Eye witness account of the cycling accident.

FWIW, I have a lot of experience on gravel with rallying in WA, but no experience on tracks or road. I did a one-on-one driving course when younger and a hoon, in a pretty advanced sporty car without ABS. The instructor demonstrated locked and unlocked braking on dry bitumen and on gravel. He was able to convince a very sceptical me that locking it up is best, up to a point.

On dry road in normal circumstances, an untrained driver (i.e. a driver who isn’t a competitor) in a modern car at legal speeds will stop in the shortest distance by simply applying the brakes as hard as they can. The reason is simply reaction time. An untrained driver will not apply the brakes correctly and will waste time manipulating them. He would have been better off getting rid of that kinetic energy by immediately applying very hard braking.

For drivers with motivation to practice, Ellingly above is right, the best way is to brake hard to get the weight on the front wheels and to allow the front-rear bias-valve to take up its adjustment, and then to literally stand on the brake pedal. You would be absolutely amazed at how short you can stop without locking. The G force was so great that I was out of my seat and held back by the seatbelts and I was, as I say, literally standing on the brake pedal.

For gravel, it’s a no-brainer. Just stand on the pedal. The locked tyre digs a ditch and the gravel builds up in front of the wheels to give a sort of up-hill effect and slowing the vehicle very quickly.

Nowadays with ABS, it’s all moot. The hardest thing I find is overcoming the training of my youth and not trying to manipulate the pedal, just stand on it as hard as possible.

Ahem, I did mention “On a dry road”.

And here’s a physics site that looks at stopping distances: http://hyperphysics.phy-astr.gsu.edu/hbase/crstp.html
Interestingly, it indicates that on a dry surface the difference between locked and hard stopping was not apparent. Locking is not so good for the tyres though!

When I was younger and sillier, I discussed this with a friend in the context of locked wheels in the dirt stops quicker than hard braking. Even then we knew that on tar hard braking at near lock up is best. We decided to put it to the test in his mum’s Laser. The dirt was much harsher than we expected on a locked tyre and we flat spotted it. Scientific results were inconclusive and his mum was p1ssed off!

A car takes much longer to stop when the wheels are locked. Reason why is locked wheels slow down the car less quickly because the braking surface is the tar and a film of molten rubber where the tire contacts it, rather than carefully-engineered brake pads and brake discs. This is far more apparent in the wet, where once lock-up occurs, the water is simply allowing the locked wheel to glide over the road surface.
I may be a strong cycling advocate, but I had a hoon upbringing and used to hill climb cars, dirt bike ride and ride sports motorcycles.

sounds like a job for mythbusters

or does anyone want to organise a trial?

A locked up car does NOT slow quickest!!! This is why ABS stops a car more quickly by allowing the wheels to maintain traction near the brink of skidding.

Utter *nonsense* based on sales-pitch hype. (I have a large bridge for sale if you’re interested…..)

On a dry road, locked wheels result in the shortest braking distance. However – locked wheels also means minimal/no steering control, which is the trade off.

A tragic accident during a sporting event is what needs to be focussed on here. The question of leaving the road open or closing it during such an event needs to be resolved. To broaden the discussion to cyclists’ perceived bad habits in urban Canberra is bizarre.

OYM.

I appreciate your argument. Certainly there are European countries where pushies are king. Certainly there is a less than glorious future for oil.

But I am less than convinced that pushbike riding will save the planet. As I have said, this will be a very hard sell to the vast majority. I contend that any wholesale shift to pushbike riding by a proportion of the populace will result in a (disproportionately) high increase in accident/injury/fatality rate for riders. Good grief, we whinge about P plate drivers, how do we account for any misadventure by inexperienced pushy riders?

I am unsure that we are ready for a total change of mindset to encompass the inclusion of a pushbike riding culture. It will take years for this to take hold, because there is no immediate, overwhelming reason to believe that pushbike riding is any answer to the problems we are currently facing as the ratepayers of the ACT.

Well, Cranky, you don’t need that much of a shift in things to change that. My workplace has a roughly 25% level of participation (120 staff). I’ve been to places in Europe (cold places too) where cycling is embraced.
Here’s another very strong argument. Australias oil supply is in decline. We are now using 800k barrels a day and only producing 600k. America was a net oil exporter and now only produces 5mil barrels a day and consumes 21mbd. That 16mil difference has to be made up. (Reference BP Oil Report- see previous link). Consumption increasing and production declining is not a good situation.
There are alternatives, but none compete with oil for one reason or another. We don’t need to get that many people on to bikes to make a difference.
The incentive of promoting cycling really isn’t costly, Cranky, the alternative is.
In terms of danger, cars are the shocker. As I’ve said in previous posts, the costs of motor vehicle road trauma exceed all the fees/taxes and rego that you pay on your motor vehicle.

This has to be a ‘Chicken and Egg’ arguement.

Or a ‘Build it and They Will Come’

When pushbikes reach plague proportions, perhaps we can open the coffers to pander for this breed of citizen. However, should we be funding a very small proportion of the population to fulfill their idealistic goals?

Push bike riding will only ever be attractive to the few. Providing Rolls Royce facilities/road conditions is unlikely to attract a quantum leap in useage. For heavens sake, it is a bloody dangerous pastime for a start! And that’s just on health grounds, without mixing it with motorists.

So should we be providing the (costly) incentive to attract people to push bike riding, or, as in every other aspect of Government, reacting to a need?

Conservation Council is calling for no registration of bikes as it would mean less people would take-up cycling. Also crashes from bikes are not that serious:

consact.org.au/images/newsletter/april_2007.pdf

Commuting to the new suburb sounds logical for a cycling lane. In fact all new roads should include a cycling lane. It costs very little extra and is of huge benefit to the community – same as footpaths. But retrofitting to the cotter for recreational cycling doesn’t make sense to me (and I am a regular recreational rider of the Cotter area).

It’s strongly in the interest of the Govt to aim for maximum takeup of commuter cycling for all the obvious reasons – less smog, less road wear and tear, less traffic & parking hassles, less CO2 emissions, healthier population etc. etc.

For riding to Stromlo Park and commuting to the new suburb, not relevant to racing. Accurate as any other news report!

The long course on Sunday also went out through the Cotter, through Tharwa, to Honeysuckle Creek. Hard to close all of it.

I applaud the ACT Cycling group for their call and wish them well in their efforts in raising the necessary funds to widen the road and add a cycling path.

That’s going to be some real money.

The ACT Cycling group has now called for the Cotter Road to be widened and a bike lane placed along it to cater for the racing cycling community. Saw it on WIn just now.

mcjimminy – it’s a common mistake, but locking up your wheels bleeds off less kinetic energy than disappating it through the brakes (which is what happens when your wheels aren’t locked).

If you got the most efficient transfer of kinetic energy to other energy (which is what slows you down) then doing a burnout would be the fastest way to take off. Which it isn’t.

Maximum grip by a tyre is given by about 5% slip, the problem is, 5% slip when braking tends to start it locking up, which unless you do proper threshold braking, will persist with locked brakes.

ABS lets you steer around obstacles, yes, it also doesn’t defeat the laws of physics. On a dry road, it’s about as efficient as someone well trained in how to emergency brake. On a gravel road, it sometimes isn’t the most efficient, but we’re talking 1-2m extra, at 80km/h, which is offset by the extra ability to swerve (significantly harder without ABS on gravel than most people realise!).

The secret to stopping hard is to get you extra traction on the front, using weight transfer. You start off braking hard, and you just keep on laying on the pedal. You’d be surprised just how much extra braking effort you can put in. If you lock up the wheels, not only do you have less traction cause the tyres are sliding, but you also have less force pressing down, providing you less traction.

I don’t have any online references for this, but it’s in numerous advanced driving manuals… which I’ll cite when I’ve moved house.

Got the ABS comment in the old thread too. My response is:

I’m not sure that you’re right. I thought ABS was designed primarily to allow the driver to steer around the obstacle to avoid a collision, as locked up wheels can’t steer–a matter of control (and even tyre wear). Absolute stopping distance is a different issue. I may well be wrong, and it would definitely depend on conditions (wet, dry, gravel etc). Google doesn’t turn up much regarding absolute stopping distance on a dry road. I’m interested to know though, and happy to learn more from a reference to a study or something–not that I can turn the ABS off, or would want to. I do remember reading somewhere also that often people don’t press hard enough on the brakes in an emergency situation, which is why manufacturers are starting to put in sensors to detect emergency braking and automatically engage the brakes as hard as possible (though in conjunction with ABS). Anyway, that’ll learn me, even though that bit was with the speculation/opinion.

Regarding alternate routes. It was my impression that the route did include the Uriarra road as well–providing a loop back to the starting point. If this course was closed, then the only way to access the Cotter and Tidbinbilla would be south via Point Hut Crossing (which you may well only discover after you get near Duffy, making for more than a 48km backtrack and detour if you were off to the Cotter), and you’d be pretty much screwed if you’d planned on heading anywhere up the Brindabella road like to Mt Franklin, Mt Coree, Blundell’s Flat, the Brindabella Valley etc.

For what its worth, a reasonable detour to the Cotter would be via Uriarra Crossing. Not ideal, but much quicker than the Tuggeranong route mentioned by the author.

Actually, from what other people said, it is my understanding that the racing went along Brindabella Road, which would mean that there would be no access from Uriarra Crossing to Cotter. The only sealed road access to Cotter would be from the South, via Point Hut Crossing (since there is no bridge at Tharwa…)

I just wanted to clarify that I was pointing out a factual error, and not trying to lay any blame for skidding to the driver.

If you drive on the parkway in the morning on a regular basis, it’s clear that when in an emergency braking situation most people lock up thier tires.

“and heavy brake foot (a locked up car slows quickest, “

A locked up car does NOT slow quickest!!! This is why ABS stops a car more quickly by allowing the wheels to maintain traction near the brink of skidding.

Thanks for that, mcjimminy. Nice to read an account that isn’t soured by emotive language and finger-pointing.

For what its worth, a reasonable detour to the Cotter would be via Uriarra Crossing. Not ideal, but much quicker than the Tuggeranong route mentioned by the author.