Swapping std and compact cranks in and out

[schwa86]

Folks--

Hoping for a little advice. Generally ride a std crank, but planning a trip to some pretty hilly terrain in Europe, and thinking I should use a compact crank. Have my eyes on a SRAM rival over in the classifieds.

A couple of questions:

1) On one one bike I have a SRAM Force 10 speed groupset. GXP BB. Assume I can just swap a compact in and out with some minor FD adjusting at most, correct?

2) On other bike, I have an old Ultegra 6500 9 speed groupset. If I swap in GXP BB and crank, will the 10 speed crank work with an otherwise 9 speed group? Seems from searching around that this should be ok (eg that 9 speed chains will work just fine with 10 speed cranks). Assume the adjusting may be a little more finicky here given the difft BB (haven't checked spindle lengths etc.)

Thanks as always!

[stien]

You should consider chain length when going back and forth. Just be careful. Some people don't even adjust the FD when they swap over.

[rice rocket]

What bothers you about the compact crank that makes you want to run a standard all the time when you're not in Europe?

I know, I know, the weaklings run compacts, but look at the numbers...

50x11 @ 90rpm = 32.0 mph
50x11 @ 120rpm = 42.7 mph
53x11 @ 90rpm = 33.9 mph
53x11 @ 120rpm = 45.2 mph

Are you constantly in field sprints and spinning out your 11T gear and you're getting beaten to the line by a couple inches?

I went compact and haven't looked back. Gaps between the chainrings are bigger (~ 4 shifts down in the rear to reach the same gear on a front upshift instead of 3), but I adapted pretty quick.

[Chance]

My suggestion was going to be the same as Rocket above except that if you prefer the closer ratios of standard chainrings and don't need the low climbing gears of a compact while in US, then get a 38T small ring for the compact cranks and change only that. No problems with front derailleur adjustments, chain length, rear derailleur capacity, or anything else. Just swap small ring and you should be good to go.

[130R]

I swap std's all the time

[Bob Loblaw]

You should be fine if you can get the front D squared away. You'll need t lower it a couple mm and check the adjustment.

As for chain length concerns, I would probably stay away from crosschaining the small/small combination while running the compact(a good idea in general anyway).

BL

[schwa86]

As always, thanks to everyone for their advice and suggestions -- very helpful.

[echappist]

alternatively, get the 52/36t set up

i agree with Rice Rocket above. My downhill speed on a particular section is ~42mph, and it actually takes me longer to get up to speed on the 52x11, not to mention that i prefer to spin at a higher rate on the downhills.