4 ms·

You don't believe those speeds are possible? When I was commuting to work before the pandemic, I would regularly keep up with city traffic at 40 km/h on a leve

You don't believe those speeds are possible? When I was commuting to work before the pandemic, I would regularly keep up with city traffic at 40 km/h on a level road for up to a few minutes at a time. (Now that they'll be lowering the speed limit from 25 to 20 mph, I'll be able to break the speed limit if I wish.) I've only once gotten up to 72 km/h on a downhill, keeping pace with traffic on a highway with a long downslope. I don't think I want to do it again, since the bike started to give a rather worrying 8 Hz shimmy, but I did it. I probably could have done 85 km/h if I'd kept it up continuously rather than sometimes coasting to keep my spacing. Both of these require me to give it pretty much all my power in my highest gear, but this is on a hybrid commuter bike with a full pannier and an 85 kg rider. I'm no star athlete. These speeds are well within normal bounds.

LargoLasskhyfv 6y ago
The shimmies! I've forgotten about them :-) Had them at 65. They were very unexpected when they happened the first time. And were gone at 67/68 again. I think they result from imbalances in the rims, due to the valves. And it varies with different frames-
- phyzome 6y ago
  It's actually part of how I know how fast I was going that one time. :-) I was on a 45mph speed limit road and I was keeping up with the cars, but I wasn't sure if they were following the limit. But I was later able to tap at the same frequency while looking at a watch and discovered it was about 8 Hz, and then took the outer circumference of my tire and calculated that it was about 45 mph as well assuming that an imbalance in the wheel or tire was the source. (My video camera had also caught some mile markers, but my speed varied in between, so those were only corroborative.)