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I recently picked up a children's bike from a council waste site. I'm going to refit it and I had a question about the compatibility of the gear shifter and chainset.

The shifter is a grip-shifter made by Saiguan (it looks very similar to the SRAM shifter). The left hand shifter has three settings and there are three rings on the chainset.

The chainset needs replacing but the gear shifters look like they are ok. However I can't locate a 3-ring chainset which has a crank-arm short enough for my child. Therefore I was going to replace with a 2-ring chainset.

So my question is are there any 2-ring chainsets compatible with a 3-gear shifter?

Hope this isn't a daft question, and thanks in advance for your input.

Chris

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    Is the front gripshift indexed or friction? They're often basically friction shifters. But note you can get a friction shifter for 5 bucks even if its indexed which will work with anything. – Batman Apr 22 '17 at 22:55
  • Hi. They're indexed i.e there is a click stop for each position? Are you saying that I can't use a 3-gear indexed shifter with a 2-ring chainset, but that I might be ok with a frictionless shifter? Thank you. – Chris Apr 23 '17 at 8:43
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Good work for using the council's eco-shop. Its a great way to find raw parts and donor bikes for projects.

The left shifter "should" work. but there's a risk the rider will overshift and go to the third/missing chainring.

You might get away with it by fiddling the limit screws on the FD, and set the FD so the "most slack" position on the shifter would be the missing chainring. That way rider overshifts, the limit screw holds the FD from going too far, but the shifter simply slacks off the wire, and nothing happens.

Give it a try and see what happens. At worst, its a trip back to the dump in a couple weeks for another donor bike. Or you can look for bike cooperatives in your area who may be able to help.

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    Or a trip online to pickup a friction thumb shifter for about 5 USD. – Batman Apr 23 '17 at 13:21
  • Thanks Criggie - I will give this a go. Even if it doesn't work it will give me a better feel for how to adjust the Front mech. Good idea on looking at co-operatives. There are a couple a few miles from me. – Chris Apr 23 '17 at 22:50
  • Thanks Batman. I'm going to give the frictionless a go as well I think. Even if the FD option works, I'm curious to see how the frictionless gear shifters work. Thank you. – Chris Apr 23 '17 at 22:52
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    @chris just a clarification - the two types are Indexed (there's a definite stop a the right place) and Friction (there is no clear stop when the chain is in the right place) Its up to the rider to get it in the correct spot and then friction holds the shifter in place. There is no such thing as a frictionless shifter. – Criggie Apr 24 '17 at 0:20

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