Sram Eagle for tandems
09-13-18, 01:07 PM
#26
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I used the Sheldon Brown gear calculator to analyze the spacing in gear inches of my 3x9 drivetrain. The way I typically shift only uses the largest 3 or 4 cogs in the smallest ring, the largest 6 or 7 in the middle, and all but the largest in the big ring. So the way I usually shift has gear inch spacing from lowest to highest gear that looks like:
20.6, 23.4, 27, 31, 35.1, 40.5, 45.8, 52.7, 61, 70.2, 82.6, 93.6, 108, 127.6.
There are slightly different ratios also available to me, but mostly redundant with these 14 steps.
Eagle with a 48 tooth chainring looks like 25.9, 30.9, 36, 40.5, 46.3, 50.4, 61.7, 72, 81, 92.6, 108, 129.6.
With 46T ring: 24.8, 29.6, 34.5, 38.8, 44.4, 51.8, 59.1, 69, 77.6, 88.7, 103.5, 124.2. If I were to switch, this is the ring I would probably choose, which would mean giving up a little on the high end and a bit more (~20%) on the low end, but otherwise the spacing would probably be acceptable.
20.6, 23.4, 27, 31, 35.1, 40.5, 45.8, 52.7, 61, 70.2, 82.6, 93.6, 108, 127.6.
There are slightly different ratios also available to me, but mostly redundant with these 14 steps.
Eagle with a 48 tooth chainring looks like 25.9, 30.9, 36, 40.5, 46.3, 50.4, 61.7, 72, 81, 92.6, 108, 129.6.
With 46T ring: 24.8, 29.6, 34.5, 38.8, 44.4, 51.8, 59.1, 69, 77.6, 88.7, 103.5, 124.2. If I were to switch, this is the ring I would probably choose, which would mean giving up a little on the high end and a bit more (~20%) on the low end, but otherwise the spacing would probably be acceptable.
09-13-18, 01:53 PM
#27
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Regarding total range (meaning difference between highest and lowest gears) of a 1X12, the numbers are pretty simple: just the ratio of the largest to smallest cog. For a 10-50 cassette, the range is 5. You can choose a larger chain ring that will give the desired high gear, or a smaller ring for a desired low gear, but the ratio is determined by the range of the cassette. Make sense?
Your own post further down in the thread shows that the range for the Eagle is not that much smaller than with a triple and a 26 inner ring.
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OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
09-13-18, 06:49 PM
#28
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i find this profound and unexpected.
09-13-18, 07:06 PM
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For performance riding on the road 1x is just to "gappy", especially at the top end. Going fast on flattish roads you want a reasonable selection of gears over 85". You spend quite a bit of time there and when working hard 15%+ jumps in gearing is the last thing you want.
09-13-18, 07:27 PM
#30
Senior Member
What the graph shows is while the general belief that a 1x would give an unacceptable too large gear ratio changes between gear changes, in actuality the change is actually no different than the smallest possible shift from ANY gear combination of a triple. What is the difference is the 1x does not offer the larger possible gear shifts from any gear combo of a triple.
i find this profound and unexpected.
09-14-18, 08:12 AM
#31
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For performance riding on the road 1x is just to "gappy", especially at the top end. Going fast on flattish roads you want a reasonable selection of gears over 85". You spend quite a bit of time there and when working hard 15%+ jumps in gearing is the last thing you want.
I now see that the Sram Eagle goes 10, 12, 14, 16, 18, 21, 24, 28, 32, 36, 42, 50
So the jump from 12t to 10t is almost 17%. My error.
Last edited by oldacura; 09-14-18 at 01:36 PM. Reason: new info
09-14-18, 09:37 AM
#32
Senior Member
There's a pretty handy tool for visually comparing the different drivetrain options discussed here (and nearly all others). Here's a link with it already setup to compare 44t x 10-50 12-speed to 53/39/30 x 11-34 9-speed.
Bicycle Gear Calculator
My tandem currently uses a 10-speed 11-42 cassette (usually with 52/34 chainrings), which has gaps very similar to the 12-speed 10-50 or 10-51 cassettes. It's manageable, but there are definitely times that I'd like closer spacing between the gears. Going to 1x12 would be less overall range and several ratios with wider gaps than our current setup.
