Changing gear ratios - advice sought

gbfawa

Hi,
I am off to the South of France in September and will be cycling up some big steep hills. I have a standard road bike with a truvativ compact at the front and sram 9 spd cassette at the back.
I would like to lower my gears, but the only options I can see are to
1) change small chain ring from 36 to 34
2) change cassette from 12-26 to 12-27
I still don’t think this will be enough. Does anyone have any ideas short of converting to a triple? Despite much browsing I cannot find a cassette which goes to 29 or 30, it seems to go from 27 straight into the ‘megarange’ area. I could get a new rear derailleur to accommodate this, but I would like to avoid this level of tinkering if possible.
Thanks!

nicklouse

have you looked at MTB cassettes? 34/11 and 32/11 in 9spd are common.

and may work with your mech depentent on what the range of it is. what rear mech is it. your not running a campag, cassette are you?

gbfawa

the rear mech is tiagra. Apparently it has a nominal largest sprocket size of 27, but in reality you can go up to about 30. I think 32 or 34 might be a bit much.
The cassette is SRAM, which I think is shimano compatible

nun

gbfawa wrote:

Hi,
I am off to the South of France in September and will be cycling up some big steep hills. I have a standard road bike with a truvativ compact at the front and sram 9 spd cassette at the back.
I would like to lower my gears, but the only options I can see are to
1) change small chain ring from 36 to 34
2) change cassette from 12-26 to 12-27
I still don’t think this will be enough. Does anyone have any ideas short of converting to a triple? Despite much browsing I cannot find a cassette which goes to 29 or 30, it seems to go from 27 straight into the ‘megarange’ area. I could get a new rear derailleur to accommodate this, but I would like to avoid this level of tinkering if possible.
Thanks!

You could order a Century 12, 12-30, from Harris in the States, or maybe just get your
LBS to customize a cassette for you.

http://www.sheldonbrown.com/harris/k7.html#9cassettes
Failing that put a MTB cassette on the bike something like a XT 12-34, but just don't use the 34 as your present derailleur will not be able to handle it.

You also might consider going to an 8 speed cassette as there are 11-30 out there

http://www.sjscycles.co.uk/product-Shim ... e-1311.htm

gbfawa

Thanks, the US ordering option is quite attractive at the moment with the exchange rates at nealy 2:1!

andyp

Have you ridden up 'alpine' type climbs before? And do you intend to carry luggage?

Clearly I don't know your ability as a rider but a 36x26 gear is pretty low and should get you up most climbs regardless of how knackered you are. The climbs in the mountains of France don't tend to be steep, i.e. the gradients average less than 10%, but the length is what shocks most British riders.

gbfawa

I haven't ridden in france before and won't be carrying luggage. It's the length that I'm thinking about. I'd like to ride at about 70 rpm and maybe 6mph which works out at quite a low gear. I've ridden some big hills in this country (Bealach na ba) with what I've got but it ends up in a zig-zagging across the road 4mph grind.

John.T

Have a look at this chainset. You may need a longer cage mech with it but you will get up anything with it.
http://www.spacycles.co.uk/products.php?plid=m2b2s109p22

nun

gbfawa wrote:

I haven't ridden in france before and won't be carrying luggage. It's the length that I'm thinking about. I'd like to ride at about 70 rpm and maybe 6mph which works out at quite a low gear. I've ridden some big hills in this country (Bealach na ba) with what I've got but it ends up in a zig-zagging across the road 4mph grind.

You sound a bit like me, although I often have a big saddle bag on my bike for overnight trips. But back to gears - I found a 50/34 compact to be over geared for my fitness and riding style. I generally move along at 17 to 18 mph and I like a cadence around 80rpm.On the flat I don't get above 20mph very often and I like to have a few granny gears so I can spin up hills. So I took a 110/74 triple crank and I use it as a 42/26 "compact" putting the rings on the middle and inner positions. Coupled with and 11-34 cassette I get 103" to 21". The range works well for me, I can get upto 25mph doing 80rpm in the 42x11 gearing and the 26x34 will get me up a vertical wall. The only thing I loose is the ability to crank hard down steep hills, but realistically after 30mph I'm freewheeling anyway.