Canardweb Posted January 16, 2010 Report Share Posted January 16, 2010 Hello, I have to stop trials and sell my bike because of huge financial problems. But when I am back to Trials (in 3 or 4 months if I am lucky), I would like to buy that 24" because trials frame. I would now like to know, what would be the gear ratio I should use as I want something equivalent as 18:15. I made some mathematics, but couldn't find the operation I had to do... Please help. Quote Link to comment Share on other sites More sharing options...
chris4stars Posted January 16, 2010 Report Share Posted January 16, 2010 If you want to find equivallent gear ratios: 18:15 = rear wheel turns 18 times for every 15 turns of the crank this works out as 1.2 turns of the rear wheel per turn of the crank (18 divided by 15) so in effect 18:15 can be written (in terms of ratios) as 1.2:1 When looking (if buying used and you dont have the option to specify the ratio) Divide the number of teeth on front chainring by the sprocket and you'll have your ratio If the answer is higher than 1.2 it will be easier to pedal than the 18:15 and vice versa Quote Link to comment Share on other sites More sharing options...
Luke Rainbird Posted January 16, 2010 Report Share Posted January 16, 2010 That doesn't take into account the change in wheelsize, so whilst you'd get a matching ratio it won't work on the smaller wheels. Assuming you're coming from stock as your profile suggests, you'll want to run 18:14 to get the closest feeling ratio. This is assuming you'll keep the 18t up front, 22:17 on 24" wheels is almost identical to 18:15 on 26" wheels Best way to get a direct comparison that takes into account the wheelsize is to get your ratio (ie. 18/15) and multiply it by the size of the wheels (26) - this gives a figure that you can then directly compare to each other as it's relative to the distance one revolution of the wheel will provide as opposed to the cranks. Multiply by pi if you want to be really pedantic and get the actual distance moved, but being a constant value there's not really much point Quote Link to comment Share on other sites More sharing options...
Simpson Posted January 16, 2010 Report Share Posted January 16, 2010 If you building the bike from new get 16-12 I ran it was beast, and you can obv run the smaller lighter bash rings Quote Link to comment Share on other sites More sharing options...
chris4stars Posted January 16, 2010 Report Share Posted January 16, 2010 (edited) Ah...sorry about that, didnt realise you were meaning you wanted the equivalent ratio on a 24" from 18:15 on a stock I should go back to bed...listen to luke! Edit* save weight?! i dont think the extra 20 grams should be even thought of when considering your ratios really...get what feels right Edited January 16, 2010 by chris4stars Quote Link to comment Share on other sites More sharing options...
Canardweb Posted January 16, 2010 Author Report Share Posted January 16, 2010 Ok thank you so much! All I have to do is sell my bike then! And find a job... And get my bank account to zero... And save some money... That will take ages! Cheers! Quote Link to comment Share on other sites More sharing options...
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