I've used a lot of different speedometers over the years. They all tell you the same info, so I go as cheaply as possible. I base my choice on wired vs wireless and ability to quickly remove it from the bike. I like the wireless ones that I can remove without tools, but the major downside is they chew through batteries like mad. If you store your bike for the winter with one of these, you have to remember to take both batteries out because the devices never turn off. I don't care for anything that has GPS because I can just use my phone for that.

As for going faster, I'll admit to being one of those who will automatically go faster if other people are around. But...I can't know them. If I know them, I'll want to chat and we won't go very fast. If I don't know them then game on. If I see someone up ahead, I just sort of focus on them until I pass them. I think it's the same thing that happens to me when driving. If there's a rider/driver ahead of me, they tend to take a lot of my concentration and I don't like that, so I pass them. And I keep the speed up for a long time after passing so that they don't get a chance to pass back, lol. And if they catch up, then I speed up again. If I'm utterly alone, this won't happen. In that case it's other stuff that will push me, like being late, being bored, needing the darn washroom, etc. Sometimes I'll race the bus if I'm on a bus route and I can see the bus coming up behind me way off in the distance and I don't want to be passed by it (some bus drivers are bad with cyclists).