I'm building up an old Terry bike and will likely pick up a NOS Shimano 600EX FC-6207 crankset. The corresponding bottom bracket for this crankset is the 116 mm BB-6207 cup and cone. However, given the ease of finding a new UN54 cartridge compared to sourcing a BB-6207, would I be able to use the crankset with a 115 mm cartridge? My bike has 68 mm diameter English threads.

2 Answers 2


Yes. Remember that 1mm of difference is 0.5mm difference on each side and you will not have to adjust your derailleur or gears to accommodate that. Sounds like you have done your homework already.

  • I ended up getting an Origin 8 116 mm cartridge BB. Just received it today, installed in a flash, and the crank looks perfect on it.
    – fideli
    Aug 31, 2011 at 6:00

But also be aware that offset is an important criterion. Cartridge offsets can vary from zero to 6-8 mm, IIRC, and you want to be within about 3mm or the cups won't be adjustable enough to maintain the proper chainline.

  • I haven't had a problem going back to the earliest cartridge BB's with just putting them in as a direct swap. I did find this though: blog.harriscyclery.com/relative-chainline-bottom-brackets - seems the 115 measures to as good as 116 anyway, if you round up rather than down... Aug 15, 2011 at 19:28
  • If I'm not mistaken, the BB-6207 has a symmetrical spindle so a symmetrical cartridge BB should be fine, no?
    – fideli
    Aug 16, 2011 at 6:00
  • 1
    I think the two most common offsets are 0 and 3mm. The 3mm is typically used on triple cranks. Aug 16, 2011 at 22:00

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