Cassette change from 12-25 to 12-27 or 11-28

Leftfield

I am new to road biking and have found this site an invaluable source of advice and guidance. However after less than 100 miles on my Boardman Road Team and am strongly considering changing the cassette for either a 12-27 or 11-28. I am struggling on any hills and given that I live in south Wales climbing any is unavoidable. With so many good routes nearby I want to have the confidence, and gearing, to know that I will entually get up them no matter how slowly.

Has any changed the cassette on their bike with the same group set, shimano 105 with compact 34/50? Also would I need a new Chain if and when I do change it?

Cheers.

LiberataERedenta

Go for the change if you are struggling up hills.

12-27 will have slightly smaller gaps between the gears so less "jumps", but 11-28 has the better range, sounds like you might like the 28T granny gear though

Chain-wise you'll be fine, no need to lengthen it, just avoid using the big ring-big sprocket combo... in fact any clued-up experienced rider will never use the biggest 2 (or even 3) sprockets in the big ring as you get a bad chainline and ineffecient chain tension anyway.

Failing that there's the SRAM 32T set-up or a triple, but a 34 x 28T should get you up most hills with a bit of fitness

yeachan153

I went from a 53/39 12-25 to a 53/39 11-28 on an 8 speed transmission and the gear ratios are fine, the 28t does help a lot but it won't be that big a difference to suddenly start doing hills you couldn't before with ease.

Worth getting if you are struggling with hills and you also have to option of swapping back to the 12-25t later.

janwal

Last year I ran an 11-28 on a triple for all the hills around Huddersfield.Found it really good as I spent most of my time in the middle ring. However I've just changed bikes and have gone over to a compact. To retain climbing I've changed to a tiagra 12-30.It gives ratios nearly the same as I had before.I haven't noticed the lack of an 11 as I am not a speed merchant and the difference between an 11 and a 12 is not a lot .The 30 is a very useful gear when needed.Also the tiagra 12-30 can be bought for £24 from Parkers
http://www.parker-international.co.uk/1 ... n=pid18668

skyd0g

It's normal to struggle with hills. You will get better. However there is struggling & walking. A good source of advice on understanding gear ratios is here: http://sheldonbrown.com/gears/

Personally, I'd go for the 12-27 to keep the gear ratios closer and to give the extra bail-out gear. You will seldom spin-out on a 50/12.

Grill

I just went from a 12-25 to an 11-28 on a compact (50-34). Definitely better on the climbs and I've found use for the 11 with the big ring as well (although spinning it out does occur on descents).

Bar Shaker

I changed my cassette to an 11-28 (SRAM Force). You don't need to change chains.

the 11 cog is only used going down steep hills and if I were changing again I would probably go for 12-28. There is very little in it though at the top end.

At the big cog end, it made all the difference on hilly routes.

Leftfield

Shimano make a 105 11-28 and a Tiagra 12-28. As the rest of my group set is 105 I would ideally replace with a 105 cassette, however would I notice any difference if I ran with a Tiagra cassette?

yeachan153

You need to check if its 10 speed tiagra or 9 speed tiagra, if its 10 speed its fine

essjaydee

Grill wrote:

I just went from a 12-25 to an 11-28 on a compact (50-34). Definitely better on the climbs and I've found use for the 11 with the big ring as well (although spinning it out does occur on descents).

I did this on my Boardman Road Race. It has helped a bit, but don't expect a massive difference. Easy enough to do, but check your chain length after. You won't need to replace the chain. Make sure you get a 9 speed cassette, if yours is a 9 speed

bikergirl17

would consider the 12-27 if you are on a standard crank set but don't expect a HUGE difference from the 25; i have a 12-23 on my other bike and the only time i notice an appreciable difference is for 15%+ climbs.

was in south wales this weekend, and i powered up the hills vs people on triples. admittedly, frustrated that really thin fit guys were on compacts, spinning away as i mashed up. i did this as an experiment for the alps -- and what is clear is that (a) i would get a bigger climbing boost from using my lighter wheels and (b) need to lose weight on my body, not the bike.

the one caveat is if you live in an area with 25%+ type climbs -- that is compact, 11-28 land.

hodge68

Leftfield wrote:

Shimano make a 105 11-28 and a Tiagra 12-28. As the rest of my group set is 105 I would ideally replace with a 105 cassette, however would I notice any difference if I ran with a Tiagra cassette?

I have 105 and changed from 105 12-25 to tiagra 12-28 and it workd fine, i have a bail out gear, just incase the hill is to big for me.There is a noticable gap in the middle of the cassette, but its not a problem.