i agree. the high mileage on a brommie is definately more cleaning. weird things found in the derailleur system, lots of bits of glass micro-baubles. they jam up the system. week after week i find these little buggers.
chains don't last as long in the city. about 50% less i reckon. tyres are taking more of a hammering as well.
i used to read about people taking glass out of tyres and wondered what they meant. now i know, omg marathon plus can carry a lot of glass shards.
Possibly. I have been using Bontrager Race Lite Hardcases for the last few months, the rear one on my fixed, used mainly for commuting, has started to gain a collection of small cuts, which is not surprising as when I do my weekly check there's always a few small pieces of glass that need removing. As others have said where does it all come from? I don't ride in the gutter, I go round any broken glass I see and I only ride on the road.
Don't know if it still goes on but glass was being added to tarmac (old article here). I seem to remember glass manufacturers complaining about it as it then takes them something in the order of 10 times the amount of energy to create new glass than to recycle.