EBB not ideal for seat positioning. Gearing and Niner specific help sought- Mtbr.com
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  1. #1
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    EBB not ideal for seat positioning. Gearing and Niner specific help sought

    I had a great ride yesterday, I'm not a SS cult member yet, I think this is my first post on this side, but then I'm only about 100 miles in. I am a 29er cult member so we don't even have to talk about that.

    I like/really like my Sir9 so far but the EBB set-up wouldn't be my first choice if I did it again. I don't like how gearing changes effect the relationship between my seat position and bb. I guess once I get it all dialed it will be fine if I don't change gearing often and it's been 100% quiet for the last few rides.

    I'm still figuring out my gearing but didn't like the 32x20 (46.6gi) I ran yesterday in Pueblo. I always felt spun out and the climbs weren't an issue for cadence. I switched back to a 19t (49.1GI) which seems better in the neighborhood but don't like the new bb position further forward and up at about 7:45 on a clock.

    I'd like my bb as low as possible (6:00) for better cornering. It will take more time to figure out but think I'll end up somewhere in the 48-50 gear inch range. That means I can use a 32-19, 34-20 or 33-20. I was thinking of buying a 33t chainring to run 33-19 even though it may be a bit big at 50.6 GI. I'm hoping that since taking a tooth off the rear rotated the bb forward so adding one back on the front should swing it back down to where it was before. Does it work that way?

    Is there any way to figure out in advance of buying all the chainrings what cog/chainring combo to use so that my bb will be low and centered?
    Thanks,
    Art
    2 wheels

  2. #2
    Retro Grouch
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    It sounds like your eliminating the purpose of your EBB; you might as well epoxy the EBB in place and use a bottom bracket tensioner for the chain.
    Just one more rep and I get the toaster!

  3. #3
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    Use a magic gear calculator to get it close then maybe use a half-link.

  4. #4
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    You must be riding seated a lot.
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

  5. #5
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    As above re. the half-link - with one you should be able to get the EBB to the sort of position that you want. Personally speaking though, I don't find that it makes a whole lot of difference to my riding where the EBB ends up - how I feel on the day and what state my head is in makes a far bigger difference to me

    Analyse less, ride more ....

  6. #6
    CB2
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    Quote Originally Posted by Andy R
    As above re. the half-link - with one you should be able to get the EBB to the sort of position that you want. Personally speaking though, I don't find that it makes a whole lot of difference to my riding where the EBB ends up - how I feel on the day and what state my head is in makes a far bigger difference to me

    Analyse less, ride more ....
    My sediments exactly.
    Personally I've run from 32 x 17-20 on my Singular without changing the chain length or seat position and really haven't noticed too much of a difference. I do climb almost exclusively out of the saddle though.

  7. #7
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    Quote Originally Posted by Andy R
    As above re. the half-link - with one you should be able to get the EBB to the sort of position that you want. Personally speaking though, I don't find that it makes a whole lot of difference to my riding where the EBB ends up - how I feel on the day and what state my head is in makes a far bigger difference to me

    Analyse less, ride more ....
    Same here but the difference in EBB position will be more pronounced the shorter the rider. Personally I don't notice it at all but I'm over 6'. Maybe the OP has a short inseam?

    --Sparty
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  8. #8
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    Of course, if you are not using an EBB, then the linear adjustment of your sliders/trackend mounted wheel is going to change the wheelbase, slightly alter the effective headangle, and effect the weight distribution (metacentre?) of your bike....

    It's really a "princess and the pea in the bed" type problem.
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

  9. #9
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    Quote Originally Posted by Velobike
    It's really a "princess and the pea in the bed" type problem.
    Like most problems on mtbr.

  10. #10
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    artnshel: I can't imagine this being that big of a problem. Like most of the members above have posted, what they said, and get out of saddle and "pedal, damn it!" like the Niner adage. I also have an EBB on my 29er and your saddle adjustment fore/aft and height of seatpost can solve the issues you're having with the EBB. Stretching the chain over time causes more adjustment needs, but no tensioning system is free of drawbacks.The problems you're perceiving sounds like a roadie blaming his hardware for poor positioning in a race when he/she loses by 1/2 wheel length, not a "29er cult member."
    Creative Producer, Will of the Sun, Platform Pedal Shootout 1M+ views WoS

  11. #11
    master blaster
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    buy a new bike.
    Quote Originally Posted by ISuckAtRiding View Post
    The dude is like 120lbs, tops lol he can run any tires he wants without issues, i'm sure.

  12. #12
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    get a bike with track ends.

    they are still the best!!
    Ride & Smile

  13. #13
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    Thanks for the replies, I don't disagree with the princess and the pea assesment but that darn matteress still has lumps.

    I think a half link is a good suggestion.

    I do climb standing, it's the position for seated spinning I'm concerned about. I am tall but have had knee problems in the past and found that I need a steep seat angle/seat forward position to take care of my knees. Single speed is questionable for me anyway, all the physio's say spinning protects your knees better. To top it off I seem to like a big gear so I can still pedal to add speed down slight hills.

    I had an unbelievable SS ride a week ago and a marginal one two nights ago. So it goes.
    2 wheels

  14. #14
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    It sounds like you need a frame built to your measurements.
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

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