Long time since I've posted (kids, work, etc), but I hope y'all can help me figure something out.
After getting tired of busting spokes commuting on my stock Rush Hour wheels, I'm building up a new wheelset: Surly hubs, Open Pro hoops, and DT spokes. On my current wheel (stock hubs, I assume Formula or something similar) I'm running an IRO cog.
Surly's manual for their hubs (
http://www.surlybikes.com/files/NewHubs_07.pdf) states, under the heading "Two reasons why our track hubs don’t always fit perfectly with other track cogs":
Our hubs have ISO standard threads: 1.375"x 24 TPI (34.92mm x 1.058mm). This threading was chosen due to its compatibility with other threads used on bicycle cogs. ISO threads fit English and Italian threads almost perfectly.
Fair enough. But the next sentence says:
It is important not to switch back and forth between cogs and/or hubs with different threads.
So does that mean that Surly does not endorse taking my IRO cog off the hub it is on now (with what are presumably English 1.370"x24 threads) and placing it on their hub? I cannot imagine that the Al threads on the hub have so distorted the steel threads on the cog that it will screw up the Surly hub, but then, I'm not a mechanical engineer.
Of course, Surly offers up:
Since we only control the quality and size tolerances of all our own products, we heartily recommend using Surly cogs and Surly lockrings with Surly Hubs to assure the best fit.
I could order a Surly cog (I already have two, but not in the 17t size I prefer to commute on), and sell the IRO cog, but that's a PITA if I don't have too. I could also just go for it, since I have two fixed sides on the hub, but it would suck to ruin half of a hub on a brand new $150+ wheel.
Thoughts (besides call Surly, which I might try)?