With the sad news of the woman who was killed by a cyclist recently, and talk on brakes, I started wondering if anyone's seen any tests comparing stopping distances? MTB vs road bike with rims vs discs vs fixie etc.
Never seen one myself. Would be interesting to see bikes braking at the same time from the same speed... just a thought.
http://singletrackworld.com/forum/topic/charged-with-manslaughter-riding-a-fixie
It's all in there somewhere...
ah...I better have a coffee first
Don't forget some biscuits...
Found this one in there:
http://news.met.police.uk/videos/comparitive-stopping-distance-test-between-cycles-30256
Not a very scientific test but interesting to see the comparison.
Could be done a lot better: multiple attempts, riders of similar weights riding side by side, in the rain etc.
Something for Singletrack maybe.
Can't be bothered trawling the whole thread ....
Surely if a brake can lock the wheel then the tyre/road grip is the prime influencer of stopping distance rather than brake type.
That being said, there is no doubt that my cable pulled cantilever cx brakes are miles worse than road brake calipers which in turn are worse than disc brakes road rims.
I'd say my cx brakes would have at least twice the stopping distance of road brakes. In fact in the wet coming down the haylie brae I can't even get the bike to a standstill at the lights at the bottom without putting a foot down ... they are that bad.
Coming soon from Shimano: ABS.
Cougar...4 real?
I'd say my cx brakes would have at least twice the stopping distance of road brakes. In fact in the wet coming down the haylie brae I can't even get the bike to a standstill at the lights at the bottom without putting a foot down ... they are that bad.
Sooo...should that bike be allowed on the public highway?!
Cougar - Moderator
Coming soon from Shimano: ABS.
I totally bet it's on the drawing board somewhere...
[img] 
[/img][url= https://www.rosebikes.com/article/shimano-sm-pm70-power-modulator/aid:287831 ]This[/url] already exists
My folks bought matching hybrids with them attached
"We don't trust you not to brake too much: this is here to limit the amount of braking we'll allow you"
Thanks shimano
Edit: yes, it's not ABS. I know.
I'd say my cx brakes would have at least twice the stopping distance of road brakes. In fact in the wet coming down the haylie brae I can't even get the bike to a standstill at the lights at the bottom without putting a foot down ... they are that bad.
Are they set up to maximise mechanical advantage and with good blocks?
http://www.sheldonbrown.com/cantilever-geometry.html
It's strange ... They kill the high speed coming down the hill fine... I can get down to sub 10mph fairly well but it's like they fade at the lower speed in the wet. It's like a half-life curve ... Never quite reaching zero. In the dry they are ok.
The bike is getting relegated to the turbo soon but I'll look at the Sheldon site and compare.
[quote=ooOOoo > http://news.met.police.uk/videos/comparitive-stopping-distance-test-between-cycles-30256
Not a very scientific test but interesting to see the comparison.
Scientists are offended by the use of that word in relation to that test. It's not even useful as a means of comparison.
I mentioned it on that thread several times, but the ultimate limit on braking with a bicycle (with a front brake) is the geometry - with a decent brake and a reasonably grippy surface you can brake hard enough to lift the back wheel up and tip yourself over the bars. With a typical riding position the back wheel will lift when the braking deceleration is ~0.5g (that is the generally accepted value, though it varies a bit depending on the position adopted).
For a proper test, reaction time should be included - rider should start braking at the sound of a horn or something. Then the position at that time would need to be recorded as well. Would the reaction time for an experienced fixie rider differ from that with brakes?
Would be interesting to see bikes braking at the same time from the same speed... just a thought.
Surely it depends if its an angry Londener riding the bike?
I remember these from back in the day. I found the photo on Google but the mtbr article it came from doesn't seem to explain how they (were supposed to) work...
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I would be interested to see the stopping distance compared between a bike at 18mph and a car at 33mph.
Stopping distance from 18mph (assuming the 0.5g alluded to above), with 1.5 seconds thinking time, is 19m.
Equivalent distance for a car at 30mph is 37m.
What's interesting for me in the case is that the prosecution used the fact he wasn't wearing a helmet as a justification for him being "reckless".
What's interesting for me in the case is that the prosecution used the fact he wasn't wearing a helmet as a justification for him being "reckless".
They can use whatever they like and will try to do so. It's the job of the defence legal team to rebuff such nonsense...
More on the BBC site:
http://www.bbc.co.uk/news/uk-41036581
"People do it because it's this personal sensation of control with the bike. You never get that quick in London, it's more about how you cycle. I think most couriers who spend hours riding every day have the credentials."He does admit you "can probably slow down quicker with a front brake".
Scientists are offended by the use of that word in relation to that test. It's not even useful as a means of comparison.
Ha, good point, and I guess that is why I'm surprised there's not been more science applied to this area. What with all the 'science' that is applied to our expensive bikes.
You should only travel as fast as you can brake. True for bikes, cars or any vehicle. Didn't realise so many couriers were on fixies, and if they are justifying it cos of their 'skillz' then what utter tools they are. Surely if you're doing that job you want the best brakes available?
Maybe a maximum stopping distance for bicycles is a good idea.
the ultimate limit on braking with a bicycle (with a front brake) is the geometry - with a decent brake...
So how do we define decent?
[quote=ooOOoo ]You should only travel as fast as you can brake. True for bikes, cars or any vehicle.
That's a meaningless statement - I'm not sure if you meant "you should always be able to stop in the distance you can see". Though in any case that doesn't help if a pedestrian steps out into that space - unless you're suggesting men with red flags. Arguably you should take more care when there are pedestrians on the pavement looking like they're going to step out, but I'm still not sure if the pedestrian was visible before they appeared in the road in this case - there was mention of a lorry loading where the collision happened.
It's also worth pointing out that there would be no outrage at a car doing 30mph there, and the HC stopping distance from 30mph is 9m thinking, 14m stopping. epicsteve did some really useful testing on that other thread and managed to stop from 18mph in 11m using just the rear brake - a fixie probably wouldn't stop that quick, but not far off with a skilled rider (I'm ignoring the police video and evidence as useless). http://singletrackworld.com/forum/topic/charged-with-manslaughter-riding-a-fixie/page/12#post-8662522
the ultimate limit on braking with a bicycle (with a front brake) is the geometry - with a decent brake...
So how do we define decent?
By circular argument, one strong enough to pitch you over the bars 😉 Though that's not really the point - that's the best you can possibly do on a bike, real world stopping distances are likely to be longer whether or not that's due to a less decent brake.
the ultimate limit on braking with a bicycle (with a front brake) is the geometry - with a decent brake...
Are you sure about that?
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I remember these from back in the day. I found the photo on Google but the mtbr article it came from doesn't seem to explain how they (were supposed to) work...
See that wheel thing? It pushes the brake away from the rim for a split second every rotation. It's not ABS, more very quick pulsed braking. Wonder why they didn't catch on 🙂
[quote=matt_outandabout ]Are you sure about that?
Yes - it's the ultimate limit, doesn't mean there aren't things which will decrease it.
Though you should also be careful about arguing with quotes which other people have already snipped - the next bit after the snip was "and a reasonably grippy surface" 😉
That weird brake thing above wouldn't be a benefit if it reduces braking every revolution. The effort only needs reducing if the wheel locks, hence no revolution and the gadget not working.