Originally Posted by
jockstick
After a lot of deliberation, I think I'll go with the following for extra low gearing as I want to take this bike touring (I wish I could post links below):
- 50-34 compact crankset
- 13-28 cassette
It's about the same price as swapping out the rear derailleur (sjscycles has a really good price on the crankset) but this way I also get a fresh set of chainrings and won't risk getting a dud used derailleur or have to replace my chain to a 9 speed (just replaced it).
That 34-28 low gear will be a lot lower than your current 39-23. 40% lower! That's about 3-4 rear shifts, depending on tooth counts.
But the 34F-28R still just the same as many new 11-speed road bikes. But even my triple's approximately 1:1 low gearing, 30F-29R, isn't low enough for steep climbs on rough roads or a big load. My triple is great for all-day rides carrying the day's supplies -- the middle 39 chainring is perfect for flat to rolling terrain, and the 30 small chainring is pretty good on climbs. I'd like even smaller, though, a 28 or 26 small chainring.
For touring, carrying a fairly heavy load up a moderate to steep grade will be hard work with a 34-28. It should work okay for lightweight loads.
Lower gearing
Can you switch to a
triple crankset? That would really help.
Or some riders are getting
small cranksets, like a 30-46. They tend to be expensive, though.
EDIT--
I don't know much about square taper cranksets or 7-speed compatibility, but this one from sjscycles is
110 / 74 sized. It should fit 30 & 46 chainrings.
Thorn crankset