thinking bout an 8 spd sturmy

Discussion in 'Motorized Bicycle General Discussion' started by thegnu, Oct 26, 2012.

  1. thegnu

    thegnu New Member

    Joined:
    Sep 15, 2011
    Messages:
    982
    Likes Received:
    0
    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
     
  2. Dan

    Dan Staff
    Staff Member

    Joined:
    May 25, 2008
    Messages:
    12,473
    Likes Received:
    49
    Bump

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

    thegnu New Member

    Joined:
    Sep 15, 2011
    Messages:
    982
    Likes Received:
    0
    GRRRRRR this is a problem . ah well time an thought will figure it out . thanks Dan
    Gary
     
  4. Mr. Minecraft

    Mr. Minecraft Visionary

    Joined:
    Jan 13, 2012
    Messages:
    349
    Likes Received:
    0
    I thought internal hub shifters break easily
     
  5. JonnyR

    JonnyR New Member

    Joined:
    May 13, 2012
    Messages:
    1,203
    Likes Received:
    0
    i herd good things about the SRAM i-motion internal hubs not much on the strumy 5 or 8 speeds
     
  6. The_Aleman

    The_Aleman New Member

    Joined:
    Jul 31, 2008
    Messages:
    2,658
    Likes Received:
    1
    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.
     
  7. 16v4nrbrgr

    16v4nrbrgr New Member

    Joined:
    Mar 17, 2012
    Messages:
    1,718
    Likes Received:
    1
    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.
     

Share This Page