Road Conversion Chainline ....help!

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  • I’ve searched round the different threads so apologies if this has come up:

    I have an old road frame that I want to convert to fixed, it has forward facing horizontal dropouts. Can I use a track bottom bracket and crank set to give me around 42mm chainline up front (e.g. a 107mm BB + Stronglight st-1000 ).
    (does a bottom bracket of that length usually fit into a road frame?)

    And then with the rear:
    Get a 130 Hub and using spacers line it up to around 42?

    Im asking this cos I may want to upgrade this frame in the future to a track frame so want to be able to move all the components across..
    Are 120 and 130 hubs the same size hub, just on different length axels with more spacers?
    i.e. could I replace the axel of a 130mm hub with a 120mm and remove some spacers
    and it would be identical to a 120mm hub, thus fitting into a new track frame.

    -would that mean that assuming that the bb fits in the new track frame, the only thing I would have to replace would be the axel to move all my componentry across to a track frame at a later date?

    -whats this whole ‘dishing’ thing that people mention to do with wheels/hubs?

    Sorry its a bit of a long one,
    Cheers for the help guys.
    ~Hybrid

  • Go and read this page by Sheldon Brown then come back with any questions you have. It's where I started when I built my first fixed and it remains the best reference page I've read.

  • yeah. read sheldon's site. it's got everything you could ever want to know.
    i've got a miche primato bb. you can adjust the chainline a little with it.

  • I reckon most track hubs, regardless of the spacing (110,120,130) will give a 42 mil chainline. Most hubs can be re-spaced either up or down with the addition of... er spacers funnily enough.

    If you get, say a sugino messenger crankset & bottom bracket, provided your BB shell is a relatively standard width, then say a system ex hub with a longer axle, you should get a pretty good chainline. But check sheldon because he knew more than me or indeed any other person on earth. (About bikes).

  • hybrid
    -whats this whole ‘dishing’ thing that people mention to do with wheels/hubs

    Bob's garage, over on fixed gear gallery, has some info on redishing and the like.

  • Hybrid:

    You shouldn't have to dish a track hub, unless it's single-sided fixed. For eg if you get a system ex/ambrosio/insert brand here hub (fixed/fixed), no dishing will be necessary. :)

    Also, the best thing to do is probably measure the length of the bottom bracket shell, seat tube diameter etc, because if it's an old frame there's a chance it will not conform to modern standards. I've been lucky, my current road conversion has 120 spacing, english threaded bb, 27.2 seatpost, so i could transfer all the bits from my (shitty) 'track' frame to the road frame without incident.

  • asm my current road conversion has 120 spacing, english threaded bb, 27.2 seatpost, so i could transfer all the bits from my (shitty) 'track' frame to the road frame without incident.

    'without incident'?

  • Outspoken Cycles have a 103mm Sugino BB for £20 that they specifically refer to as giving 42mm chainline with the ST1000

  • Make sure your BB spindle and crank have the same kind of square taper (either JIS/Shmiano or ISO/Campag). If your running JIS BB spndle and ISO cranks the arm will sit further out. Fit all that and measure it with some measuring calipers.

    Move onto the hub. Get a 120 track hub with a long enough axle (time to call a shop who stocks a few). Then get some spacers and you'll be fine.

    You don't need any special high-science or one of these...
    http://www.parklandscientific.com/VetDop­ProbeSphygHS-2.gif

  • pj (pj) [quote]asm my current road conversion has 120 spacing, english threaded bb, 27.2 seatpost, so i could transfer all the bits from my (shitty) 'track' frame to the road frame without incident.

    'without incident'?

    [/quote]

    It always has to come back to the angle grinder doesn't it pj (pj) (lake of darkness) (abaddon the despoiler of man, reaper of lost souls)

  • cheers guys!!

    @andyp

       I read sheldons chainline article last night but only after reading the treads for two long so the knowledge could not be absorbed...
    

    @asm

     I havent received the frame yet so I havent had chance to measure it up. the only thing I know is its an itallian thread and 130 spacing in the rear... I was just trying to get my head round what components Im gonna buy/how much I'm gonna spend.   obviously I'll hold off untill I've measured the length of the bb shell. cheers for the advice!
    

    @miro_o

    yea cheers, gotta remember the taper type I'm going for. and good idea about calling up some shops (i've stuck to the internet so far) I understand that you can contact Goldtec to get longer axels from them.
    
  • Italian thread will make switching the bits more difficult - it'll limit you to italian frames, and even more than that because not all italian frames use italian threaded bottom brackets. Also they aren't reverse threaded like ISO/british threaded bbs.

  • yea I didnt mention that to avoid complicating things further,
    I am aware that if I change frames I most definitely will have to change bottom brackets ....
    ....but hypothetically If I have for example an Italian bb (60mm diameter) with a JSP taper of 103mm length,
    ....then surely if I fitted a track frame with a British bb (58mm diameter) with a JSP taper of 103mm length... then I should get the same result???

    Oh.. I didnt know Italian bbs arent reverse threaded.. thanks for the heads up!

  • Yep, same thread direction on both sides. with a decent BB it's not an issue though - won't unscrew or anything :)

    Yep, you'll get the same chainline with those 2 bbs - just wanted to make sure you knew. I've had no end of trouble with compatibility between frames in the past, there's always something you forget about.

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Road Conversion Chainline ....help!

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