geneman
07-12-04, 08:45 PM
What's the story behind this? What sort of advantage are they supposed to provide? What are the downsides?
just curious.
-mark
just curious.
-mark
Road Cycling - compact drive trains?
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.View Full Version : compact drive trains?
MichaelW
07-13-04, 11:19 AM
For the same gear ratio, you use a smaller chainring and rear cog.
Pros: less weight, easier to get lower gears
Cons: limit to largest gear, faster rate of wear, ring-to-ring distance does not always work with indexed roadie shifters, there is a very small decrease in efficiency with smaller cogs, but its hardly measurable.
Most tourists use MTB style chainsets to get lower gears.
Pros: less weight, easier to get lower gears
Cons: limit to largest gear, faster rate of wear, ring-to-ring distance does not always work with indexed roadie shifters, there is a very small decrease in efficiency with smaller cogs, but its hardly measurable.
Most tourists use MTB style chainsets to get lower gears.
khackney
07-13-04, 12:51 PM
You can get almost the range of a triple crank using a compact double. So, you end up with a low granny if you live in the hills and a usable top end for all but the most screaming downhill runs. Quicker front shifting than a triple. Campy is due out with their versions along with FSA. I don't know what is planned by Shimano.
fogrider
07-13-04, 02:45 PM
I'm using a 48x34 chainrings with 11x25 rear cogs. I live in san francisco and my house is at an elevation of about 800 feet above sea level. For years I have made do with a 53x39 and 12x25, but the compact cranks allows me to spin faster up the hills and the shifting has been great. I could not find a 11x25 cog set but I took a 11x23 and put it together with my 12x25. I spin out with a 48x12, but the 48x11 has been great! It's almost the same as a 52x12 and I'm able to pedal at 44 mph. FSA sells a 50x34, the 50 produces a 112.5 gear inches, 48x11 produces a 117.8 gear inches, 53x12 produces 119.25 gear inches.
The advantage to the lower gearing is that I'm able to stay in the big chainring on most of the flats and rolling hills. :)
I'm going to have one bike with a compact set up for the hills, one standard double with 27 cog in the rear, and a commuter bike also with a 53x27.
The advantage to the lower gearing is that I'm able to stay in the big chainring on most of the flats and rolling hills. :)
I'm going to have one bike with a compact set up for the hills, one standard double with 27 cog in the rear, and a commuter bike also with a 53x27.
Murrays
07-13-04, 07:39 PM
Cons: limit to largest gear, faster rate of wear,
I was thinking that I would wear my gears faster, but I think i would spend a lot more time in my big chainring (I'm in my little ring most of the time since I have a comfortable cadence over 100). So I think it's possible I would wear out my rings and cogs less quickly.
-murray
I was thinking that I would wear my gears faster, but I think i would spend a lot more time in my big chainring (I'm in my little ring most of the time since I have a comfortable cadence over 100). So I think it's possible I would wear out my rings and cogs less quickly.
-murray