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  1. #1
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    Adding rear sprockets with an IGH.

    I wish Sheldon Brown were still around to ask, as I recall reading that he had done such.

    I'd like to be able to run three rear sprockets on on my Shimano 8speed hub.

    I know I could run a triple on the front, but:

    1-Rear derailleures work WAY better than front ones.
    2-I'd still need a tensioner in back which is most of the weight and pain of rear derailleur.
    3-Much easier to guard the chain/chainwheels with no FD.
    4-Less weight in small rear sprockets vs. big chainwheels, and FD+tensioner vs. RD

    Sheldon mentioned brazing I think (I can't find the article where he mentioned this.) It looks like the way the Shimano sprockets are dished/stamped I'd be asking for lots of warping if I got near them with a torch. I could probably press them back into truth, but maybe there is a better way?

    I have machine tools and all welding processes available. I can do this, just wondering if anyone can save me some pain in learning what works.

  2. #2
    Gear Hub fan
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    Sturmey Archer 3 and 5 speed hubs have a input driver setup which allows two cogs to be mounted on the input driver. Use dished cogs and two can be mounted with the dishes facing away from another allowing goiod separation between the teeth on the two sprockets.

    Shimano hubs do not have long enough input drivers to allow multiple sprockets and on the 7 and 8 speed hubs the shift cable attachment, the so called cassette joint, does nor allow room for two rear sprockets IMO much less three.

    You might ask in the below group linked to in my signature block if anyone has managed to do multiple sprockets with a Shimano hub but IIRC most success in this area has been with SA hubs. There even used to be commercial two and 3 sprocket conversions available for them.
    Last edited by tatfiend; 07-31-10 at 04:29 PM. Reason: correct typos
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

    Visit and join the Yahoo Geared Hub Bikes group for support and links.
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  3. #3
    cyclopath vik's Avatar
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    If you want to buy a ready to install solution there is the SRAM dual drive.

    http://www.sram.com/sram/trekking-co.../dual-drive-27
    safe riding - Vik
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  4. #4
    babylon by bike Standalone's Avatar
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    I've only read a few opinions on here, but I got the impression that IGH might not be up to the torque that happens with some Ute loads.

    I'd like to have a way to calculate gear inches for that SRAM dual drive, though. Looks interesting.
    The bicycle, the bicycle surely, should always be the vehicle of novelists and poets. Christopher Morley

  5. #5
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    I want the opposite of the SRAM setup. With the SRAM hybrid gearing you get all the chainline issues of traditional rear only derailleur systems, Most of your shifts will be moving the chain, and you can't shift (except between gross ranges) while stopped. The only advantage of this is that it is pretty efficient when in mid gear on the IGH.

    If you instead run only three rear cogs, then the chainline is either perfect or within +/- 1 cog spacing of perfect, you can shift while stopped, and most shifts are using the IGH which are pretty flawless.

    That guy that sells the Baekfiets and stoke monkeys up in the northwest built a big dummy up for his wife with a Nexus 8 and a Stoke Monkey. I emailed him a while back to ask how it was working out, but have not heard from him.

    Thanks for the tip tatfiend.

  6. #6
    cyclopath vik's Avatar
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    I don't see the room for what you propose on a Shimano 8spd IGH....I've got 3 of them and the spot you'd need to put the 3spd cassette is right where the hub shell and shifter cable goes in the hub..sounds like either it's impossible or a ton of work to get marginal gains over a dual front chainring setup. You could always wait for the 11 spd Shimano IGH to reach market.
    safe riding - Vik
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  7. #7
    cyclopath vik's Avatar
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    Quote Originally Posted by Standalone View Post
    I've only read a few opinions on here, but I got the impression that IGH might not be up to the torque that happens with some Ute loads.

    I'd like to have a way to calculate gear inches for that SRAM dual drive, though. Looks interesting.
    People are mtn biking and cargo biking happily with Alfine hubs so I'd be fine with using one in this application.
    safe riding - Vik
    VikApproved

  8. #8
    coprolite fietsbob's Avatar
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    There was a Replacement driver for British Made AW3 hubs on SJS UK site allowed 3 shimano cogs
    to be added via the spline external. might still be a few.

    back in the early 60's I bought a 3 cog driver that snapped on in place of the common 3 spline sturmey cog .

    I used the 1/8" chain , too. it was one block of steel machined and then tempered.


    Three speeds don't disengage the gears, just re apply the which one is driving and which one is driven ..

    want to calculate : http://sheldonbrown.com/gears/internal.html

    What you can do, is add a Schlumpf Speed Drive Crankset .
    it has a planetary overdrive of 1.6X the external cog/chainring combination.
    so you can have high range on top of the shimano hubs set.
    planetary overdrive add second ratio without shifting the chainring..

    and Ill offer a setup one of my friends Dad made up ,

    way back then , before JFK made that last drive thru Dallas.

