I just love riding this bike! Couple of changes I've made...I swapped on a set of cheapie stamped steel v-brakes and levers from my parts bin, just to see if I like v-brakes better than the stock cantis on this Trek -- and I like them a ton better. So I'll eventually swap these out for a nicer set of v-brakes and put these back in the parts bin for my next project.
I also traded wheels/tires with my Trek Verve, because I wanted to try the Continental SpeedRIDE tires I have on it, on
this Trek, and they're superb on this bike also. These are nominally 42-622 tires, and inflate to about 36mm at 40 psi (front) and about 38mm at 50 psi (rear). Both bikes share a 136mm drop spacing, but the Verve has an 8-speed cassette whereas the 750 has a 7-speed cassette. Cog spacing is close enough between them (4.8mm for 8-speed and 5.0mm for 7-speed) that they're effectively interchangeable. In fact, the index shifting from the Sram SRT-400 grip shifters is at least as good with the 8-speed set on the back as it is with the 7-speed. I just have it adjusted so that the second cog on the cassette is 1st gear on the shifter. I don't know any difference riding the bike and it works like a champ. I will likely pickup a set of these tires to mount on the 750's rims next time I find them on sale somewhere.
I also swapped on a Bell saddle from my parts bin that is narrower than I typically prefer, but it's more comfortable than the stock Velo saddle from Trek. In fact, the Bell saddle is comfortable enough that I'll leave it on for now.
I took a quick spin down some gravel paths through the park this evening. This bike is really fun.