• Is there something I can measure on an old pair of cranks to work out whether they're JIS or ISO?

    They're an obscure White Industries by Sugino triple crankset that I can't find much information about on Sheldon, velobase, etc.

  • I think the flat section of the taper is shorter on ISO BBs, but I can’t remember the details. There’s a link to post by @mdcc_tester that myself and others have re-posted up thread that has a useful diagram which I think would help. Will update this post if I find it.

    Edit: https://www.lfgss.com/comments/8756147/

    Not sure what diagram I was remembering though. Plus I think the cranks would be the harder element to ID. Sorry, no help whatsoever!

  • Sounds like it doesn't matter according to that. I had been led to believe different from my googling thus far.

  • I have an ISO chainset on my track bike, which I’ve been using with a JIS bb for a while now. No issues whatsoever and the chainline is spot on according to my callipers. As long as you can avoid bottoming out an ISO bb spindle on JIS cranks, the only problem you should encounter is just finding the right spindle length.

  • Thinking about it for a while I realised WI make/made square taper bottom brackets. And those are JIS. Assuming that they would seek compatibility with their own BBS, I'm going to assume that's the taper.

    Now... To work out the spindle length........

  • ISO or JIS

    As long as you make sure the taper isn't too long or short, it doesn't matter:

    ISO BB is about ~2mm shorter than stated with a JIS crank

  • hi, new to the forum although been riding a long time. I have been riding this Langster since Feb this year and it's time to replace the BB.

    I'm struggling to remove it at the moment but using a tape measure it appears to be 68/103

    Can anyone confirm if this is correct and if so any recommended BB?

    Also if anyone knows which year model the Langster is that would be good too.

    https://www.instagram.com/p/BxWxj7ZhxOs/­

  • No one? I applied a bit of GT85 yesterday (run out of WD40) and left it overnight. That and my good friend Mr Leverage who helped thanks to using a socket wrench extender and it's out.

    BB is an RPM BB-7420 model. It's too rusty to see the size marked on it but my tape measure confirms BB shell is 68mm and axle width is 103 mm

  • I need advice.

    I have a 54cm Pre-Cursa, 170mm Andel fluted cranks, Un55 105mm BB and rear Quando hub (Varno build).

    Will it give me a useable chainline (OR, how do I find out how to calculate it before fitting it all and hoping for the best)?

    First bike build for 10 years so I have forgotten everything.

  • Are the cranks these ones? If so, it looks like you need a 110mm BB to get a chainline of 42mm (105mm will be 2.5mm out).

  • Balls. They are, yes.

    Is chainline being out by 2.5mm gonna be a big problem?

  • Probably fine, but a un55 in 110mm isn't going to set you back much so personally I'd get it right and not have to worry about bursting in to flames or being beset by a plague of skidding locusts (or whatever happens when chainline is out by too much).

  • Just double checked, it’s 107mm. At 1.5mm I’m gonna risk it! 😮
    Cheers for your help!

  • Hmm. Might not be the right place to post, but anyway. Chorus chainset (drive-side only) keeps working loose and I have to re-tighten the bolt after a couple of long-ish rides. Any ideas about where the problem might be? Have been riding this for over 18 months and has been fine, trouble started (I think) when I replace the outer ring as it was pretty worn out. Pics for context of the set up. Thanks in advance...


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  • I had the same problem ages ago, what I did was-
    Got 18" breaking bar with a 8mm hex driver in and tightened it up as tight as possible by hand, then put the pedal at 9 and the bar at 3 and then stood on both. I never had any reason to remove them before I sold the bike and they didn't come undone in the year after I did this.

  • Ah, right, cheers. Have a breaker and a big 1/2" drive socket with that hex. Was a bit nervous about overdoing things as I'm a right lump, but I'll give this a go.
    Might be over to the 'Uve bin Indra'd' thread later.

  • So I can't get a decent chainline for love not money on my track bike. In comparison to other cranksets I've got it seems this one (Sugino messenger I believe) is quite offset? Is it just me?


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  • Don’t worry Indra is live and well

  • What axle length should I look for in a bottom bracket meant to accomodate a crankset with two chain rings? It's a Campag Veloce or Chorus (don't remember which and the branding has worn off) crankset if that helps...

  • Wondering if anyone can help me with a BB query. I’m currently running a praxis t47 bb and m30 cranks installed. If I were to remove these cranks and install a regular bsa bottom bracket for some shimano cranks would the bb shell threading accept the new bb? Or is it a unique t47 thread?

    I’m aware of shims you can get for the t47 to accept a 24mm shimano crank, but I want the t47 and 30m cranks together on another bike.

    Thanks in advance

  • Hi can any one help me what type of BB tool I'll need to get this BB out so I can give it a service. Thanks


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  • Anyone know what the chainline measurements are for either side of the middle/outer spider on a hollowtech 2 mtb crankset are?

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Transmission database - for all your crank / bb / bottom bracket questions

Posted by Avatar for kowalski @kowalski

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