Dear Matt,

I am looking at new bikes for my six-year-old daughter. She is used to cycling both on her own and for longer distances on the back of a tandem. When should she be starting to use a bike with gears?

Judith Berry, via email

Your daughter sounds advanced, so I'm sure she could use gears on her next bike. The problem is that most children's bikes are marketed on two principles: price and features, so that not very discriminating parents think they are getting a lot for their money. The result is that kids end up on bikes with heavy suspension that they don't need and cheap components that don't work. No wonder they soon stop riding.

So go to a dealer with a different philosophy - such as Isla Rowntree (a top cyclocross rider, incidentally), who has developed a range of good-quality children's bikes with a sensible level of kit at a decent price. Your daughter is probably ready for a bike with 20in wheels and six gears, unless she's big for her age, in which case she might suit a 24in-wheeled, eight-speed model. (See www.islabikes.co.uk)

Send your cycling queries to bike.doctor@theguardian.com