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  1. #26
    tcs
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    Quote Originally Posted by jur View Post
    ...while I have theorised that the efficiency depends on the gear you're in, because of the way the ratios are created!
    If you're saying your theory is that the Second Law of Thermodynamics is, in fact, correct, I'll happily agree. If you're saying lubrication, quality of bearings, surface finishes, machine tolerances, tooth profiles, etc. make no difference to efficiency, I'll have to disagree.

    As I understand it, the Sturmey Archer 8(W)s have three sets of single stage planetary gears and make their ratios thus:

    1st gear: direct drive
    2nd gear: stage C (130%)
    3rd gear: stage A (148%)
    4th gear: stage B (169%)
    5th gear: stages A & C
    6th gear: stages B & C
    7th gear: stages A & B
    8th gear: stages A & B & C, 325% overall


    The Shimano 8s have four sets of planetaries and make their ratios as follows:

    1st gear: gear set one, 52%
    2nd gear: gear set one + gear set two, 52% x 122%
    3rd gear: gear set one + gear set three, 52% x 142%
    4th gear: gear set one + gear set four, 52% x 162%
    5th gear: direct drive
    6th gear: gear set two, 122%
    7th gear: gear set three, 142%
    8th gear: gear set four, 162%, 307% overall

    Best,
    tcs
    Last edited by tcs; 06-17-09 at 07:10 AM.
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  2. #27
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    Quote Originally Posted by ChiapasFixed View Post
    I generally find the Alfine to FEEL more efficient than the Nexus redband. Perhaps this is because it is quieter, smoother, or perhaps it has to do with the fact that the Nexus is spinning 24" wheels while the Alfine runs 16" ones. Or maybe the different geometries of the bikes have to do with it.
    In general, I am generally happier with the Alfine, and with the general feeling of the Tikit, generally.
    But this is, of course, a generalization...
    Doesn't your Joey run an extra 'spring loaded chain tensioner' that you Tikit doesn't need?

  3. #28
    hipster traffic dodger ChiapasFixed's Avatar
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    Quote Originally Posted by tcs View Post

    BTW, an Alfine SG-S501 and Nexus SG-8R36 are identical in internal construction.

    tcs
    ...but the Nexus is without disk brakes. in any case I was comparing the Alfine to my Nexus redband SG-8R25 which is alot noisier and I am sure less efficient. I did generally state that, in very general terms, this was nothing more than a generalization.

    On the other hand, it should be said that the way a drive train FEELS is a big component of how happy the rider will be with the bike, and thus how efficient it will be for getting said rider from A to B (because if i dont like the bike, i am less likely to ride it). This principle of hedonics may not have direct implications on absolute efficiency of the components, but would be an important factor in relative (or functional) efficiency.

    Quote Originally Posted by Brucemetras View Post
    Doesn't your Joey run an extra 'spring loaded chain tensioner' that you Tikit doesn't need?
    Yes, I actually run an Alfine chain tensioner with it, which would probably add both absolute and relative inneficiency to the system.
    IRO Mark V Pro, home made bamboo track bike, eddy merckx corsa extra, Airnimal Joey, UGADA Tikit

  4. #29
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    Any updates on your replace [w] hub tcs? Is it a reliable hub?

  5. #30
    tcs
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    The replacement hub arrived from Sturmey USA. They asked for the old one back, and sent a pre-paid postage label. I despoked the wheel (arrrrrrgggg) and packed the failed hub up and sent it off. I have the new hub, a rim and 36 spokes on my workbench, and that's as far as I've got.

    tcs
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  6. #31
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    Did they take long to send you the replacement? I know it is too late, but isn't the shell the same, therefore swapping the internals would be easier? Or you were playing it safe in case the shell was the problem? Please keep us posted on this.

  7. #32
    tcs
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    Quote Originally Posted by Joako View Post
    Did they take long to send you the replacement? I know it is too late, but isn't the shell the same, therefore swapping the internals would be easier? Or you were playing it safe in case the shell was the problem? Please keep us posted on this.
    They (well, really, he) took three weeks to answer my email, but the hub got sent out just a day or two later.

    AFAIK there are no instructions for (W) disassembly. Is it the same as the previous design? Probably. I don't have the 8-speed ball ring spanner, either (and yeah, I know there's a work around). Would Sturmey have still honored the warranty if I did a partial disassembly? Probably. Anyway, the wheel build was a real bodge job by a jackleg local wheelbuilder and I didn't mind the loss of it.

    tcs
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  8. #33
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    Pardon for going "slightly" off topic, but it's still about SA IGHs. It's probably the best place for me to ask because it seems all the IGH gurus are already tuned in one place.

    I'm new to IGHs and the only one I've had personal experience of is the SA 3 speed... and I'm slowly trying to get acquainted with others available - especially the SA 8 speed.

    My question relates to the shifting method. The SA 3speed I have has a mini-chain screwed into a hollow axle and is pulled by a side cable to activate shifting (which I don't particularly like). But I've since read about another shifting method where a cam or lever rotates beside the cog? But I can't seem to get any more specific info about it.

    Does any one know of a link that explains the details of an IGH that has this feature? The SA website has a few hubs like this but there's no tech sheet about them.

    Has anyone tried these? Are they better than the usual central side chain-pull method? Thanks!

    .
    Quote Originally Posted by dminor View Post
    Like clever mice, if there is a any crevice to exploit, a chain will find room to jump and derail; you can count on it.

  9. #34
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    The Sturmey 8 and 3-speed rotary series have the shift mechanism inboard of the chainstay.

