Originally Posted by
mack_turtle
I am very aware of that. I also don't want a ball-smasher of a bike. there's a difference between no standover clearance and NEGATIVE standover clearance. I think the 55cm frame will have enough clearance to not smash my bits. I might go for the larger one in that case.
What are you trying to accomplish? If you want your bars level or at least close to level, or even higher than the saddle, most likely the larger frame would be the better choice. If you want the bars lower, then the smaller frame would be a good choice. The larger frame will have a slightly longer wheelbase, so it may feel more stable on fast downhills, while the smaller frame may feel more nimble to you.
I went with a larger frame when choosing my Long Haul Trucker, and am happy with the decision, and have been for the past 9 1/2 years of use. I could use their 54cm, and their 56cm frames. I chose the 56, it is comfortable and dead stable with a load at high speeds downhill, speeds up to 45 mph. It has a 90mm stem on it at the moment.