Last week I gave up my Sunday club run to go for a ramble with Sue in the Spring sunshine. This was a round trip from Henley in Arden to Preston Bagot following a route in Des Wright's Country Walks in Warwickshire and Worcestershire Meridian Books. Coming back to the car park I saw a young boy proudly trying out what was clearly his first two wheeler, a very nice looking junior BMX. He was with mum and dad and the family dog and getting on very well. Except that the forks were the wrong way round, so more than inexperience was explaining his slightly unstable style! The brakes were behind the fork crown (OK on an aerodynamic time trial bike perhaps) and the fork trail achieved by welded on axle brackets was set in supermarket trolley position.

Should I say anything? Don't interfere says Sue but duty called and in my clean pub shirt and as politely as possible I walked over and had a chat with the parents. I explained what I thought was the problem, suggested that the bike would be much more stable with the forks the right way round and asked whether the bike had come from a bike shop. Inevitably the answer was no it had come from an on-line supplier and "I built it up myself". Fortunately they were lovely people and didn't take any offence at this old guy questioning their skills as engineers. Fifty years ago I'd have fixed it for them, because I would have been carrying a comprehensive set of tools in the car, but these days I've only got the basic wheel brace.

This is a surprisingly common problem - on a conventional bike it would just look wrong but a colleague once turned up with his new bargain internet bike with forks clearly pointing backwards. On Dr Bike duties at the Ride London Free Ride an experienced but rather shame faced mountain biker sidled up to me asking could he just borrow some Allen Keys? He'd been riding around for a while before he¹d realised that the suspension forks were the wrong way round after he'd slackened the bars off to get it into his car.

So lessons learned, always check that your own bike is properly assembled - wheels in firmly, quick releases safely closed etc. And at the risk of being considered a smart-ass, don't be afraid of politely making suggestions if you come across a badly assembled internet bike or even one being sold by a local supermarket. My friend Adrian Passmore, owner of Red Kite Cycles, would like to see legislation requiring all cycles to be put on the road after sale through a proper bike shop even if sourced from an internet supplier. They are vehicles after all with safety requirements and some suppliers will deliver the bike to a shop to be assembled and fitted to the rider. However, I suspect the the little pavement BMX in Henley might have been classified as a child's toy rather than a road going vehicle. That said, children's bikes in the cycling countries of northern Europe are anything but toys (and come complete with lights and mudguards), so perhaps we should follow their example.

Tips

The forks are reversed on both bikes shown in the photos on this page.

• On a bike with curved forks the mistake is obvious, as the curve is in the wrong direction (as per the photo).
• On bikes with straight forks, most notably those with suspension forks, the mistake is not so obvious. However, in both cases the front wheel axle and brakes should always be ahead of the forks, not behind them.
• If you encounter a bike in this state, it needs fixing as a matter of urgency. Don't work on the basis of "it's been OK up until now", because the bicycle's stability and safety will be affected.

Note that on recumbent bikes it can be normal for the forks to be reversed.