    All other sturmey's use indicator chains.
    Internal Gear Hub Guru
    Currently owned hubs: Sachs Pentasport, SRAM P5 Drum, Sturmey SRF5-W , Sturmey XRD3
    Previously owned hubs: Shimano Nexus 8 speed, Sturmey AW 3 speed, Shimano 3 speed coaster, SRAM S7 Drum, Sturmey XRF8 8 speed
    Tested hubs: SRAM i-Motion 9 speed, Sturmey XRD5

  10. #35
    tcs
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    Sturmey Archer designed and patented the inboard shift cable in the early 1970s, but never put it in production. Shimano saw the idea for the good one it was and sat on the patent until it expired, then introduced their "revolutionary" seven speed hub with inboard rotary shift.

    Sturmey's three speed series with inboard rotary shift has been cataloged for the last several years but such a hub has never been spotted in the wild. There are indications that the hub is finally "in the pipeline".

    Of available three speeds, the SRAM iM3 is the only one to feature an inboard shift cable. With my Sturmey 8 out of service, I mounted an iM3 on the bike (a tikit) and I like this little hub better than the Sturmey SRF3 & AW, SRAM T3 and Shimano Nexus 3 hubs.

    tcs
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  11. #36
    rhm
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    Quote Originally Posted by Joako View Post
    Any updates on your replace [w] hub tcs? Is it a reliable hub?
    I have about 600 miles on my new [w] hub and have had no problems.

    Yet.

    Quote Originally Posted by tcs View Post
    ... AFAIK there are no instructions for (W) disassembly. Is it the same as the previous design? Probably....
    I suspect it's a pretty different design. The shift cable on the previous (non-W) pulled from the bottom, so (facing the hub from the right side) pulling the cable (to downshift) rotated the pulley counter-clockwise; the shift pulley on the newer (W) hub pulls from the top, so pulling the cable (to downshift) rotates the pulley clockwise. I'm not sure about the following, but I suspect it means a lot of the innards of the hub are different and some of them probably unscrew in the other direction from the earlier hub.

    Since my new hub was provided and installed in a competent bike shop, I'm planning to have them do all service on it, at least until I'm quite sure the warranty is used up.
    Last edited by rhm; 07-24-09 at 10:03 AM.

  12. #37
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    Update, please?

    Quote Originally Posted by tcs View Post
    I'll try to keep the community updated over the next several months as I put more miles on this hub.
    I'm grateful for your previous comments, and would be very interested in the offered update!

    Cheers

  13. #38
    tcs
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    My 2nd XRK8(W) has about 1200 miles on it now. It shifts smooth and FWIW 'feels' very free running. I haven't touched the adjustment since the cable bedded in, haven't missed a shift, haven't found a neutral and like it quite a lot.
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  14. #39
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    Quote Originally Posted by tcs View Post
    My 2nd XRK8(W) has about 1200 miles on it now. It shifts smooth and FWIW 'feels' very free running. I haven't touched the adjustment since the cable bedded in, haven't missed a shift, haven't found a neutral and like it quite a lot.
    Likewise, 1800 miles on my 2nd XRF8(W). Zero problems, no adjustment, and works great.

  15. #40
    Senior Member badmother's Avatar
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    Anybody know a source in Europe that sell the SA 8speed hub w 28 holes? Want one for my Brompton. SJS only sell the 36 hole hub.
    °Empty drums make a lot of noice... (Old Hungarian proverb).

  16. #41
    coprolite fietsbob's Avatar
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    Anybody know a source in Europe that sell the SA 8speed hub w 28 holes? Want one for my Brompton. SJS only sell the 36 hole hub.
    I believe that is all that is made..

    AFAIK its only the 3 speeds made for Brompton that are 28 hole..
    nothing but money to keep one from having the flanges plugged and re drilling a different hole pattern
    in a Machine shop with aluminum welding and a drill press facility ..

    a skip a hole pattern and a 24 spoke rim is another practical possibility,
    people have used 36 hole rims and hubs in groups of 6, and had 2 radial and 4 crossing spokes

    that idea, just leave out the radial spoke.

  17. #42
    tcs
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    Quote Originally Posted by fietsbob View Post
    I believe that is all that is made..

    AFAIK its only the 3 speeds made for Brompton that are 28 hole..
    Biketoolsetc in the USA offers to retail customers the 28 hole XRF8(W) and a 28 hole AW. In the EU, Old Bike Trader says they have them.
    HTH,
    tcs
    Last edited by tcs; 09-28-11 at 10:12 AM.
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  18. #43
    Senior Member kamtsa's Avatar
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    Quote Originally Posted by badmother View Post
    Anybody know a source in Europe that sell the SA 8speed hub w 28 holes? Want one for my Brompton. SJS only sell the 36 hole hub.
    You can get a Brompton kit here http://www.kinetics.org.uk/html/8-speed.shtml
    Happier than a camel on wednesday.

  19. #44
    Senior Member social suicide's Avatar
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    I've put close to 1000 miles on my R20 equiped with the XFR8-W. Only complaints are how noisy it is and the weight. 1800 gm! Been interested in the NuVinci 360 but where to put the extra cable?

  20. #45
    Senior Member badmother's Avatar
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    Thank you, I`ll see what I can get. I wanted the hub, not the kit. I built a 20" 36/28 wheel w a Nexus7 some years ago but would like to avoid tracking down the different spokelenghts. I can see from the pictures on two different "kits" plus the SA homepage that the 28 hole one is being used.
    °Empty drums make a lot of noice... (Old Hungarian proverb).

  21. #46
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by badmother View Post
    Thank you, I`ll see what I can get. I wanted the hub, not the kit. I built a 20" 36/28 wheel w a Nexus7 some years ago but would like to avoid tracking down the different spokelenghts. I can see from the pictures on two different "kits" plus the SA homepage that the 28 hole one is being used.
    You can get short spokes from Dans Comp for excellent prices.

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