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What bb and crank setup is on the current bike, or are you shopping around for one now?
Pictures might help. I'm guessing shorter bb axle isn't an option?
I might have a some child specific cranks knocking about if that's a workable solution, I can have a look next week when I'm at the garage
psg1ben-
On the present bike is a Trek Dialled crank on a 118mm BB. It's actually a nicely designed crank except that the chainring is dished towards the BB. This utterly fucking stupid design decision means that the limiting factor is how close the chainring is to the chainstay. I could only get it to where it is by removing the inner plastic bashring/chainguide.
If the chainring was reversed (which I'm sorely tempted to try with a blowlamp and hammer) there's about 18mm between the end of each crank arm and the chainring, so I could go all the way down to a 103mm BB and reduce the Q factor by 15mm.
I also noticed that islabikes have narrower pedals with narrow spanner flats, which makes sense since they only need to be as wide as a pedal spanner.
To be fair, it's better than when I got the bike. At that point it had 170mm cranks on a 24" wheel bike, which seems daft.
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I am after some kid cranks for a couple of 650c projects if you do manage to find them
ffm
doubleodavey
Slight crosspost from the Q-factor thread: has anyone worked out a way of building a kid's mountain/hybrid bike with a decently narrow Q-factor without breaking the bank? I tried to get the stance as narrow as possible on mini-m's current bike but because of the daft crank design (only 157mm long but with unnecessary "flare") it ends up in the same ballpark as an adult hybrid i.e., 170-180mm). I've just measured up an Islabike Beinn and they get the q factordown to 146mm which is almost exactly the same as an adult road bike.
Of all the things that would induce me to buy an Islabike it's that they get this right. Once you've forked out for child-specific cranks (Hup), to achieve the same thing, you may as well buy an Islabike because its resale value will mean you end up spending roughly the same in the long run.