I have a 2004 Jamis Aurora with a 52/42/30 triple and an 11-32 cassette in the back. 30x32 (25.3 gear inches) being the lowest gear is frustrating for the hilly terrain where I live (e.g., 7% grade average over several miles, with higher local steepness), and so I'd like to lower my gearing.
I'd like advice on how to most simply do this. The basic problem is that replacing any given part appears to have cascading compatibility issues which may or may not be solvable, and I'm becoming confused.
I do use the full range up to 52x11 (127.6 gear inches), but only on descents that are fast anyway, so I am happy to lose the higher gears and coast instead. There is essentially no level terrain where I live.
Relevant specs (all parts stock in 2004):
- 9 speed
- Crankset: Truvativ Touro 52/42/30, 130/74mm BCD
- Front derailleur: Sora 28.6mm, clamped
- Cassette: SRAM 11-32
- Rear derailleur: Deore SGS
- Shifters: Tiagra
- Bottom bracket: TruVativ sealed cartridge, 68 x 113mm
Options that I've found so far:
Add a larger cog in back, such as the new Shimano 12-36 cassette. As far as I can tell, this will require a new rear derailleur and a new chain, but that's it. This makes the lowest gear 30x36 (22.5 gear inches), 12.5% lower, and the highest 52x12 (117 gear inches). A downside is the excessive size of the rear cassette.
Replace the crankset, for example with a 48-36-24. This makes the lowest gear 24x32 (20.3 gear inches), 25% lower, and the highest 48x11 (118 gear inches). At first glance, this one is the most appealing, but it seems to also raise the thorniest compatibility questions; the ones I'm aware of so far are (a) finding a front derailleur which is compatible with both my road shifters and the smaller large chainring (one possibility), and (b) differing chainline offsets of road and MTB cranksets.
Swap in a lower granny chainring, say 24 teeth, resulting in a 52/42/24 crankset. My concerns here are (a) whether my derailleur can handle the 18-tooth jump between low and middle and/or the lowness of the granny gear, (b) the awkwardly wide jump between low and middle (75%, or about 5 sprockets), and (c) retaining very high gears that are feasible only for making a fast descent faster.
Swap in 3 new chainrings. This seems to raise similar concerns to item 2.