Announcement

Collapse
No announcement yet.

Soma B-Side V.2 Belt Drive BBS02 750W/48V Custom Build

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #91
    Originally posted by MIKEinNC View Post
    Good afternoon Rider, I've been fascinated reading your posts on the belt drive conversion.
    I have a Soma B-Side (18.5") frame on order, and plan to follow in your footsteps, using the SA 3 speed IGH and a BBS02.
    I want to use the 55T x 24T sprocket combo, and wondered if you were able to use the same 118T belt when you changed ratios ?
    I'm thinking of using 26" wheels, with 2.5" Hookworm tires.
    Are there any particular negatives you can think of, in downsizing from 27.5", with the Soma frame, which I know is spec'd as 27.5 ? (Other than the less plush ride.)
    Any thoughts on 3 speed vs 5 speed IGH ease of installation and riding impressions, would also be appreciated.
    Thank you,
    Mike





    Hi Mike - if I may butt in till Rider comes back - here's the Gates Belt length calculator: https://www.gatescarbondrive.com/~/m...tor.xlsx?la=en and the currently available belt tooth counts.
    CDX - CenterTrack Belts (12mm wide)
    Teeth Length Part Number
    174 1914mm 11M-174T-12CTS
    168 1848mm 11M-168T-12CTS
    166 1826mm 11M-166T-12CTS
    158 1738mm 11M-158T-12CTS
    151 1661mm 11M-151T-12CTS
    143 1573mm 11M-143T-12CTS*
    137 1507mm 11M-137T-12CTS*
    132 1452mm 11M-132T-12CTS
    130 1430mm 11M-130T-12CTS
    128 1408mm 11M-128T-12CTS
    125 1375mm 11M-125T-12CTS
    122 1342mm 11M-122T-12CTS
    120 1320mm 11M-120T-12CTS
    118 1298mm 11M-118T-12CTS
    115 1265mm 11M-115T-12CTS
    113 1243mm 11M-113T-12CTS
    111 1221mm 11M-111T-12CTS
    108 1188mm 11M-108T-12CTS
    * Available Fall 2019

    I doubt you'd be lucky enough to reuse the belt after changing ratios, even after changing both belt pulleys. You'd have to run the calculator against your effective chain stay slider min/max, to see. Fiddling with belt drive ratios gets expensive, fast.

    On the wheel change, since the BBS motors cause a wide crank arm Q adding a motor PLUS dropping the tire diameter will raise pedal strike potential.

    On 3 speed vs 5 speed, I don't know of a 5-speed IGH with a cassette mount - is there one? The cassette mount is crucial to adjust the belt line - as is the related external bellcrank. Hub rotary shifter mechanisms takes up too much room and hurt the chain line.
    Last edited by ncmired; 10-18-2019, 10:41 AM.

    Comment


      #92
      Originally posted by MIKEinNC View Post
      Good afternoon Rider, I've been fascinated reading your posts on the belt drive conversion.
      I have a Soma B-Side (18.5") frame on order, and plan to follow in your footsteps, using the SA 3 speed IGH and a BBS02.
      I want to use the 55T x 24T sprocket combo, and wondered if you were able to use the same 118T belt when you changed ratios ?
      I'm thinking of using 26" wheels, with 2.5" Hookworm tires.
      Are there any particular negatives you can think of, in downsizing from 27.5", with the Soma frame, which I know is spec'd as 27.5 ? (Other than the less plush ride.)
      Any thoughts on 3 speed vs 5 speed IGH ease of installation and riding impressions, would also be appreciated.
      Thank you,
      Mike
      Hi Mike

      I was able to use the same belt with all the ratios I have tried to date on the B-Side and Wolverine stated in the thread, but I paired the front and rear belt rings with my existing belt length in mind. The Gates site has a belt length calculator you can use.

      The Soma B-Side seemed to have very good pedal to ground clearance, so I think you will be fine with 26x2.5 and stock Bafang 170mm cranks.

      I don’t think I would have ever sold this B-Side if it was an XL frame. I bought it before I knew what geometries fit me best. It a great frame and versital geometry.

      As for 3spd (33% gear gaps) vs. 5spd (25% gear gaps), I like the 33% gears gaps better for street use and 25% gear gaps better for off-road use. You get more range with the 5spd at the expense of shifting more. Not sure you will be able to align the belt on a 5spd without a custom made front belt ring. The great thing about the S-A CS-RK3 is the ability to adjust the belt line on the cassette and if you want to run a chain and derailleur you can setup a 21spd through 33spd.
      Last edited by Rider; 10-18-2019, 03:23 PM.
      MOVING BACK TO PEDAL...
      2020 Banshee Paradox V3 1x11 (pedal)
      2018 Soma Wolverine 3spd IGH Belt Drive (pedal)

      Comment


        #93
        Hi Rider, and ncrkd, thank you both for your responses.

        Also, thank you both for pointing out that the S-A CS-RK3 is the best choice because of the belt line adjustability it's cassette mount offers.
        I had registered that point, but somehow lost sight of it.

        Rider, I'm glad to hear that you were able to use the same belt with different pairs of cogs.
        I'd surmised that, if you added roughly the same number of teeth to one cog that you subtracted from the other cog, you could stay within the range of adjustability of the rear sliding dropouts.
        I'll use your experience as a much appreciated cross check for my measurements.

        When I asked the question about 26" wheels, I was actually wondering if that might cause a change in geometry, which could have a negative effect on the bike's handling.
        I'm not too concerned about the increased potential for pedal strikes, because I'll install shorter cranks along with the mid-drive.
        I've done that on two other BBSXX builds I've done, and I find it gives me a little more comfortable pedal cadence at higher speeds.
        It makes things a bit easier on my old knees.

        Thanks Again !
        Mike


        Comment

        Working...
        X