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  • Frame builder or aluminium welder in Worcestershire ?
  • Bit of an unusual job, as I’m sure they often are.
    I’ve bought a tandem frame with 145mm rear hub spacing.
    I intend to use a 135mm Rohloff hub.
    The easiest option I can come up with is to make two 5mm shims to the right shape and weld them to the inside faces of the drop outs.
    Then make another 5mm shim to go between the frame and caliper.

    Can anyone think of any reason why this wouldn’t work ?
    Any better ideas ?
    Who’s best to do it ? I’d rather deal with someone local in person than post the frame away.

    bencooper
    Free Member

    I recently made a custom spacer for a famous ex-STWer who was doing the same thing – it was a 10mm spacer on the left side of the hub, with a custom Speedbone.

    Saves modifying the frame though Rohloff don’t strictly approve.

    Though really bending in by 5mm either side isn’t a huge deal, if it was my bike I’d just bend the stays.

    fozzybear
    Free Member

    Can you not get some spacers made?
    Some 5mm steel spacers each side?

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    bencooper
    Free Member

    If it’s a QR hub, spacers would be a very bad idea – okay if it’s solid axle and there’s enough spare thread.

    I saw your work on Facebook, Ben.
    It was well done, but I’d rather modify the frame to suit a standard hub than modify the hub and build the wheel with a custom dish.
    Bending, or “cold setting” the frame would be the easiest option, but from what I’ve read from people trying to mix & match 130mm & 135mm road hubs, it’s not advised for aluminium frames.

    I can’t really see the point of 145mm hubs anyway. It looks like they are usually just a 135mm hub with a longer axle and spacers.
    If you’re not going to use the extra width to fit in a wider hub body and get a better angle on the spokes, then it’s actually weaker than a 135mm hub.

    singlespeedstu
    Full Member

    If you use a 5mm spacer either side it’ll alter the chain line by 5mm.
    Better as Ben said to use 10mm of spacing on the brake side and keep the chainline the same.

    Rohloff chain line, for all but 13t sprockets, is 54mm, which pretty much lines up with the outer ring of a triple chainset.
    Moving the chainline 5mm inwards will simply bring it in line with the middle ring.

    The only problem I can see with that, is that I was hoping to use a single sided drive to avoid having to buy tandem specific cranks.
    It means I would have to use the inner ring position for the primary drive, which then limits chainring size.
    I don’t know if that really is a problem though. Tandems traditionally use fairly big primary drive chainrings.
    Would a pair of steel 28t rings, with a shorter chain, be any heavier, or wear any quicker, than a pair of 42t aluminium rings.

    bencooper
    Free Member

    You could always have the primary drive off the big ring – I’ve seen that a few times…

    stevied
    Free Member

    If you need something making, drop me a message. I’m in Malvern and have access to some nice machining kit..

    mathewshotbolt
    Free Member

    145mm hubs make sense to me. you increase triangulation between drive and disc side spokes and bring the disc side tension up too.

    Ben, yes, using a triple leaves two options for the primary.

    Stevie, thanks, it’s always better to deal with someone who has an interest in the job. I’d rather have bike parts made by another cyclist.
    What about TIG welding though ?

    Mathew, 135mm & 145mm hubs seem to use the same body, they just vary the axle length and left hand spacers. Yes, I suppose shifting the rim 5mm towards the brake side would improve the spoke angle slightly.

    singlespeedstu
    Full Member

    I’ve seen a few MTB tandems use the outer position for the timing chain so that shouldn’t be a problem.

Viewing 12 posts - 1 through 12 (of 12 total)

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