The Wandle Trail is the best piece of cycling infrastructure in the Merton area. So you can rely on councils (Wandsworth I believe in this case) to spend money to make it that little bit worse. After all, we don't want to encourage cycling, do we?
On my ride home today I spotted this, at the Trewint Street end:
The wooden posts originally had steel scaffolding poles between them, forming a chicane which was fairly easy to negotiate. They've left the wooden posts in place and added two galvanized steel barriers, in keeping with the rural, countrified feel of the area, which are quite difficult to get through on an unladen bike. If you have panniers, or a utility bike, or a tandem, or one of those attachments for towing a child's bike, well that's your look-out and it serves you right for not going by car like normal people.
Why have they made this "improvement"? I have no idea. I've seen pizza delivery mopeds taking a shortcut along this piece of trail, but it really isn't that big a problem for anyone. There was a period where you would occasionally see a burned-out scooter on the trail, but this barrier won't stop scooter theft and the trail is still freely accessible from the Plough Lane end.
It's irritating to note how the rare occurrence of a small motorcycle using a cycle path attracts the zealous attention of the councils, and the result is more and more barriers getting put up, and real inconvenience to innocent cyclists. Yet motoring offences that pose a far greater danger to life and limb are completely ignored. Report a problem with speeding or dangerous overtakes to your council and you'll be met with amused indifference. After all, what do you expect them to do? They can't be expected to jeapordize traffic flow - if a few children get run down, well that's just collateral damage.