thinking bout an 8 spd sturmy

GoldenMotor.com

thegnu

New Member
Sep 15, 2011
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freedom pa
Hey all , my whole family has been loving the mb's I built but only with one complaint when we go out to ride the trike is too slow to keep up with me more specificaly its lacking hill climb power , I know the problem is the 3 spd , so i have been researching 8 spd hubs , the one I am leaning twards is the sturmy s80 8 spd does anyone have any practical experience with it ? an I cant seem to get any onfo on how to convert it to fit the trike , since it has the nexus 3 spd an dual chail rings .

Gary
 

Dan

Staff
May 25, 2008
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Moosylvania
Bump

I have never tried em so dunno. Reading around here, have heard good things Gary, but no personal experience.
 

The_Aleman

Active Member
Jul 31, 2008
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el People's Republik de Kalifornistan
The biggest problem with the 8-speed Sturmey is that gears 2-8 are all internally overdriven. 1st gear is 1:1 as opposed to 2nd gear for the 3-speed and 3rd gear for the 5-speed. This means that the 8-speed Sturmey wouldn't offer any hillclimbing benefits over the 3-speed you currently have unless you re-gear the cranks.

The Sturmey 3 and 5-speeds have proven themselves to be up to the task of motorvation. You might consider the 5 as it has 2 gears below 1:1.
 

16v4nrbrgr

Active Member
Mar 17, 2012
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North Bay
The SRF-3 and SRK-3 have 3rd gear as direct drive, and then 2nd and 1st are underdrive. When the indicator chain is relaxed, the clutch engages the planetary pins and the carrier drives the shell. I've had success with 1000watts electric in a 16" diameter wheel, but shock loading it offroad cracked the driver, which spread the freewheel cover, which jammed the clutch, which stuck it in between gears, which broke pawls. It seems everything is hunky dorey until it machine guns all the guts because of a sequence or combination of errors. The thing I don't like most is having to be gentle on throttle and not crack it wide open from a stop, which is horrible for it if you're in 1st. If you ride carefully it could last you years though, the gears looked okay.

I say go for anything without pawls. The Sturmey/Shimano cogs with three drive nubs like to fatigue shear and fail, so using a hub with a strong cog mounting is important. I went through 3 Sturmy 16t's with an 80t #25 bolted to it, hopefully that will be a thing of the past since I fixed the chainline which was off due to the hub not being adjustable in chain line if you've got a really wide swingarm. The Shimano sprockets look like they're less beefy than the Sturmey ones, but they might have better mettalurgy.