'Upgrading' to skinny tyres pointless for London commuting

You've discovered bigger tyres = lower rolling resistance, no surprise there, even the pro are going for wider rims to get lower rolling resistance.

I rode on 33.3c tyres, smooth and fast.

It's all still very CSB.

As usual Ed, you could make it very hard for people to believe that you have actually worked in a cycle shop. That is just wrong.

OP your conclusion is flawed because you changed your stem and bars at the same time. This could have made you ride faster, so your experiment proves nothing. Basic rule of science: change one variable at a time.

Ed bigger tyres do equal lower rolling resistance, but the power saving of the decreased rolling resistance is dwarfed by the power loss from increased drag and the increased weight of the tyres. They will also be slower going up hills and accelerating.

In other words your 33.3c tyres are more comfortable, but still slower.

You are correct good sir; but seriously, even a small child should be able to work this out, without being taught or told it. Tragic that it needs to be explained, to counter the nonsensical spoutings from our non-hearing comrade in arms.

edscoble...................taking Fail to whole new levels.