I avoid the Shimano bikes at all cost due to the low gearings (and the usually terribly spongy brakes, which one frequently don't realize until hard braking is required).


I almost always ride the S/A bikes unless there isn't one available, and if I ended up with a Shimano or a NuVinci with no overdrive, I usually ride it to a station on the way that has plenty of bikes and swap it for a S/A one (not a big deal ever since they removed the 2min wait time, but I don't fully gear up (tie up bag, etc). One bad thing with the S/A hubs is once in a blue moon, I will get one that slips off the top gear. It would throw me off balance if I don't have my hands on the grips, or worse, if I was standing up, my foot would drop and in both cases, have almost crashed a few times. I just have to remember to maintain pressure on as much of downward cycle instead of just on the 2-5 o'clock range.


As for the NuVinci hub, I still pick that over the Shimano, but I can usually tell if it has an overdrive gear after riding 50 ft, and if it is ridiculously low, I would turn back and switch to another one, or just switch to a S/A on the next station. A few times, even with a NuVinci that felt like it has overdrive, I feel like there is some kind of drag, like I am riding in a dirt path. Other times, when I got a NuVinci w/overdrive, I ride and feel like I am flying, only to check my app to find out I was doing not much different than when on the S/A bikes. Maybe the higher gearing is offset by the increased drag. I have done the S/A on HR bike path with tailwinds (or stayed on with some wed morning pack coming back from GWB) and have always been limited by cadence, always wanted to find out how it would be w/a NuVinci w/overdrive, but never had the opportunity.


I frequently press the service button when I get a NuVinci bike with too low a gear, but I don't know if they know what the issue is since there is no section to fill out on what exactly the problem is.