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  1. #1
    Frt Range, CO
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    SRAM i-Motion 9 users thread

    Here's a link to the shop manual (includes overhaul instructions and how to cut the shifter cable):
    http://www.sram.com/en/service/sram/...Y08_E_RevA.pdf


    I have a few questions:

    1.) The i-M9 hub manual says the primary gear ratio needs to be from 1.7 to 1.9. This gives a minimum gear ratio of 1.7 x 0.542 = 0.942 or a minimum gear inch of 24.4 inches with a 26 inch wheel and 27.3 with a 29 inch wheel. Since the final drive ratio includes the rear wheel size, why can't I run a 32T x 20T with a 29er wheel, giving a similar minimum gear inch to the 26er wheel (25 inch for the 29er vs 24 inch for the 26er)?

    2.) How tight should the cones be adjusted on the i-M9 hub? The old 3 speed Sturmey-Archer hub's bearing cones needed to be loose enough so the pedals don't turn while coasting. That always resulted in a slight side-to-side play in the wheel. Should the i-M9 hub's bearing cones be adjusted tight enough so that there's no side-to-side play in the hub? Or should it be like the old Sturmey-Archer hubs with a slight amount of play?

  2. #2
    Frt Range, CO
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    I'll answer

    I cut the cable down as per the instructions from the shop manual (see link above). Real easy and even if you don't cut it to exactly 82mm, no big deal. The 6th gear adjustment technique will account for any issues with cable length.

    Quote Originally Posted by pursuiter
    2.) How tight should the cones be adjusted on the i-M9 hub?...Should the i-M9 hub's bearing cones be adjusted tight enough so that there's no side-to-side play in the hub? Or should it be like the old Sturmey-Archer hubs with a slight amount of play?
    When I first installed the wheel on my bike, it wasn't loose. After ~100 miles I noticed the i-M9 hub had some play. I read the shop manual several time and decided this phase means no play:

    Quote Originally Posted by page 17 of shop manual
    Position the bearing in a play-free
    manner and tighten using nut (18).
    Wrench size 17 mm. Tightening torque
    15 20 Nm (133 177 in.lbs.).
    When I removed the rear wheel, I couldn't detect any play with my hands on the axles (could detect play when the wheel was installed on bike). I tighten the cone less than 1/8 turn (45 degrees) and re-installed the wheel. No play, the hub has noticeable slightly higher drag. I'll ride it for 20~30 miles and check again.

  3. #3
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    I'll have to check mine for play. It hasn't got many miles on it yet, and frankly, that wasn't even something I considered adjusting. But I'll bet my side-to-side play is less detectable because I'm using a 20" wheel.

    The cable length thing is annoying because Sram has us cut it with that plastic shroud / threaded adjustment cap thing in place. It's easy to forget before measuring and cutting, which I did the first time around. But the up side is that it's more difficult to forget before inserting the cable into the retainer and permanently deforming it with the set screw, which I've done before on my Rohloff bikes (they had a similar measurement procedure with an easy-to-forget piece).

    Thankfully, the i9 doesn't require the precise cable cut that the Speedhub requires, but I'd still be wary of straying too far: too short, and you may not be able to shift into gear one; too long, and you might find there's not enough adjustment left to align gear 6.

    I haven't given much thought to gearing. I ran the numbers when I first considered this hub back when it was first becoming available in Europe, calculated that it would work with the stock chainring that came with my bike, and haven't paid attention since. I'm pretty sure I'm running 52Tx whatever the stock cog size is, and am embarrassed to admit that I didn't read about the minimums in the manual, nor do I know exactly what it is. But it's working so far (i.e. I haven't broken it). I promise I'll look into this, for my own health and safety.


    How do you like yours so far? I'm thoroughly impressed with how quiet and smooth the i9 runs and shifts. I've got the coaster brake version on a Xootr Swift.
    speedub.nate
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  4. #4
    Frt Range, CO
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    Quote Originally Posted by Speedub.Nate
    ...I'm running 52Tx whatever the stock cog size is,
    I assume yours came with a 20T cog, 52/20=2.6, you're illegal

    With a 20" wheel your gearing makes sense, I wonder if the primary gear constraint is a big deal. I'm getting ready to go with a 32/20=1.6, illegal on the low side. With 32/20 that gives me a 25" gear on the low side, 85" on the high side, should be pretty good on an easy MTB course.

