foldable bike can handle fast speed

[DynV]

thanks to my awesome (for someone with small budget) garmin forerunner 305, I noticed yesterday that I went to 47 Km/h / 29 Mph downhill. the HRM mentioned I was at zone 5 ; my torso had a weird feeling like it was slightly burning or crushing a bit. even with my more than slight misaligned back wheel, I felt in total control ; I had no doubt that my front wheel would suddenly jerk aside or that the frame would start shaking like on a skateboard. well today I was shopping for a cheap better bike, thanks to the end of season, and stumbled on an awesome foldable bike, again with the budget thing.

having so recently experienced such high speed. I have mixed feelings on this: I just mentioned my fears of loosing control but I've also went on scooters on steep downhill at 70 Km/h / 43.5 mph with no fear although scooters have thick wheel frames, forks & tires.

I just saw a cool article, 650 versus 700c wheels - Are small wheels slow? 650 vs. 700c, which is convincing on the little-to-none loss of power using small wheeled bikes but I'm very worried about loss of power at high speeds.

 

[alienator]

thanks to my awesome (for someone with small budget) garmin forerunner 305, I noticed yesterday that I went to 47 Km/h / 29 Mph downhill. the HRM mentioned I was at zone 5 ; my torso had a weird feeling like it was slightly burning or crushing a bit. even with my more than slight misaligned back wheel, I felt in total control ; I had no doubt that my front wheel would suddenly jerk aside or that the frame would start shaking like on a skateboard. well today I was shopping for a cheap better bike, thanks to the end of season, and stumbled on an awesome foldable bike, again with the budget thing. having so recently experienced such high speed. I have mixed feelings on this: I just mentioned my fears of loosing control but I've also went on scooters on steep downhill at 70 Km/h / 43.5 mph with no fear although scooters have thick wheel frames, forks & tires. I just saw a cool article, 650 versus 700c wheels - Are small wheels slow? 650 vs. 700c, which is convincing on the little-to-none loss of power using small wheeled bikes but I'm very worried about loss of power at high speeds.

Wheels/tire combos only cost you power through aero drag, bearing drag, and rolling resistance. All things being equal, the 650 will be a bit more aero than a 700, but will have more rolling resistance. Bearing resistance won't change, all else being equal. Given the PIA of finding 650 road stuff and the limited selection available, I don't see any benefit to 650 whatsoever. Toe overlap is only an issue when making very tight turns at slow speed. It complicates nothing at normal or high riding speeds. If you were descending at high speed and turned your front wheel enough to have toe overlap be an issue, you'd crash from that large wheel deflection, not the overlap.

 

[oldbobcat]

In the '60s, Cinelli experimented with prototype road bikes with smaller wheels on the premises that roads were getting smoother so ramp angle was less of a factor, reduced surface area would generate less wind resistance, and the smaller mass would accelerate faster. I don't know if anything definitive came out of the testing.

The advantages of larger contact patches of wider road bike wheels and tires and 29" MTB wheels tend to support larger wheels. How large is optimum, I don't know.

49 kph going downhill on a road bike is commonplace. For those of us with canyons or mountain passes in our backyards, cracking 70 kph is not unusual.

 

[DynV]

the thread title mention foldable bike, the OP also mention it and the link show small wheels about the size of a foldable bike in its world records section.

I'm interested in something even smaller the n the mentioned 24". I'd put the bike in a rolling suitcase and it would never leave my line of sight. I live in a city which it's national sport is bike theft.

another time just to be sure: foldable bike.

 

[oldbobcat]

Well blow me down! I'd forgotten all about the bike John Howard set the world paced speed record on. There's definitely an opportunity for some experimentation here.

 

[DynV]

Originally Posted by DynV .

[...] I just saw a cool article, 650 versus 700c wheels - Are small wheels slow? 650 vs. 700c, which is convincing on the little-to-none loss of power using small wheeled bikes but I'm very worried about loss of power at high speeds.

I now understand how this was confusing, like so many times it happens to me, one word distract me and I use it instead of what I kept in mind. I meant control in my conclusion, my worry of loosing control, that is falling on the road or hitting a pole. /img/vbsmilies/smilies/frown.gif If someone want to get in on the issue, don't mind me. /img/vbsmilies/smilies/wink.gif

 

[alienator]

I now understand how this was confusing, like so many times it happens to me, one word distract me and I use it instead of what I kept in mind. I meant control in my conclusion, my worry of loosing control, that is falling on the road or hitting a pole. If someone want to get in on the issue, don't mind me.

The easy way to remove the worry is to not go faster than you are comfortable going. With that said, if you had a 650x23 wheel and tire as well as a 700x23 wheel and tire and if they both weighed the same, the 700x23 would have a bit more angular momentum (a measure of the wheel's resistance to being turned in this case, either by the rider or by a bump) because of its likely greater weight and it's greater radius. That's not to say a 650 wheel and tire combo would be unstable. Stability is dependent on more things than just tire and wheel size. It's also dependent on bike geometry and weight distribution as well as a complex relationship between the rider and bike with respect to how the bike/rider system responds to an impulse (a momentary force, if you will). What you need to be concerned with is that you exercise more control over what happens on your bike than your wheel size does. Don't ride outside of your limits/comfort zone.

 

[DynV]

And what would 20' wheel comfort zone be like? Would I feel... I don't know, say 20% less comfortable than on a 650c?

About the story: I was really disappointed of the bike, it's of bad quality ; I wouldn't go so far as awful because it seem sturdy, it's just very impractical. I wish I haven't bought it. The only use I'd have for it would be to carry it in a car if I had one as slow riding is the only thing I'd be interested in doing with it. Although even if weight wasn't an issue, with a car it isn't, I could prefer roller-blades to that slowpoke.

 

[alienator]

And what would 20' wheel comfort zone be like? Would I feel... I don't know, say 20% less comfortable than on a 650c? About the story: I was really disappointed of the bike, it's of bad quality ; I wouldn't go so far as awful because it seem sturdy, it's just very impractical. I wish I haven't bought it. The only use I'd have for it would be to carry it in a car if I had one as slow riding is the only thing I'd be interested in doing with it. Although even if weight wasn't an issue, with a car it isn't, I could prefer roller-blades to that slowpoke.

I don't know how you'd feel with a 20" wheel. The numbers don't address how you'll specifically feel. Can't you test ride a bike with 20" wheels somewhere?