Lowering gearing?
lvquestpaddler
Posts: 416
My bike has 36/50 by 12/25 gearing, I'm nowhere near race fit but given my hilly location I was wondering if it's possible to lower the gearing inexpensively? A triple chainset would have been better but the bike was dirt cheap, but can I get a lower ranged cassette (currently Shimano HG50 spec) to work with a 9spd Tiagra drivetrain? :?
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I was just on Wiggle and found a Truvativ Touro triple chainset for £47, given that it's the double I have could I buy one and swap it over. Would the Tiagra shifter work ok with this (it seems to have an intermediate position requiring a double click to get between the 2 chainrings and allows for "tuning" of the position if using full range at the cassette(ie smallest chainring and smallest cassette sprocket....ps- I know it's wrong and ruins the chain!!)
Or would I have a double specific shifter?0 -
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IMHO buy a 34 or even a 33 tooth small ring for the front and a 12-27 for the rear.
This should get you up all but the really long, really steep climbs and maybe even up them.0 -
Good replies, thanks! Found shimano spec for the doubles which says that if the cage is SS it can take a max of 29T, so it can take a 28T ok.
The only cassette I can find suitable is the HG80 (11/28) at £36, anything cheaper around?
Would I need a new chain for the extra 3T?0 -
lvquestpaddler wrote:Good replies, thanks! Found shimano spec for the doubles which says that if the cage is SS it can take a max of 29T, so it can take a 28T ok.
The only cassette I can find suitable is the HG80 (11/28) at £36, anything cheaper around?
Would I need a new chain for the extra 3T?
Can't say about cheaper 11-28's, but an 11-28 should be good to go on you rear mech.
As for the longer chain. It's hard to say without actually seeing the bike and working the gears. LBS could help there.
There is still the option for a 33 or 34 front ring for even lower gearing.0 -
Starting to get somewhere- Evans have SRAM PG950's in 11-28T for £22.99, result!
Found this site and was wondering if the 34T chainring would be better,or go for both.
http://www.cyclesportsuk.co.uk/product_ ... ts_id=4259
Will probably buy a PC951 chain cos I've always used them on my MTB(powerlink makes removal and cleaning so much easier)
Only concerns of making changes are vastly messing up the gearing. Can't find any info on the individual sprockets in the 11-28 and how that compares to the current 12-25?
I've no intentions of ever racing just want a cheap and useable bike. At present there's gears I'll never use!!!0 -
Just ordered a 34T, good advice Dennis. What swung it was googling about bike gearing and found a superb calculator on Sheldon Browns site which allowed me to put in the different permutations of a 34T chainring and/or 11-28T cassette and compare on a given basis of "MPH@90RPM" for example. The cassette change alters everything obviously and the higher gears would be utterly useless, but in changing the chainring I could see the difference in the lower chainring but there was still a useable spread with no large jumps and the upper ring still close ratios.
Will see how it goes!
(PS easy to copy and paste each set of calcs into excel and have side by side comparison)
http://www.sheldonbrown.com/gears/
Cheers for all the advice! 8)0 -
The 34 chainring is a good choice as the 11-28 has wide ratios in the cruising gears, as you observe.
12-28 would give a more useable gear ratios, but SRAM are always trying to compete with the range of a triple - because they dont have one.
I have started using a 12-29 custom set up on my 10 speed Campag compact set up and this works well, although I would prefer the triple for a major Alpine tour -wider range and closer ratios = improved performance.0 -
Still waiting on the chainring but as I posted elsewhere in the "sticky" topic got some top advice on mix'n'matching cassette sprockets and used the 28T from an HG50 MTB (11-32) and dropped the 14T from the 12-25 so have 12,13,15,17,19,21,23,25 and 28. Took the bike on a training route last night and it's made a big difference already!!
The chainring should hopefully be enough to keep me happy(and if I lose 2st it would help immensely!)0