    It used a second 3 speed
    it was mounted at the top of the rear triangle..
    dis assemble a steel hubshell 3 speed ,

    attach a cog to the spoke flange of the hub shell. as you say braze , {or Ive seen one laser cut with teeth and 18 holes and so can be pop-riveted onto a 36 hole hub**

    then the cranks will attach to the normal sprocket on the top hub, the second cog attached to the hubshell drives the hub in the wheel.

    Somewhere I thought I saw a hub manufactured like that, recently, with a second driven cog, ... as its a useful arrangement
    to drive a trike drive shaft to one of the wheels via a second, short, chain..
    Last edited by fietsbob; 07-31-10 at 01:37 PM.

  9. #9
    Senior member Dan Burkhart's Avatar
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    Quote Originally Posted by fietsbob View Post
    There was a Replacement driver for British Made AW3 hubs on SJS UK site allowed 3 shimano cogs
    to be added via the spline external. might still be a few.

    back in the early 60's I bought a 3 cog driver that snapped on in place of the common 3 spline sturmey cog .

    I used the 1/8" chain , too. it was one block of steel machined and then tempered.


    Three speeds don't disengage the gears, just re apply the which one is driving and which one is driven ..

    want to calculate : http://sheldonbrown.com/gears/internal.html

    What you can do, is add a Schlumpf Speed Drive Crankset .
    it has a planetary overdrive of 1.6X the external cog/chainring combination.
    so you can have high range on top of the shimano hubs set.
    planetary overdrive add second ratio without shifting the chainring..

    and Ill offer a setup one of my friends Dad made up ,

    way back then , before JFK made that last drive thru Dallas.

    It used a second 3 speed
    it was mounted at the top of the rear triangle..
    dis assemble a steel hubshell 3 speed ,

    attach a cog to the spoke flange of the hub shell. as you say braze , {or Ive seen one laser cut with teeth and 18 holes and so can be pop-riveted onto a 36 hole hub**

    then the cranks will attach to the normal sprocket on the top hub, the second cog attached to the hubshell drives the hub in the wheel.

    Somewhere I thought I saw a hub manufactured like that, recently, with a second driven cog, ... as its a useful arrangement
    to drive a trike drive shaft to one of the wheels via a second, short, chain..
    You mean like this.
    http://www.sturmey-archer.com/products/hubs/cid/6/id/44
    Gearhubs demystified and other cool stuff.


    Rule #12: The correct number of bikes to own is n+1

  10. #10
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    Quote Originally Posted by fietsbob View Post
    It used a second 3 speed
    it was mounted at the top of the rear triangle..
    dis assemble a steel hubshell 3 speed ,

    Hmmm <squeak of mental gears turning>

    I like the $chlumpf $peed drive well enough....just they price themselves out of my demographic. I mean how can you not like something named Smurf (I actually learned a lot of German watching "die Schlumpfen" on TV.)

  11. #11
    coprolite fietsbob's Avatar
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  12. #12
    Gear Hub fan
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    Quote Originally Posted by fietsbob View Post
    There was a Replacement driver for British Made AW3 hubs on SJS UK site allowed 3 shimano cogs
    to be added via the spline external. might still be a few.
    No longer in stock and I got the impression from the original listing near the end that they were NOS items that would not be available again once gone. Over the years there have been several commercial setups made to allow multiple input sprockets with SA IGH units so I would expect them to show up on ebay occasionally.
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

    Visit and join the Yahoo Geared Hub Bikes group for support and links.
    http://groups.yahoo.com/group/Geared_hub_bikes/

  13. #13
    Senior member Dan Burkhart's Avatar
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    Quote Originally Posted by tatfiend View Post
    No longer in stock and I got the impression from the original listing near the end that they were NOS items that would not be available again once gone. Over the years there have been several commercial setups made to allow multiple input sprockets with SA IGH units so I would expect them to show up on ebay occasionally.
    More vaporware from Sturmey Archer. http://sunrace-sturmeyarcher.blogspo...&max-results=7
    Scroll down to the CS-RF3
    No idea when it's going to hit our shores, not that I'm interested in it anyway. I had a couple of rental bikes with the Sram Dual Drive, and I was not terribly impressed.
    They seem to be most useful in small wheel recumbents and the like.
    Last edited by Dan Burkhart; 08-07-10 at 07:06 PM.
    Gearhubs demystified and other cool stuff.


    Rule #12: The correct number of bikes to own is n+1

  14. #14
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    Here is the Sheldon bike: http://sheldonbrown.org/otb.html
    1988 Miele Azsora

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