Nexus + double crankset?
#1
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Nexus + double crankset?
Hello,
Some people I know have a couple of Dahon folders that have a Nexus 7 gear hub.
With a 245% range, those bikes are fine for small rides in relatively flat areas, but don't have enough gear range for travelling.
I have a couple of questions:
Thank you.
Some people I know have a couple of Dahon folders that have a Nexus 7 gear hub.
With a 245% range, those bikes are fine for small rides in relatively flat areas, but don't have enough gear range for travelling.
I have a couple of questions:
- I read that some people installed a double crankset for use with Nexus/Alfine gear hubs, although the ratio blows away Shimano's torque limitation: How reliable is that solution in practice?
- How easy is it to replace a Nexus 7 for a Nexus/Alfine 8?
Thank you.
Last edited by Winfried; 06-04-19 at 07:13 AM.
#2
Banned
2 pulley chain tensioner and you can give it a try.. they're like a short cage RD
make the low gear within the range acceptable for the hub , big ring higher than that will be fine..
I've only used the big reduction gear 2 speed crank on my 3 speed.
It does not use an internal gear change, just changes the application..
the gears themselves never shift, only the pawls ..
(My Brompton, with a mountain drive crank.. ) 54: 15
Rohloff * gives you a minimum but higher gears are said to me fine ..
so the hub in my 20" wheel with a 53t chainring is better by their suggestions,
than the same hub in a 26" wheel with a 38t chainring.
* I have the manual for that, not for the Nexus, but you can find the one for your hub, online ...
Order a pre built wheel from your favorite bike shop, through their wholesaler is simplest..
maybe go for their 11 speed and that will be wide enough a range?
....
make the low gear within the range acceptable for the hub , big ring higher than that will be fine..
I've only used the big reduction gear 2 speed crank on my 3 speed.
It does not use an internal gear change, just changes the application..
the gears themselves never shift, only the pawls ..
(My Brompton, with a mountain drive crank.. ) 54: 15
Rohloff * gives you a minimum but higher gears are said to me fine ..
so the hub in my 20" wheel with a 53t chainring is better by their suggestions,
than the same hub in a 26" wheel with a 38t chainring.
* I have the manual for that, not for the Nexus, but you can find the one for your hub, online ...
How easy is it to replace a Nexus 7 for a Nexus/Alfine 8?
maybe go for their 11 speed and that will be wide enough a range?
....
Last edited by fietsbob; 06-05-19 at 12:41 PM.
#3
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I might stick an eight-speed Shimano Nexus hub into a Brompton.
Apparently, cogs for that hub have a three-tab spline.
However, the smallest cog is supposed to be 16T, which might rub against the chain stay.
I notice…
1. a 14T cog on eBay
2. Brompton cogs from Sturmey-Archer have a three-tab spline.
Do you think I could use that 13T cog instead?
Thank you.
--
Edit: I notice some cogs are for an 1 1/8" chain, while others are for a 3/32" chain.
Does it really make a difference when used with a gear hub, ie. a single cog on the hub — I might add a double crankset in the front later, though?
Apparently, cogs for that hub have a three-tab spline.
However, the smallest cog is supposed to be 16T, which might rub against the chain stay.
I notice…
1. a 14T cog on eBay
2. Brompton cogs from Sturmey-Archer have a three-tab spline.
Do you think I could use that 13T cog instead?
Thank you.
--
Edit: I notice some cogs are for an 1 1/8" chain, while others are for a 3/32" chain.
Does it really make a difference when used with a gear hub, ie. a single cog on the hub — I might add a double crankset in the front later, though?
Last edited by Winfried; 02-10-21 at 02:57 PM.
#4
Schwinnasaur
I can not answer question knowledgeably as I have not done this. I would stay with the 3/32" stock chain just because that suits chain wheel and the derailleur/tensioner.. I am curious as to how you are going spread the chain stays? I seems scary to me with such short says. 112 mm to 135 mm, I think.
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I had it done by an ol' timer
But since it was a first, until I have a Nexus wheel in there, I can't be sure it works — chainline, tire and/or spokes rubbing against the frame, front wheel not hooked right onto the frame, possibly other issues I can't think of at this time.
--
Edit: "Shimano Nexus and Alfine cogs will work with either 1/8" or 3/32" chains" (source)
But since it was a first, until I have a Nexus wheel in there, I can't be sure it works — chainline, tire and/or spokes rubbing against the frame, front wheel not hooked right onto the frame, possibly other issues I can't think of at this time.
--
Edit: "Shimano Nexus and Alfine cogs will work with either 1/8" or 3/32" chains" (source)
Last edited by Winfried; 02-10-21 at 04:54 PM.
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The Sturmey Archer shown there is also a flat sprocket, while the Shimano is dished, which might be an important consideration if you are worried about the chain hitting the chain stay. I have seen both flat and dished sprockets on my Romets when I buy them, and the dished one's have noticeable chain rub on one side of the sprocket.
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Using the 8L+8R blue+green anti-rotation washers, I notice the pulley arm of the Alfine 11 cassette joint is way too low when fit inside a Brompton rear triangle.
Would one of the other pairs (5, 6, 7) solve the issue?
Would one of the other pairs (5, 6, 7) solve the issue?
#9
Schwinnasaur
It looks like you bent the drop outs rather than separating the stays (which would be scary, to me).
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