Have picked up a BMC Blast 20 for my 4 year old son. It has a twin chainring at the front end
It’s in as new condition, must’ve been ridden once or twice! What do I need to do to convert it to single chain ring at the front? New chain ring, new cassette with wider range? New chain? Any suggestion or help welcome.
Looking at a pic of it, chances are that the crank has fixed chainrings and it uses a freewheel rather than a cassette so you’re looking at a bit of a spend to get a marginal gain.
Evans sell kid sized single chainsets though that might do what you want but unless you’re desperate to save weight i would personally just leave it as it is or disable the front mech so it just runs on the small ring.
Your son is four, he’s probably not too concerned about drivetrain trends as long as it is a cool colour and it has a gear he can pedal in 🙂