I have two Specialized Langster (one brand new 2013 model (54 cm) and the other a couple of years old unique London model (52 cm)) - both are single speed. Got sick of getting punctures on my daily commute so on Monday I got Durano Plus 700x25c tyres - the bike shop owner said go for 25c as the 23c is good but for daily commuting he would recommend 25c - he did acknowledge you will go slightly slower but not that you will really realise.
Well, he was wrong and I have realised! Anyway, the problem is the London model seems to be a lot slower then the the one - both are slower now but the London one lot more.
I am able to really pedal the heck out of the London one but it just does not seem to go too far I know I can pedal more but there is no need as it just does not cope to go further (hope I am making sense as it is hard to explain!). Could it be the chain is just not good enough on the London model then the other bike? Or something else - there is nothing much else I can think of as it just has one chain and no gears and stuff - except for the new tyres??
One point - the chain is painted (as it is a unique London model) so could it be that? I only bought the London model two weeks ago and am only now riding it around now for my daily commute.