    How do you like yours so far? I'm thoroughly impressed with how quiet and smooth the i9 runs and shifts. I've got the coaster brake version on a Xootr Swift.
    I like it, the steps are well spaced, the hub is smooth and quiet. The shifts are smooth except I find the 3 to 4 and 6 to 7 upshifts to be a little rough, I assume it's part my technique, part the hub. I'm in the process of building up an Alfine wheel, I'll decide which one is best for me by riding both of them.

    I'm researching getting rid of derailieurs, hated 'em since 1972 when I bought a Schwinn 5 speed with my paper route money. Can't spell it, can't stand 'em. Ran cyclocross with a Sturmey Archer 4 speed hub in 1977, it was OK, just not enough gears.

  5. #5
    Frt Range, CO
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    Went for a 15 mile ride on the mean streets of Chicago last night, it came loose again. I'm going to adjust both sides of the hub and see if I can get this hub to not have play.

  6. #6
    Frt Range, CO
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    Quote Originally Posted by pursuiter
    2.) How tight should the cones be adjusted on the i-M9 hub? The old 3 speed Sturmey-Archer hub's bearing cones needed to be loose enough so the pedals don't turn while coasting. That always resulted in a slight side-to-side play in the wheel. Should the i-M9 hub's bearing cones be adjusted tight enough so that there's no side-to-side play in the hub? Or should it be like the old Sturmey-Archer hubs with a slight amount of play?
    OK, I figured out the issue, it's my error. When I installed the wheel, I was rotating the axle as far clockwise as the special axle washer allow. Nothing could be worse. As I was riding, the axle was rotating counter-clockwise was far as the special washers allowed. The rotation was loosening the axle bearing cones. Now I have the hub adjusted perfectly with no play, axle rotated fully counter-clockwise before tightinging. It takes a little back and forth between both axle nuts to do it right.
    Last edited by pursuiter; 08-17-2008 at 11:45 AM.

  7. #7
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    Quote Originally Posted by pursuiter
    1.) The i-M9 hub manual says the primary gear ratio needs to be from 1.7 to 1.9. This gives a minimum gear ratio of 1.7 x 0.542 = 0.942 or a minimum gear inch of 24.4 inches with a 26 inch wheel and 27.3 with a 29 inch wheel. Since the final drive ratio includes the rear wheel size, why can't I run a 32T x 20T with a 29er wheel, giving a similar minimum gear inch to the 26er wheel (25 inch for the 29er vs 24 inch for the 26er)?
    I decided to run a 32/20, factory recommendations be damned. The hub isn't really useful to me with the restriction, I want to run it off-road. So we'll see how it lasts. Just did an 18 mile ride with the 32/20, much more useful. On the road I used 8th gear for the first time, off road up a big hill I was standing in 1st (25inch gear) but I made it up

  8. #8
    Frt Range, CO
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    Update:
    Added axle/chain tuggers, much easier to set wheel position and chain tension. I consider them essential for horizontal dropouts and this hub (see 1st photo).

    The loose bearing issue is resolved. It is important to position the axle in the dropouts pre-loaded counter-clockwise. Large torque inputs to the hub (1st gear, up a hill, standing) will rotate the axle counter-clockwise, loosening the bear cone. The coaster brake version doesn't have this problem, the brake band prevents the hub from rotating. In the 2nd photo you can see the gear cable is tight up against the chainstay. That's where it'll end up when you grind up a hill in 1st gear.

    I gave up on the budget cranks, it's too hard to get the chain line just right. I purchased some FSA SS 32T w/bash plate from Jenson, $130, cheap.

    I've routed the gear cable low around the bb with zip ties. Easy and cheap, right now I'm too busy enjoying this ride, no time to pimp. The 4th photo also shows how I used the washers to get the desired 50mm chainline. Two washers on the chain side, one on the other side. The 73/68mm bb on a 68mm bike makes it easy to adjust. Since I'm already cheating on the gear ratio, I want the chainline to be correct/straight. Straight equals less stress on the hub.

    Overall impressions:
    I am loving the ease of an internal hub 1x9 rigid 29er MTB. I've put ~100 miles on this bike, about 60 off-road. If I have to stop to step over a log, no problem downshifting 3 gears to start out, just twist the shifter 3 clicks. As I pick up speed on a downhill I click a few up-shifts and engage my pedals with ease. I'm in the illegal zone with my 32x20 ratio, gives me a 27 inch low gear. Combine that with a rigid fork and 29er wheels, life is easy. My original plan was to use this bike as a commuter, oh well.
    Attached Images Attached Images

  9. #9
    Frt Range, CO
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    Quick note: the primary gear range is constrained from 1.7-1.9 on the coaster brake version, on the disc brake version there's no upper limit, just the lower limit of 1.7.
    Last edited by pursuiter; 09-08-2008 at 06:25 AM.

