At the weekend, I was among the many cyclists who rode up the road that leads to the Roehampton gate of Richmond Park, London. About three-quarters of a mile long, this stretch is dead straight and so it is easy for cars to pass, provided there is nothing coming the other way. For about half that distance, there is a bike path marked on the pavement on one side of the road. In order to use it, therefore, a southbound cyclist (like me) would have to cross the lane of oncoming traffic and then, after about half a mile, re-cross the road to join the carriageway when the lane runs out. Along the way, the bike path is interrupted several times by driveways and side streets. No rational cyclist would ever choose to use it.

But that didn't prevent the 4x4 driver (aren't stereotypes comforting sometimes?), whose progress of speeding at 35mph was possibly impeded by having to drive at a law-abiding 25mph for about 20 seconds, shouting at me out of his side window to get in the bike lane and off the road. I suspect we have all been there.

It is such a common occurrence that it is trivial. Or would be - if we did not still face the threat of a revised Highway Code, due out this year, which is worded to allow the legal interpretation that cyclists might be guilty of "contributory negligence" if they fail to use available cycle facilities.

The old Highway Code text suggested simply that cyclists "use cycle routes when practicable". No problem there. The new code advises us to "use cycle routes when practicable and cycle facilities ... where they are provided".

Suppose, then, that Mr 4x4 Driver makes a hash of passing me and causes a collision. The new Highway Code could allow his lawyer to claim that I had failed to use the "cycle facility provided" and was therefore liable. You would think courts would not be so daft as to accept this argument, but never underestimate the asininity of the law: last year, cyclist Daniel Cadden had to appeal against a judgment of "inconsiderate cycling" in a case brought by police who had decided he should have been using an inconvenient bike path rather than the road. In January, with the backing of the cyclists' defence fund (www.cyclistsdefencefund.org.uk he won a retrial and was acquitted.

The Cyclists' Touring Club (www.ctc.org.uk) is ever alert to the issue and, with its encouragement, 11,000 cyclists have written to their MPs over the past year. There is also a Downing Street website petition (http://petitions.pm.gov.uk/roads4bikes) you can sign.

Meanwhile, when asked in parliament last week about the new Highway Code forcing cyclists off the road by its legal implications, minister Derek Twigg replied that: "The simple answer is that it will not."

Why do I not find this response wholly reassuring? Perhaps because of the considerable latitude for Sir Humphreyesque obfuscation opened up by what might be the "complex answer". Yes, minister?

Bike doc

Dear Matt,

Can you recommend a lightweight bike bag so I can carry my bicycle on long-distance coaches?

Lizzie Dale, via email

There are three options: an unpadded slip-cover type bag, a soft padded bag, and a hardshell bike case. The hard case is great if you also fly a lot. It's the only one that will fully protect your bike from baggage handling. Expect to pay £150-£200.

The padded bag is lighter and less cumbersome, and will save your bike from chips and dents due to rough handling. But a bag of this sort (£50-£100; DHB from the online retailer Wiggle, Evans' own brand, and Neil Pryde are all good) will still be too bulky if you need to pack it down and ride away from the coach station. In which case, go for a lightweight unpadded bag such as the Velox (£40), though I wouldn't trust it to an airline.

· Send your cycling-related queries to bike.doctor@theguardian.com