I have a 90s era Cannondale Killer V 900. I believe it has the Headshock fork with the shock directly below the headset.

I am converting the bike to an electric commuter. I have a few other bikes - just don't like to get to work sweaty.

The ebike motor kicks out so much torque that a steel fork is recommended. I am a noob on bike maintenance and it's tough to tell much info on the boards.

Based on what I have gathered I can get a 1.5 to 1 1/8 conversion piece and get a steel fork.

Can someone confirm this? I'm also not sure on if I get threadless or threaded and if any differences exist in lengths? (i.e. do I need some spacers or something else.)

  • If the motor puts out so much torque they recommend a steel fork then a 90's aluminum frame is not a good choice. So you have a few bikes? Does not make this a good project bike for conversion to electric.
    – paparazzo
    Commented Mar 27, 2015 at 18:22
  • 1
    Unless the motor is on the front wheel, the comment about steel forks and torque doesn't make a lot of sense to me. Where did this advice come from? Commented Mar 27, 2015 at 18:35
  • @FredtheMagicWonderDog Torque on the crank flexes the whole bike down to the wheels.
    – paparazzo
    Commented Mar 27, 2015 at 18:40
  • Yes the motor is on the front wheel. As aluminum breaks - the torque on the fork can snap the wheel mount. So its just at the torque point. You can put on torque arms - but does not entirely eliminate the issue. Steel bends and it stronger. The same issues exists if I put on a rear motor (both the frame and fork are aluminum) - so if I put Commented Mar 27, 2015 at 18:48
  • The same issues exists for a rear wheel as the frame is aluminum - you can put in some steel plates to reinforce the wheel mounts - -but in the rear there is limited room to do this - -so its much simpler to put the motor in front. Commented Mar 27, 2015 at 18:49

1 Answer 1


Yes, you can use a 1 1/8" fork with a 1 1/2" frame. I did it on one of my bikes. You just have to get a special "reducer" headset. It doesn't look goofy at all - you can't even tell unless you look closely.

You'll have to get a threadless fork. Nobody makes reducer headsets for threaded forks.

Most new forks come with an un-cut steering tube - that means it's a few inches longer than most people need, and you have to cut it to the right length.

Make sure that the crown-to-axle distance is approximately the same as your old fork. If not, it'll change the bike's handling characteristics, maybe drastically.

  • Thx much - will check it out Commented Mar 27, 2015 at 20:10
  • @TomMcCarthy be careful because the Cannondale HeadShok1.5" is not the same as other 1.5". There are adaptors specifically for this that either allow the frame to take a 1 1/8" headset or others that allow the existing bearings to be used. I have used both types and I think if you can use the headshok bearings you will be better off, and the cannondale kit is still in production. Search part KP058
    – Noise
    Commented Jul 27, 2021 at 20:00
  • @TomMcCarthy qwertycycles.co.uk/products/…
    – Noise
    Commented Jul 27, 2021 at 20:01

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