Author Topic: Balance bike and scooter simultaneously?  (Read 3337 times)

Kim

  • An appetite for the epic, but no real stamina
Re: Balance bike and scooter simultaneously?
« Reply #25 on: April 13, 2017, 03:52:14 pm »
Some stuff about bikes for children here (with things that I don't understand about gear ratios).
http://deceasedcanine.blogspot.co.uk/2016/05/how-to-choose-kids-bikeor-why-its-not.html

Nice spreadsheet, but it falls short of calculating the actual gain ratios.  Would be interesting to plug those numbers into Sheldon's calculator...

I'm not sure I agree with the original premise though.  A child on a Beinn necessarily has much shorter cranks than an adult on a Dahon or a Helios, so for a given gain ratio, I'd expect them to pedal at a higher cadence to achieve the same speed.  A child is smaller than an adult (ie. their small legs can't make the pedals move in as big a circle), so to achieve the same speed they're either going to have to pedal at a higher cadence, or push a higher gear, and as anyone who's ever ridden a bike knows, high gears don't give you speed for free.

Expecting children to push teethgrinder gears in order to keep up with adults on bikes is about as reasonable as expecting them to run in order to keep up with adults walking.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Balance bike and scooter simultaneously?
« Reply #26 on: April 13, 2017, 07:03:06 pm »
Look at the weights. The lightest bike in that table is the Islabike Cnocc 14 small, at 5.6kg. Really light! But that's for a 3 y.o. who weighs on average 15kg according to this table. http://www.onaverage.co.uk/body-averages/average-child-weight Islabike also have the heaviest, the Luath 24 at 9.05kg, for an 8 y.o. with an average weight of 26kg. So in both cases the bike is about a third of the rider's body weight. And these are the top end of kids bikes; imagine a 75kg adult considering a 25kg bike to be lightweight. It's obvious kids are going to have to put in a lot more effort up even modest gradients (and probably have more trouble controlling the bikes on downhills).
The earth is vast and beautiful and contains many miraculous places. (Chekhov)

Kim

  • An appetite for the epic, but no real stamina
Re: Balance bike and scooter simultaneously?
« Reply #27 on: April 13, 2017, 07:59:27 pm »
Yes, that's the other thing.  To a child, all bikes are loaded tourers.

I suppose aerodynamics can mostly be handwaved, on account of low speed, relatively small frontal area, and making good use of the boundary later.

I wonder if anyone's fitted an child's bike with a power meter and obtained some real-world figures?  If they have, they're probably on YACF...
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Balance bike and scooter simultaneously?
« Reply #28 on: April 13, 2017, 08:19:29 pm »
Going back to the spreadsheet for a mo, not only does it not mention gain ratios it doesn't calculate straightforward gear inches (or development, whichever you prefer). With an assortment of wheel sizes, my brain asks for a pencil and paper to make sense of the combinations.
The earth is vast and beautiful and contains many miraculous places. (Chekhov)