Bicycle Gear Calculator
My tandem currently uses a 10-speed 11-42 cassette (usually with 52/34 chainrings), which has gaps very similar to the 12-speed 10-50 or 10-51 cassettes. It's manageable, but there are definitely times that I'd like closer spacing between the gears. Going to 1x12 would be less overall range and several ratios with wider gaps than our current setup.
09-14-18, 12:27 PM
#33
Full Member
There's a pretty handy tool for visually comparing the different drivetrain options discussed here (and nearly all others). Here's a link with it already setup to compare 44t x 10-50 12-speed to 53/39/30 x 11-34 9-speed.
Bicycle Gear Calculator
My tandem currently uses a 10-speed 11-42 cassette (usually with 52/34 chainrings), which has gaps very similar to the 12-speed 10-50 or 10-51 cassettes. It's manageable, but there are definitely times that I'd like closer spacing between the gears. Going to 1x12 would be less overall range and several ratios with wider gaps than our current setup.
Bicycle Gear Calculator
My tandem currently uses a 10-speed 11-42 cassette (usually with 52/34 chainrings), which has gaps very similar to the 12-speed 10-50 or 10-51 cassettes. It's manageable, but there are definitely times that I'd like closer spacing between the gears. Going to 1x12 would be less overall range and several ratios with wider gaps than our current setup.
09-17-18, 11:16 PM
#34
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Eagle sounds lovely to me for an upright road going tandem. I have a 24 speed Burley with slicks and it’s hungrier for a top and bottom gear than my newer 1x11 MTB (30 & 11-42). With aggressive tires and suspension maybe you don’t need the top end so much.
Eagle is available now at GX and NX level, it needn’t be expensive. The cassette for NX is a terrifying monstrosity suitable for keeping canopies from blowing away at swap meets but it does its job great.
Eagle is available now at GX and NX level, it needn’t be expensive. The cassette for NX is a terrifying monstrosity suitable for keeping canopies from blowing away at swap meets but it does its job great.
09-19-18, 09:16 AM
#35
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Is there a tandem crank that will accept the Sram Eagle drivearm? The Eagle crank requires a BB30, PF30, or PFGXP bottom bracket.
For the SRAM Eagle, the rear wheel must use the dedicated XD Driver freehub body to mount the 11 or 12sp cassette. The NX will fit on a regular splined freehub (eg. Shimano 11sp).
Although the NX is more affordable than the XX1 and GX, it has a smaller gear range and is much heavier. The PG-1230 cassette is 11-50T (rather than 10-50T), and weighs 615g. By comparison, the Shimano R8000 Ultegra (11-32T) weighs about 240g.
For the SRAM Eagle, the rear wheel must use the dedicated XD Driver freehub body to mount the 11 or 12sp cassette. The NX will fit on a regular splined freehub (eg. Shimano 11sp).
Although the NX is more affordable than the XX1 and GX, it has a smaller gear range and is much heavier. The PG-1230 cassette is 11-50T (rather than 10-50T), and weighs 615g. By comparison, the Shimano R8000 Ultegra (11-32T) weighs about 240g.
09-20-18, 01:37 AM
#36
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It's not really fair to compare the NX cassette to the Ultegra, I think. They're different animals. NX is equivalent to Deore level, two lower than XT/Ultegra. Shimano just left Deore stuck around y2010 tech level so there's no exact analogue. NX also has a steel chain ring - not especially trying to be light.
The Eagle chain rings look like they'll go on any crank that takes SRAM direct mount rings. If there isn't one of those for a tandem then it looks like Wolftooth claims nearly all their rings are Eagle compatible.
The Eagle chain rings look like they'll go on any crank that takes SRAM direct mount rings. If there isn't one of those for a tandem then it looks like Wolftooth claims nearly all their rings are Eagle compatible.
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05-20-20, 02:50 PM
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Does not work for Santana
Santana tandems use a 129mm spindle you get chainline right. I am now using the original posters idea and modifying. I will use the tripe crank and convert to double. Cheapest way to go. However, if someone wants to do this to a Santana, use an Easton 129mm spindle with Cinch crank. $400 but it should work.
