Riddle: You have a bike....

[RobinJI]

On 24/04/2017 at 1:19 AM, Hopping_Topsy said:

 

Well, this would depend on the gearing wouldn't it?

Let's say you have a fixed point in the room, let's say where the BB is, and you'd have a sufficiently light gearing you could pull back on the crank and the crank would move away backwards from the fixed point faster than the bike would move forwards, leaving the bike traveling forwards with the crank actually traveling 'backwards' until it gets to the point Ali brought up?

 

That is a good point too, you can tug backwards on the string whilst standing on the front of the bike too..

I'd agree with this. The gearing is very relevant. As hopping_topsy says, if the pedals movement rearwards is greater than the distance the cranks rotation attempts to move the bikes tyre, then there will be an initial movement forwards. That is up to the point where the rotation causes the pedals movement to become too vertical, so not very far. My instinct would say that the gearing needed to do this would be very, very low though. 

If the tyre doesn't slip, the bike's held upright and enough force is applied, then sooner or later the bike's going to try and wheelie (if the force is applied from a distance behind) because of the moment arm between the tyres contact patch and the height of the cranks. 

[manuel]

Wouldn't a wheelie depend on whether the bike was a high bb pogo trials bike or a normal one?

[Greetings]

2 hours ago, manuel said:

Wouldn't a wheelie depend on whether the bike was a high bb pogo trials bike or a normal one?

Don't think so. You're always going to be pulling higher than the point at which the tyres touch the ground.

 

Going to leave these here...

 

[Tony Harrison]

On 25/04/2017 at 3:23 PM, Paperclip said:

Love a good head scratch like this, actually did similar things at college.  

I used to love a good butt scratch, turned out it was worms, and scratching just became part of my life, it blended in to the extent that tearing holes in underwear ended up being a normal daily occurance. Sometime later I decided to co-habit for a while and I thought it unfair that she should have to share a bed with me and the worms. So I went to see a doctor (people had been telling me for ages, "Just see a f**king doctor!") and he asked "How long has this been going on for?" "About two years" I replied. "WTF" his face seemed to say. A simple prescription of three tablets to be taken at 24 hour intervals got rid of the worms and several days later it hit me: I'm not scratching anymore! There really was life after worms.

[Greetings]

 

3 minutes ago, Tony Harrison said:

I used to love a good butt scratch, turned out it was worms, and scratching just became part of my life, it blended in to the extent that tearing holes in underwear ended up being a normal daily occurance. Sometime later I decided to co-habit for a while and I thought it unfair that she should have to share a bed with me and the worms. So I went to see a doctor (people had been telling me for ages, "Just see a f**king doctor!") and he asked "How long has this been going on for?" "About two years" I replied. "WTF" his face seemed to say. A simple prescription of three tablets to be taken at 24 hour intervals got rid of the worms and several days later it hit me: I'm not scratching anymore! There really was life after worms.

24 hours? Not 7 days? I had worms probably for a few months but there was no butt or head scratching involved. Lost 20 pounds, looked like death but my friends were too kind to hint at that  

Then my wrist broke during a tap  Seriously, f**k worms! 

How did we get from a bike riddle to parasites again?

[JT!]

Answer in white:

Depends on the gearing, crank length and wheel size etc... might even depend on the grip of the type to the floor too. If the gearing (and other variables) are low enough, the bike will move forwards, if the gearing to too high, it'll move backwards.