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-   -   Alfine 8 speed and two ring crank (https://www.bikeforums.net/commuting/350857-alfine-8-speed-two-ring-crank.html)

bikertrash 10-06-07 03:27 PM

Alfine 8 speed and two ring crank
 
Hello,
Has anyone checked out the Schwinn site and seen their World Adventure model? Anyway it has that new Alfine group. 8 speed internal hub, two chainring crank. Never seen that before. I figure this must be shimanos answer to the Rohloff. Not as pricey, but still have to deal with a derailer. I'm not sure if still running a front derailer is a good idea. I liked SRAM's concept of the 3X8 duodrive, but I guess that tends to break.Anyhow, as soon as someone gets this ride, let us know whatyou think. I'd offer a link, but don't knkow how to do that.

nashcommguy 10-06-07 08:19 PM

A friend of mine and I were talking about this very thing the other day. Single speed hub w/a tensioner and a front der w/2 chainrings, maybe a 50t and 40tx16. Also, in the same conversation we talked about a 3 sp bottom bracket/crank assembly w/a 7 or 8 speed internally geared hub. Seems we're a little late.:rolleyes:

ax0n 10-06-07 08:53 PM

Sheldon beat you to it (in a way, with an old Sturmey Archer 3 speed instead of an Alfine 8) and then some.

http://sheldonbrown.org/otb.html

nashcommguy 10-06-07 10:02 PM


Originally Posted by ax0n (Post 5406348)
Sheldon beat you to it (in a way, with an old Sturmey Archer 3 speed instead of an Alfine 8) and then some.

http://sheldonbrown.org/otb.html

What I should've said was a three speed 'internally geared' bb w/a single chainwheel coupled with a 7 or 8 speed hub w/a single cog. Thanks for having me clarify. Read the link to the SB article and though it's very innovative and funny he doesn't mention a bb w/ig. Everything is based on a triple chainring, 7 sp fw and a 3 sp SA hub. There must be something limiting about the type of torque/motion one applies at the cranks for what my friend and I came up with not to have been developed. Apologies to the OP for the thread drift.:o

climbhoser 10-06-07 10:51 PM


Originally Posted by nashcommguy (Post 5406618)
What I should've said was a three speed 'internally geared' bb w/a single chainwheel coupled with a 7 or 8 speed hub w/a single cog. Thanks for having me clarify. Read the link to the SB article and though it's very innovative and funny he doesn't mention a bb w/ig. Everything is based on a triple chainring, 7 sp fw and a 3 sp SA hub. There must be something limiting about the type of torque/motion one applies at the cranks for what my friend and I came up with not to have been developed. Apologies to the OP for the thread drift.:o


I've thought about the 3spd. BB and IGH option for some time. Not enough to really dig, but I agree that there must be some incompatability for us to not have seen it yet. Though I actually got the idea from someone else's thread drift many moons ago.

uprightbent 10-07-07 06:22 AM

Check out the new Jamis 08' Commuter. I have last year's 3.0 model with the Alfine group and love it. I think the new model is the 4.0?

It has 2 rings with a derailer and chain tensioner plus they added disk brakes. Sheldons shop gave the original bike last year great remarks and they stocked it as well. At $539 (for the 3.0) you'll have plenty leftover to add quality accessories and still remain under $1,000 for a nice, simple all weather ride.

grolby 10-07-07 10:44 AM


Originally Posted by nashcommguy (Post 5406618)
There must be something limiting about the type of torque/motion one applies at the cranks for what my friend and I came up with not to have been developed. Apologies to the OP for the thread drift.:o

A more likely reason that such a system hasn't been developed on a production bicycle is, as Sheldon Brown says, "nothing exceeds like excess." The technology exists (SRAM DualDrive 3x9, quad front rings, Schlumpf dual drive bottom bracket) to create a bicycle with 216 gears. But such a thing is outside the bounds of usefulness, as is Sheldon's tame-by-comparison 63-speed OTB. I think that we reached the level of covering the ground we needed with triple cranks and 7-speed cassettes and freewheels. More than that is certainly nice, but I think that, beyond 21 speeds, everything else is just gravy.

tcs 10-07-07 01:21 PM

The Shimano Nexus/Alfine 8 has goofy ratio steps between the gears. To half step this hub, one would have to use three chainwheels.

Starting with - arbitarily - a 700x32 and 23T cog. The three chainwheels could then be a 42T, 45T and 47T.

Gear progression would be:
1st ratio, 42/23 = 26"
1st ratio, 47/23 = 29"
2nd ratio, 42/23 = 32"
2nd ratio, 45/23 = 34"
3rd ratio, 42/23 = 37"
3rd ratio, 45/23 = 39.5"
4th ratio, 42/23 = 42"
4th ratio, 45/23 = 45"
5th ratio, 42/23 = 49"
5th ratio, 47/23 = 55"
6th ratio, 42/23 = 60"
6th ratio, 45/23 = 64.5"
7th ratio, 42/23 = 70"
7th ratio, 45/23 = 75"
8th ratio, 42/23 = 79"
8th ratio, 45/23 = 85"

TCS

JoebikerLa 10-07-07 05:04 PM

I upgraded to a red band nexus 8 from derailure gears with a close ratio cassette. It was a bit difficult getting used to some of the big jumps of the nexus, but I've adjusted. I live in a flat area, so finding one chain ring up front that gives me a comfortable cruse in 6th gear, or whatever gear you are happy with. I have plenty of speed range for the riding that I do.

I wrote all that to say that I don't need two chain rings, I just deal with the hub like it is. I do wish I had closer spacing though.


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