Larger cassette for compact chainset

Ah_go_on

I'm a tall and heavy cyclist with an entry level road bike with a compact (50/34) chainset with 9 speed tiagra mech (11-26 cassette). I'm finding certain hills around Sally gap difficult and would like to make these climbs easier by the cheapest way possible. Would a cassette with a 27 or 28 sprocket make much of a difference and if so am I limited by the derailleur? I don't really want to have to change the mech as mechanically the cassette change would be as much as I could do

velo.2010

Ah_go_on wrote: »

Would a cassette with a 27 or 28 sprocket make much of a difference and if so am I limited by the derailleur?..................... I don't really want to have to change the mech as mechanically the cassette change would be as much as I could do

You should get away with the change to a 27/28 sprocket without having to change the derailleur but I think you'd need a new chain. Also, I think changing a cassette would be considered more of a challenge then changing a mech, unless indexing gears is what your reluctant to do.

funkyjebus

You may need a new chain, depending on how long it is..how long have you had the chain, as it might be a good idea to get a new one anyway to minimise wear on the new cassette.

You may also need a long cage rear mech, if you have a short cage atm. It will pick up the extra slack if you need to add a longer chain.

cdaly_

Shouldn't the compact already have a medium cage mech? I suspect that would manage up to 30t on the rear.

seve65

I switched from 25 to 28, no problem, did change the chain as well though as it was stretching anyway. 28 does make a big difference compared to 25. I think my derailleur might actually be a short cage. The next lowest cog down from the 28 on my cassette is 24, and I do find I dont really want to use the 28 on lets say a 8-9% gradient, but I dont always fancy pushing the 24. But u cant have everything.

Ah_go_on

As I've a 26, would 27 make much of a difference? I've checked out a bit of info on the tiagra mech and it recommends a max 27 cog

seve65

my 105 RD 5600 also said max 27T, if you read sheldon brown he seems to say that the specs from the manufacturers are overly conservative.

Dubba

I went from a 11-25 to a 11-28 with a SRAM Rival setup (which is a big help with the hills) and didn't need to replace the chain or derailleur.
Actually it was my LBS - corkbicycleservices.ie who fitted it for me, took around 10mins with just a few adjustments to the rear derailleur.

coastwatch

Ah_go_on wrote: »

As I've a 26, would 27 make much of a difference?..

It wont make much difference really, but it might be enough, and the fitter you get, the easier it will get. I had the same setup and changed to a 12-27 cassette. I couldn't see how a 28 would fit, but I didn't change the chain (it was practically new) so that probably made it look tighter.

If the 27 tooth cog is not enough help, you could consider converting to a triple chainset. That would give you an extra lower gear and smaller "gaps" between gears. To do that you would need a triple chainset, triple front deraileur and maybe triple front brake /shifter lever (depends which version of the lever you already have). I'm sure you could get all that for under €100 2nd hand as people convert the other way a lot more.

Your LBS would fit all that for you, for a charge.

Plenty of "compact / triple chainset, which is better?" debates here and on the net. I think the triple is a good option for larger riders that like the hills.

Civilian_Target

I had the same problem - I was living in the south of France and I couldn't climb on a double. You could go to 28, it's cheap and easy to do so - you won't get much extra power, but it might be enough for the Dublin mountain.

Personally, I kept the double rolling until the chain was done, and then I moved to a 12-34T mountain bike deraileur on the back which was a huge improvement.