I'm looking for either a 48 tooth chainring (130 BCD) or a 3/32" 16t cog and I'd like to do a trade in nyc. The problem with being able to change my gear ratio is that every time I'd like to do it I have to spend $30 on a new cog. Wouldn't a trade system be smarter for a city like nyc especially considering that if you're using a 15t cog at a given time you're probably not using that 18t cog you once had installed... see what I'm saying? Anyways is anyone in nyc willing to trade or sell either of those for cheap? Do any nyc stores sell this stuff cheap? Thanks.