16 and 18 tooth freewheels on opposite sides of flipflop hub

FOAD Posts: 318
edited November 2009 in Workshop
I currently have an 18 tooth freewheel on my single speed road bike with a 48 chain ring, which given that the bike's main use is as a commuter with only a couple of lumps in the 12.5 mile each way route means I am losing out a bit on the flats and climbing the lumps with ease.

We are about to start doing a winter circuit which is 2.4 miles with alternating slight uphill/flat sprints on every other lap. I would like to go to 48 x 16 for the commute and the circuits and retain 48 x 18 for longer more hilly winter rides.

Is it possible to have 16 and 18 tooth freewheels on the flip-flop hub? I assume the biggest issue will be chain length - will just moving the rear wheel back a little in the drop-out sort the chain length, will a chain tensioner do it or is it just daft?

I haven't had chance to run this by my LBS as they are closed until tomorrow.


  • patchy
    patchy Posts: 779
    yes you can run two different freewheels.

    as you surmise, chain length will be your issue: do you have horizontal dropouts? If so, it should be easy to correct by sliding back and forth in the dropouts as you surmise. There's a small chance that it may affect your back brake however, so check that too.
    point your handlebars towards the heavens and sweat like you're in hell
  • FOAD
    FOAD Posts: 318
    Yeah it has a horizontal droput, but hadn't thought about the brake until you mentioned it.
  • John.T
    John.T Posts: 3,698
    It will drop the wheel back 1/2" and will bring the brake blocks closer to the tyre. If you adjust the blocks for the 16 cog you may find they are still OK for the 18.
  • andrew_s
    andrew_s Posts: 2,511
    2 teeth will move the rear axle by a quarter inch, not a half.
    Even easier to get the brakes set OK for both.
  • FOAD
    FOAD Posts: 318
    Thnka you all. :D