Subject: Re: gearing Posted by: Antonio on October 15, 2006 at 23:34:02: In Reply to: gearing posted by surferman on July 17, 2006 at 16:12:44:

Message: >hi i just bought a road bike with ulterga gearing 39 53 chain rings ,, have just changed to a 12 /25 rear cluster still would like lower gearing for the hills ..im 51 and just enjoy getting out for long rides but find i dont use the high gears but could do with some lower ,, would the answeer be to put smaller ones on the front or go bigger on the back ,,or i know i know just get fitter I use a 12-27 cluster in the rear weel and 48-38 chainrings in the crankset. This gives exactly the same LONGEST gear than I had before with the 52/39 chainrings and the 13-25 cassette, and "ONE shorter gear": (38X24 is similar to 39X25) When I'm fit I rarely use the 38X27 because I live in a rather plain location; the 24 cog is enough. If you have 9-speed cassette (and shifters) and have to climb long ramps of 10% of slope, for not too much money, I would recommend a mountain bike cassette (13X30 or 12X34, never a 11X32 because the 11-teeth cog would be useless) BUT ADDING a new LONGER REAR DERAILLEUR (Shimano recommends not TO use rear cogs bigger than 28 teeth with short derailleurs because the spring could eventually fail) If you go for a new crankset, the definitive solution is a triple chainring (I would suggest you 50-42-30 chainrings, and a 9-speed 13-25 cassette -or 12-25 if you are a quick descender-) It is also the heavyest an the most expensive: You have to buy a triple front derailleur and a long rear derailleur. Which I wouldn't never recommend is a compact crankset with a small ring of 36 teeth AND a 12-25 cassette: 38X27 gives a SHORTER gear than 36X25. A good combination could be 48/34 in the front and 12-27 in the rear. Use a gear calculator or -better- a calculus sheet. Which I dislike from the "compact concept" is that I would have to use the big chainring to cruise in plain terrain (most of the time)and with the chain VERY CROSSED, on the 21 or 19 cog, because with the 34 chainring you can only reach 16 mile/hour at 95 r.p.m. Instead, with a triple, a middle chainring of 42 teeth and a 9-speed 12-25 cassette, you can cruise at 15-21 mile/hour and the chain CENTERED in the cassette and crankset. With a triple chainring you can have a wider range of gears than with a compact, but with shorter jumps between one and the next -specially if the compact goes with 9-speed instead of 10-