Smaller front sprocket

The sprocket change has to do with the winter tire project. I`m not looking for any performance gains, only some more room for the rear tire. The problem is the gap between the swing and the tire. With the first tire (120/90-18) there was zero clearance with the mud guard attached.

The second rear tire (110/100-18) was almost good to go with no mods, but I wanted to make sure I got enough clearance so I spent the extra 12€ for a smaller sprocket.

The job itself is very easy. You need some slack for the chain, which requires loosening the rear wheel, but thats quicly done.

Original on the right and the new 13 tooth on the leftThe size difference is not that great

The gap should be enough now

UPDATE [Feb. 6th 2018]

Other than the added clearance I can’t really tell the difference with the smaller sprocket. Yes, it has been months between rides, but still. I did not test the top speed as the conditions were challenging enough as it is.


14 Comments Add yours

  1. Ferdinand pick says:

    I’ve thought alot about this ‘mod’. I know you didn’t do it for performance gains, but how is it? I assume your top end is compromised abit. How is the acceleration gain?

    I know It puts the speedo further out…


    1. 250rally says:

      Can,t test it yet as there is no snow. Running the spikes on asphalt will run them down fast.

      I assumed the speed came from the front wheel?


  2. Ferdinand pick says:

    Arh I see, spikes, cool!

    No it appears to take the speedo feed off the crank as changing sprockets defo affects it. You can buy a device to correct it though…


    1. 250rally says:

      Ah, good to know. I somehow assumed that the speed came from the front when the ABS measures the rotation speed anyway.


    2. six10kenbali says:

      Hi Ferdinand.
      I order a 13 tooth front online last week and picking up today.
      Whats the device or how can the sped do be corrected?


  3. aleks says:

    Why not just add in some chain links? Now your odometer will be off. And that’s bad.


    1. 250rally says:

      Don’t have the tools to add links. Odometer being off is trivial to me.


  4. Ferdinand pick says:

    Any thoughts on the sprocket change, how you finding it? . There has to be snow about now


    1. 250rally says:

      Yeah, one would think so, but no snow. Just cold. I’m going crazy waiting for a proper winter.


  5. wanasherpa says:

    I change the front-rear sprocket to 13-42 (from 14-40 the oem), get better performance not much playing the gear select to keep engine run well.


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