Advertise on Bikeforums.net



User Tag List

Results 1 to 9 of 9
  1. #1
    Member kmcc2576's Avatar
    Join Date
    Oct 2008
    Location
    Chicago
    Posts
    46
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    chainline and spindle length

    So I just bought a Bianchi Pista off my neighbor and got a great deal because he never rides it. I put a BMX freewheel on it and noticed that it threw the chainline off by about 10mm.

    I was considering replacing the crankset anyway and noticed that the Sugino RD gives you a 45mm chainline with 103mm spindle length BB.

    Currently the bike has a 103mm BB with a crank that gives it a 42mm chainline. So the Sugino crankset alone would get me 2mm closer to the proper chainline.

    I noticed that the Sugino RD can also take a 107mm BB. So if i were to get a 107mm BB and the Sugino RD does this mean that It would move the chainring out a total of 7mm? Thereby giving me a much closer chainline, or is this completely convoluted logic?

    I've searched the forum quite a bit and haven't been able to find an answer, or if I have it has gone right over my head because I'm pretty new to bike mechanics in general. Any answer would be appreciated, thanks.

  2. #2
    Senior Member
    Join Date
    Jun 2008
    Posts
    148
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    no. just 2mm. (107-103)/2

  3. #3
    Senior Member
    Join Date
    Jun 2008
    Posts
    148
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    if its really 8mm difference (thats a lot) you need to double that...so 103+16=119mm with the RD will give you the right chainline. VERY odd by the way. Maybe look into different freewheels? or get an EXACT measurement.
    Last edited by bnhoang86; 10-21-08 at 12:29 AM.

  4. #4
    Member kmcc2576's Avatar
    Join Date
    Oct 2008
    Location
    Chicago
    Posts
    46
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by bnhoang86 View Post
    no. just 2mm. (107-103)/2
    O.k. I see now that a 107mm spindle would only give me 2mm. But, wouldn't the RD alone give me 3mm? for a total of 5mm?

    It's definitely pretty far off, at least 10mm. It's a regular shimano single-speed freewheel. I've seen that a lot of people here on the forums have used them on their pistas but I don't understand how they could maintain the same chainline since the freewheel is so much wider than the fixed cog. Pretty annoying.

  5. #5
    Senior Member
    Join Date
    Jun 2008
    Posts
    148
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    yup thats right. but i wouldnt deviate more than 3mm away from the chainline.

  6. #6
    Member kmcc2576's Avatar
    Join Date
    Oct 2008
    Location
    Chicago
    Posts
    46
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by bnhoang86 View Post
    yup thats right. but i wouldnt deviate more than 3mm away from the chainline.
    Alright, thanks for the help. maybe I can find a thinner freewheel in conjunction with the RD and BB.

  7. #7
    Junior Member petlor70's Avatar
    Join Date
    Oct 2008
    Location
    Stockholm, Sweden
    My Bikes
    Cervelo RS, Specialized Langster
    Posts
    8
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    This might be of help:
    http://www.sheldonbrown.com/chainline.html
    scroll down to the tables.
    If you know what hub you have you just add the hubs "chainline center to shoulder", with the freewheels "chainline from shoulder".
    Myself I have an IRO hub 36mm + shimano 1/8" freewheel 8.67mm= which gives me a chainline of 44.67. Almsot spot on for my Sugino RD.
    If this doesn't add up to reality for you, something might be incorrectly installed.

  8. #8
    Member kmcc2576's Avatar
    Join Date
    Oct 2008
    Location
    Chicago
    Posts
    46
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    My hub isn't listed. It has the Bianchi hub that comes stock w/ the Pista. I'm confident that everything is set-up right.

    It's a flip-flop hub and if I measure from the side of the hub to the center of the sprocket on the freewheel it is about 10mm longer than from the side of the hub to the center of the fixed gear on the other side. The problem is the thickness of the freewheel.
    Last edited by kmcc2576; 10-21-08 at 02:46 AM.

  9. #9
    Member kmcc2576's Avatar
    Join Date
    Oct 2008
    Location
    Chicago
    Posts
    46
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I just did some re-measuring. The freewheel is only about 3-4mm farther from the hub than the fixed cog but I did Sheldon Brown's technique for measuring chain line and the freewheel was about 7mm farther than the cog. I don't really know. I think I'm just too tired. I'll re-measure tomorrow.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •