British science festival plan – Saturday 9th September, 2017.
Event title: The secret life of the bicycle: How science and engineering make the perfect machine.
Event organisers: Max Glaskin and Derek Covill
thanks everyone for a very enjoyable day! as promised, here is some of the information provided on the day, with some useful links also, keep in touch! Derek and Max
- Topic: introduction and history, did you know that…
…the first true ancestor of the bicycle (the Draisine) was invented as a means to transport people without using horses! This may have been the result of volcanic eruption of Mt. Tambora which erupted in Indonesia in 1815. It triggered temporary global climate change which stopped horse fodder from growing so horses starved.
- Topic: Steering and balancing – the human aspects, isn’t it interesting that…
…When we are riding quickly, steering can be used to gently manoeuvre the bicycle under our centre of gravity to keep us balanced like a fish swimming in the water. When we’re riding more slowly though, we can’t manoeuvre the bike quickly enough, so we move our knees to adjust our own centre of gravity in line with how we’re controlling the bicycle…and this is easier if we’re standing up than sitting down!
But we still make mistakes – probably because our “reach mechanism” affects the speed we tend to move our arms. Our brain directs our arms to complete a reaching movement in a specific time, not at a specific speed. So, the further you have to reach, the faster the arm movement. When you have to steer unexpectedly, this can create instability. Did you know that 60% of all cycling related A&E injuries have not involved anyone else in the crash!
- Topic: Self-stabilising dynamics of bicycles, it is truly astounding that…
…Bicycles are self stabilising (mostly), though nobody knew why until six years ago! It had been thought the gyroscopic forces of the wheels were the most significant factor – until David Jones, in the 1970s, nullified thse forces by adding counter-rotating wheels to his bike and it stayed self-stabilising.
Thanks to efforts in the last decade, it’s understood that bicycles are stable because of a combination of variables, like wheel base length, mass distribution, trail, etc. all working together to make it stable within certain speed ranges only. The mathematical equation required to solve the problem of bicycle stability is hugely complex and is still being refined..
- Topic: Resistance: what’s holding us back?
…The mechanical drive for a bicycle can be hugely efficient, sometimes 98% or even higher! But this is for a well lubricated system…with no grit!
The drag experienced when riding a bicycle is proportional to the velocity squared, so if you triple the speed then you’re multiplying the resistance by a factor of 9! At 9 mph, you’re using half your energy to push aside the air.
- Topic: Social science, perception and comfort
…Did you know that men are more likely to have their bicycles stolen? Or that women are more likely to have a near miss on the road, even though they tend to be given a wider birth by vehicles?
Some riders can detect a difference in tyre pressure of just 10 psi (from a reference of 100 psi), while others are unable to detect a difference of 30 psi? and other road users tend to underestimate the speed of electric bikes because the rider’s legs rotate more slowly – and that’s what’s used when estimating speed.
And according to the international health and safety standards limits for vibration and shock to the hands and whole body, these limits would be reached within only a few minutes of the Pari-Roubiaix race which typically lasts for over 90 minutes..ouch!