I can see that if it's of little inconvenience, just dismount and walk the bike. However, I also appreciate that sometimes when you see a situation that is manufactured and is *their* fault, you do want to work a way round.
To that end: any chance you can cycle slowly up to the barrier with 10-20 cars behind you waiting to get in, leisurely dismount, check your tyres, unclip helmet, wipe your forehead, look aimlessly up into the sky, sigh heavily, think of England, and then move away from the barrier? Do that a couple of times and I'm sure they'll change the policy (but beware: they may change it to something worse!).
Really though, it's best to try to work it out -and if you don't get luck, it's up to you to decide whether the aggravation involved in making a point is worth it. Honestly, if it's just a couple of minutes, I guess I'd just accept it as part of the commute.