[cyberknight]

.....or improve your pedalling cadence. I find my compact 34/50 with an 11T rear sprocket is great for 50mph down hill so doubt you would need more unless you are exceeding 55mph?

What he said

 

[Nigelnaturist]

Try a 36/52 up front, I get most places on a 38x12-27 with in inner 26 and outer 50, ok I spin out about 36-37mph, my my gear range is 25-109"
On a 36/52 with 11-32 it would be 29.6-124.3" low end being about the same as a 30x27 so pretty low.

 

[KneesUp]

Not sure what model front deralieur you have, but you should check the capacity. The 9 sp Tiagra has a 16 tooth capacity, so 52/34 is too big a drop. Although you might get away with it I doubt it will be 100% reliable or smooth.

 

[Nigelnaturist]

Not sure what model front deralieur you have, but you should check the capacity. The 9 sp Tiagra has a 16 tooth capacity, so 52/34 is too big a drop. Although you might get away with it I doubt it will be 100% reliable or smooth.

Only guessing here "Genesis Volant 20" might be 10sp, as for capacity I run a FD5703 with a chainset of 50/38/26. total of 24th designed for 20/22 th

 

[GrahamS]

Thanks for the replys! I have had a play with gearing calcs and I think just replacing the 12-28t cassette with an 11-28 would sort me out. There isn't a tiagra cassette like that, would I be right in thinking an old 10 speed 105 cassette would work?

 

[smokeysmoo]

There isn't a Tiagra cassette like that, would I be right in thinking an old 10 speed 105 cassette would work?

Any Shimano 10 speed will be OK, so 105 or ULTEGRA will work fine

[EDIT] Good shout by @I like Skol on the Sram cassettes, slipped my mind they did, d'oh! LINKY

 

[GrahamS]

Thank you!

 

[I like Skol]

also look at Sram 10spd cassettes as these will work as well if not better and often come in different gear ranges

 

[I like Skol]

11-28 Sram PG1050 here in equivalent spec to Tiagra

 

[GrahamS]

Thank you, 10 speed 105 cassettes are £15 cheaper at the moment, is the SRAM worth the extra money?

 

[I like Skol]

Thank you, 10 speed 105 cassettes are £15 cheaper at the moment, is the SRAM worth the extra money?

I have tried 9spd Tiagra against the 9spd PG950 cassettes and would say the Sram was the clear leader but I don't have any experience of the longevity of 105 cassettes to say how good they are.