HammerSchmidt double-singlespeed gearing

Does the HammerSchmidt crankset work with a fixed wheel?

Nope. The cranks themselves freewheel, so the bike would no longer be fixed. If you put Hammerschmidt cranks on a fixed-gear, it will turn it into a freewheeling-enabled double-singlespeed bike.

But, yep. Nothing would be damaged, it just wouldn’t be a fixed wheel. And… you could run a superlight singlespeed rear wheel. A Shimano or White freewheel weighs a lot more than a 15t (or 12t Phil!) fixed cog.

Can I use this thing on a road bike?

Sure. With a little help from a framebuilder. You’d need the proper “ISCG 03 or ISCG 05 tabs” (whatever those are) retrofit to the bottom bracket.

The HammerSchmidt only has two chainring sizes available: 22t and 24t, which forces you to choose a very small cog if you want to use it on the road.

Road Gearing

I had thought the spread was too big, until I did the number-crunching. I like a wide range, because of where I like to ride. A normal gear for most times, and a low low for climbing.

  • 24/15 = 44″ and 70″ gears – I’d run this setup any day.
  • 24/14 = 47″ and 75″ gears – If it was a fixed drivetrain, it would be ideal.
  • 24/12 = 54″ and 87″ gears (for time trialing over mountain passes?)

Offroad XC (non-Downhill riding)

  • 22/15 = 40″ and 64″
  • 24/16 = 41″ and 65″

I calculated the low gears with Sheldon’s gear calculator, then multiplied by 1.65 to get the high gears.

I could have (should have) just chosen Schlumpf Speed Drive Bottom Bracket from the “internal gear hub” dropdown, since the multiplier is also 1.65. The numbers aren’t the same, but they’re close.

These gears and opinions are theoretical in nature – follow your own folly.
I would really like to hear about (and see) any road bikes set up with HammerSchmidt crankset. And if Truvativ wants me to test one, I think I can add the tabs…