Thinking about getting some surly whirly cranks so I can run a 34/50 on a 73mm bottom bracket. I need roughly a 50mm chain line though and am not sure of how adjustable the chainline is between the spyders and chainrings. Does anyone have a whirly that could confirm if you can place the spyder adaptors (eg the 110bcd one) on either side of the 58 bcd spyder to change the chainline? or if a 110BCD spyder will fit to become an inner and middle ring chainline, or a middle and outer ring?
Aren’t they pretty new? Send Surly a message for sure.
34/50 chainrings on a 73mm BB shell? What freak of a bike are you making? Monster Monster Cross for sure.
I would have thought that you would have bugger all chance of manipulating the chainline on a external BB in a 73mm shell. But surely you’ll just use the 110bcd middle and outer rings as your two rings. If you’re running a Shimano SLX/XT front mech and rapidfire shifters you can manipulate the limit screws and lock-out one of the ‘clicks’ on the shifter to turn a triple mech into a double (as the SLX double mech is a compact for the inner two rings only - so that wouldn’t work with your proposed setup).
Hope this helps
EDIT: If you want more ability to mainpulate your chainline then I would recommend looking for a crankset that works with a JIS Square Taper BB (ie White Industries VBC or Sugino Alpinas) as you have more ability to manipulate the chainline by changing spindle lengths. (The other problem you may encounter is chainring clearance on the chainstay). The other bonus of Square Taper sealed bearing BBs is that their sealing is far far better than on External BBs - I go through twice as many BBs on my MTB as I would had it been a ST BB.
Thanks for the reply Dice. I’ve got a square taper with a 130BCD road crank on at the moment with 39/46, and I guess I can just buy a 110BCD with 34/50 square taper crank and off I go (the aim is to make it into a road bike in summer, cross bike in winter), but I kinda want to use external BB cups as they’re lighter and stiffer. It’s for my handmade bamboo cyclocross bike, which I stupidly built with a 73mm BB and 130mm rear spacing - hence the whacky chain line. Never again!
