Danny MacAskill

[threaded]

That is phenomenal. Please tell me you need a specially sprung bike in order to do anything close to this. The heights he managed to jump were amazing. I'm happy just getting up and down kerbs without terminally wrecking my (unsprung) bike.

For starters, you are best doing it on a bike that doesn't have a seat (or seat tube).

They tend to have a lot of flex in the frame (as compared to a racing bike), but no other suspension. You'll no doubt notice what looks like a dérailleur on the back wheel, actually they're single speed and it's a chain tensioner to allow for flexing in the frame.

On the big jumps, you wreck the wheels on each outing, and they need tuning, truing or rebuilding. Which is all part of the fun. I think on the video, at one point you can see, he's trying to bash the wheel back into shape.

For some of the tricks you need a special braking system to allow the frame to go round and round the handlebars, and in others you need a very powerful braking system. Which are mutually exclusive, or as is the way with bicycles, you need to pay. So you also need more than one bike.

To brake the rear wheel sometimes you can get away with a 'flip flop' hub so you can have a fixed cog on one side and a free-wheel on the other (and then use a rim brake). But such wheels are by their very nature weaker, so again extra wheels for each class of trick or another bike.

Chains are very strong, but still get snapped, so spare chains on an outing are necessary or it can be a short day. Carrying a chain tool, and knowing how to use it, is a must.

Meditation techniques, such as control over breathing and slowing your heart rate...

[threaded]

Check out the bit at 1:26 where he rides up the tree! Can i use the word 'gnarly' (haven't a clue what it means but am sure it's something to do with people riding bikes up trees)?

Gnarly means a path that cannot be taken by those lacking fu.

HTH

[scooterscot]

I'm wondering if this is the guy I see in the unicycle around town all the time, usually I'm in the gym doing these floor exercises and beneath the frosted glass there's this guy flying off steps on one wheel...

[scooterscot]

So threaded when you going to get a wheel with spokes that can stretch as well as compress? Could be a lucrative plan B.

[threaded]

So threaded when you going to get a wheel with spokes that can stretch as well as compress? Could be a lucrative plan B.

Stretchy spokes, oh dear... You can get titanium spokes, which are quite stretchy in comparison to the high chromium steel which is the best choice. You can get carbon fibre spokes which don't stretch at all, but when they fail, due to the failure mode, it's generally quite nasty for the rider. Most bikes come with machine build wheels using high carbon steel spokes, which is quite the worst possible choice of material, but it's very cheap.

Actually...because I break so many spokes, I took to looking into what goes off in bikes, in mechanical (physics) terms, even one time fitting some strain gauges to various parts, even the spokes.

The results were counter-intuitive, such things as when you load a wheel the stressed spokes are those at right angles, not those on the other side of the hub... On a dished wheel, i.e. allowing a gap for the disk for the brake, the 'un-dished' side is the one with the spokes doing most work...

Oh, and when you're going at speed all bets are off... you actually steer in the opposite direction you want to go, that causes the lean into the bend and then you precess around because of the curvature of the front wheel tire along with your wheel taking up this taco shape. Which...(are you still there) if you're running at low tire pressures isn't happening, so you end up carrying on in a straight line... but, if you have a heavy (i.e. knobbly) tread you get centrifugal force recreating the tire curvature, so you win it back again. Which is my theory for why there's such a massive difference in cornering speeds for various riders, i.e. there's a speed range on a low pressure tire where you can't corner, above and below is ok, but there's a patch in the middle, at bicycle speeds, where you will just crash.

Now, to solve that, what you could do is put weights on the spokes that move out as the wheel speed increases, i.e. increasing the centrifugal force. So a little weight, like a piston, around the spokes, with a light spring to the hub. At low speeds the weights are up with the hub, at high speeds they move out...

Yeah, I thought, patent application time. But like most things with bicycles, not only is it an old idea, you can even buy it off the shelf if you know where to look.


I could talk about the back wheel next if you want...

[threaded]

I'm wondering if this is the guy I see in the unicycle around town all the time, usually I'm in the gym doing these floor exercises and beneath the frosted glass there's this guy flying off steps on one wheel...

Not uncommon in Copenhagen. Saw 7 in one group all riding together one morning. Made me laugh as they distracted motorists as they milled about like a swarm of flies as they were waiting at a red light.

Then there's a total babe friend of mine who rides a 29er unicycle, in skin tight lycra. Because such a thing goes so fast it has a brake with the lever under the seat. Looks interesting, to say the least, when she has to use it to stop.

[scooterscot]

What I'm thinking is a hub that can change it's position central to the wheel upon a hard landing. Make the whole wheel a shock absorber when it is not at speed. Na forget it it would not work, otherwise how could you jump, it would need to be an active shock, too much gear too much weight.

I used to fly down the forestry commission tracks (letting down the tyres became common practice after a blowout and I landed several meters in front of the bike) many moons ago - I went through a couple of wheels n all.


yep - once made a digital hearing aid that could cancel out GSM RF & EMI about 15 years ago, gulp, and sat on it until someone could be bothered patenting it - oh dear.

[minestrone]

I'm wondering if this is the guy I see in the unicycle around town all the time, usually I'm in the gym doing these floor exercises and beneath the frosted glass there's this guy flying off steps on one wheel...

Across from the conference centre?

[scooterscot]

Across from the conference centre?

I've been rumbled. That's the one...

[minestrone]

I've been rumbled. That's the one...

Ha Ha.

Used to walk past it every day and think if that the frosted glass was not there it would be some great perving opportunities at the lassies bouncing breests.