Hi, newbie here. I recently upgraded from a Raleigh Hybrid to a Trek FX 7.1. I bought it used, the previous owner upgraded it to be more like a road bike and I added a carbon fiber post. Anyhow, this bike really moves out, but it is set up for 21 speed and I find myself in 3-7 way too often, and maxing out on downhills. Looks like changing out to a higher gear set up is more than what the bike is worth. But I am probably a year away from getting a "real" road bike. The question is; Could I change out the 48 tooth large chainring for a 50 or 52 and increase my top speed without screwing up the current deraileurs? Seems like a possible solution if it would work for about $50, but short of adjusting the gears, I have limited experience in this field.