Schlumph drive with an Alfine 8 speed
01-03-11, 06:53 PM
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Schlumph drive with an Alfine 8 speed
Anybody running this combination? Are you using a mountain drive or speed drive? What are the cogs and the gear range?
I am working on a new build and am trying to get my head around the numbers...
Aaron
I am working on a new build and am trying to get my head around the numbers...
Aaron
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Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
01-03-11, 08:17 PM
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Last edited by BruceMetras; 01-03-11 at 10:52 PM.
01-03-11, 08:30 PM
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You can play around with it in the Sheldon Brown gear calculator if you figure out your chainring size, increase / reduce it by the ratio of the Schlumpf you want, and then input that number as the second chainring
I quite like the numbers that come out using a 2:1 ratio (44t chainring, 22t sprocket) into the Alfine with a speed drive and a 20x1.75" tire. Low of 19.7, high of 98.7. Pretty good for touring! You could tweak it towards speed, get some silly high gear inches, and still have respectably low hill climbing gears if you wanted.
The mountain drive reduces the ratio pretty severely, so unless you ran a huge chainring and a very small sprocket, i'd personally think that the reduced gear drive would be very hard on your internal gear hub. I'm not sure what the maximum input ratio on the Alfine 8 is unfortunately, but if you theoretically used a 52t chainring and a 16t sprocket, the input ratio on the reduced drive mode of the Schlumpf would still be 1.3:1, which is quite brutal. Some people exceed the input ratios on these hubs all the time, I think it depends on the user and the use. Plus, your lowest low gears would be around 13" on a 20x1.75" tire, which seems lower than what is typically really even useful. So overall, I personally think the mountain drive isn't too great in this case.
I quite like the numbers that come out using a 2:1 ratio (44t chainring, 22t sprocket) into the Alfine with a speed drive and a 20x1.75" tire. Low of 19.7, high of 98.7. Pretty good for touring! You could tweak it towards speed, get some silly high gear inches, and still have respectably low hill climbing gears if you wanted.
The mountain drive reduces the ratio pretty severely, so unless you ran a huge chainring and a very small sprocket, i'd personally think that the reduced gear drive would be very hard on your internal gear hub. I'm not sure what the maximum input ratio on the Alfine 8 is unfortunately, but if you theoretically used a 52t chainring and a 16t sprocket, the input ratio on the reduced drive mode of the Schlumpf would still be 1.3:1, which is quite brutal. Some people exceed the input ratios on these hubs all the time, I think it depends on the user and the use. Plus, your lowest low gears would be around 13" on a 20x1.75" tire, which seems lower than what is typically really even useful. So overall, I personally think the mountain drive isn't too great in this case.
01-03-11, 09:05 PM
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It's not an Alfine 8, but an AW3 sturmey archer, on my Brompton, 15t cog
Run a 54t ring on the MD crank, effectively a 21.6t low gear
theres a calculator thru their site https://www.schlumpf.ch/hp/berechnung...ltung_inch.htm
low gear high range,is followed by high gear in low range.
in my case .. 6 ratios .. 17 to 77"
Probably as Alfine has a bunch of reduction gears,
best to set up the external drive for low gear,
and then use the SD for overdrive.
Rohloff says use the overdrive type as they are 10 reduction ratios already.
so I'd think the Alfine would last longer if not over-torqued.
Run a 54t ring on the MD crank, effectively a 21.6t low gear
theres a calculator thru their site https://www.schlumpf.ch/hp/berechnung...ltung_inch.htm
low gear high range,is followed by high gear in low range.
in my case .. 6 ratios .. 17 to 77"
Probably as Alfine has a bunch of reduction gears,
best to set up the external drive for low gear,
and then use the SD for overdrive.
Rohloff says use the overdrive type as they are 10 reduction ratios already.
so I'd think the Alfine would last longer if not over-torqued.
Last edited by fietsbob; 01-03-11 at 09:10 PM.
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