  10. #10
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    Quick update:
    - purchased a Jabberwocky frame and built up dedicated rigid.

    - changed the front chainring to 34T (Surly SS), decided to be legal on the ratio (34/20=1.7).

    - it's running very nice:
    I aligned the chainline within 0.2mm of perfect
    I adjusted the hub's bearing races on the bike, made it slightly loose, then tightened the bearing clearence until the play was just removed.
    Attached Images Attached Images

  11. #11
    Frt Range, CO
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    Well, I've given this hub a full chance, it's just not up to the stress of being on a mountain bike. The hub has water inside it from riding in wet/hosing it down, it's freezing up below 20*F. It makes horrible sounds while shifting under load...$450 is way too much for this hub/shifter, esp compared to an Alfine. Good luck finding parts like sprockets and dustcaps (dustcap needs to be replace EVERY time your pull the hub apart!). I'm moving it to a commuter bike, it needs a nice quiet life. I've installed an Alfine on my Jabberwocky, IMHO, it's the only low cost option for a mountain bike application.

  12. #12
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    Update:
    Put a few thousand miles on this hub, as a commuter hub, it's not too bad. I'm running 38x20 (1.90 primary ratio) and the even steps are nice. Don't notice the Alfine/Nexus's irregular steps in the dirt, it is irritating on the road.

    Added a few capfuls of ATF to the hub by removing the non-drive side cone and pouring it in. This made the shifting much nicer. Had some ATF weepage initially, now it's no worse than a Sturmey 3 speed hub.

    I'd consider road touring/camping with this hub, just not able to take the torque generated by going off-road with a 32x20.
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  13. #13
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    After lots of screwing around, here's how I adjust my im9:

    If the hub's cones are too tight the cranks rotate when coasting. If there's any hub play at the rim, it's too lose. This hub needs to be adjusted just right! If it's loose things sound very bad esp when shifting. After lots of trial and error, I found an adjustment technique that works.

    Key point is that the drive side locknut needs to be tighten before the non-drive side cone is adjusted. If the drive side locknut isn't tighten securely and the hub is adjusted, it will come loose again. The problem is that the drive side locknut backs off as the hub axle moves slightly from torquing the hub in overdrive, then underdrive, back and forth until the hub comes loose again. SRAM's non-slip IGH washers are cheap stamped units and the axle slips, Shimano's and Sturmey's are cast units, axle holds tight, SRAM needs to figure this out...

    Here's what I do:
    1.) Install hub in vise by holding axle flats in smooth jaws. Wheel is parallel with the ground, drive side down.
    2.) Loosen non-drive side locknut/cone 3-4 turns.
    3.) Flip hub over in vise (non-driveside locknut and cone installed but loose 3~4 turns) so drive side is up.
    4.) Tighten driveside locknut securely
    5.) flip hub over so driveside is down. (At this point you can remove the locknut and cone all the way and pour a few capfuls of ATF into the hub, esp if you can't overhual it at this time.)
    6.) adjust non-drive side locknut and cone until hub has no play. I progressively adjust the cone tighter until all play is gone. Not any extra, just until the play is gone.

  14. #14
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    Thanks Pursuiter, very valuable testing and review.
    2012 SC NOMADc
    2011 SC Driver8 BikePark Sled
    2012 Surly Pugsly Fatty Trail/Dogrunner

  15. #15
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    How can we have large dust caps, which must be replaced at every dismantling in accordance with the manual?

    I have not tried dismantling of this hub because I do not have the cap.

  16. #16
    Frt Range, CO
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    Quote Originally Posted by siegekim
    ...I have not tried dismantling of this hub because I do not have the cap.
    I've heard SRAM USA will send them to you if asked. Some have been able to remove the large dust cap without damaging it and are able to re-use it. I haven't opened mine up for the same reason.

  17. #17
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    Quote Originally Posted by pursuiter View Post
    Here's a link to the shop manual (includes overhaul instructions and how to cut the shifter cable):
    http://www.sram.com/en/service/sram/...Y08_E_RevA.pdf
    Sorry to resurrect an old thread, but the link above is now behind a firewall. Can someone link to an available copy of the manual, or PM me with one? I'm having trouble with my hub, and would like to be able to fix it myself rather than rely on a shop.

    Thanks!

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