So no front wheel lock then?

has no one noticed she braked literally just after a small drop down? He hit that at the moment she braked so he pretty much landed on her back wheel.

How the **** is he meant to brake in that situation ?

No doubt in mind she really hauled on the anchors & I mean like grabbed a fistful of both! Having said that he should have given a her a shout that he wanted to pass & not tried it on a bend.

And what the **** was with all wounded soldier sh1t she was trying to pull. Ok I know shock but come on!

Well I would say it’s her fault. Yes he was quite close but nobody expects someone to stop suddenly like that. Also I think he’s too nice, I probably would’ve just checked she/the bike wasn’t seriously hurt then **** off and enjoyed the rest of my day 😆

her throwing the bike at him in that situation could be considered assault with a weapon get her done!!

also the point about it being a “team building day” given all the protection kit etc would mean she had signed a disclaimer stating she would be undertaking a “extreme” sport so she couldnt sue him!!

I’d say they were both partly to blame. If i was going down a busy trail and knew that there was someone behind me, if I slammed on my brakes without making any signal or moving over I would expect to be whacked. Stopping slap bang in the centre of the trail is just stupid.
But, it didn’t look like he tried that hard to stop in time; I am not sure he was paying full attention.

She completely over reacted and didn’t really appear injured until her mates showed up. She was completely unreasonable, especially considering how apologetic he was.

TJ – I’m not so sure you could stop in 5m on a gravel trail travelling at 20mph.
20mph is 9.1m/s which would mean you’d have to stop in 1.1s using S=1/2(U+V)T where S=5m, U=9.1m/s & V=0. Working out your acceleration once you have the time, you’d have to decelerate at 8.72m/s^2 which is nearly 1g.
Looking online, various sources reckon the best sports cars achieve 1 to 1.5g while braking (the Veyron is apparently 1.3g) and presumably that’s on a tarmac surface.

(sorry, I’m a bit bored)……… 🙂

It’s entirely his fault because he should be viewing the rider in front as a moving obstacle and be prepared to slow or stop (as required) depending on what it does. You don’t try to pass people, on any grade of trail, unless they let you go – which is really the only way you know for certain that they know that you are there and what you are about to do. If somebody is crawling along the trail it’s just tough sh*t: your flow is gone and you just have to try again next time.

That said, the rider he hit was, obvious shock aside, excessively vexxed. And the other riders who started giving the bloke grief should all just have STFU. They didn’t help the situation at all, to the point that they could actually have made it worse. His apologies should have been only for the person he hit, not the circling drama queens/vultures looking for an excuse to vent.

He’s in the wrong, cos he rear-ended her.
Having said that, if you pick up your bike and hit me with it then expect me to take it off you and launch it as far away as possible. Crazy witch.

Ahh you forget about the effect of the mass on your momentum and how the brakes will have to work that much harder to bring the wheel to a stop? Assuming you are applying the same force at the lever the brakes will be less effective.

There are a few other refutations of this well worn misconception but this is the main one.

Stick to nursing.

no shortage of idiots in the asylum today then.

Stumpy – I bow to your figures but I find you can outbrake pretty well anything I have driven or ridden on a bike and have measured ( very roughly) braking in shorter distances than a car on tarmac. – certainly beating 1g easily.

It is suprising how quickly a bike can stop.

cheers stumpy, i’ll stick to nursing as that kinda maths on a friday morning makes my head hurt!

i’ve got a nearly new bike, brakes in good condition, pads bedded in, know how to use both the front and back brake effectively to stop with or without locking up and skidding depending on how childish i’m feeling… but i weigh about 14 1/2 stone (pure muscle of course 😆 ) and at 20mph if i had to brake suddenly i think i would’ve probably overshot the 5 meters with just reaction time alone!

if it helps i also have a heavy bike, tyres with big tread, 160mm rotor on the back and 185 on the front if anyone’s feeling geeky enough to do more complicated equations.

TJ, i propose that you film yourself riding at 20mph then when someone shouts stop you have to stop within 5 meters, thats the only way i can see this being settled.

either that or we can admit it doesnt matter in the scheme of things and have a cuppa tea and relax, after all its friday 8)

toys19 – Member

Ahh you forget about the effect of the mass on your momentum

No I am not. Of course more mass = more momentum

and how the brakes will have to work that much harder to bring the wheel to a stop? Assuming you are applying the same force at the lever the brakes will be less effective.

Of course the brakes will have to work harder thats my point – you can use more braking power- but you can apply them harder as you have more grip if you are heavier. You are assuming the same level of lever pressure – that would obviously mean longer stopping. I am saying you can use more lever pressure as you have more grip

Please =- read what I wrote

On gravel is grip not the limiting factor to the deceleration you can achieve – there is plenty of power in the brakes?

If you are heavier do you have more grip? as the loading on the tyres is greater?

TJ although the science is correct (friction is proportional to the reaction force), it doesn’t work like that in real life. I would be able to stop much quicker then you, for example.

I’m sorry, but you are wrong.

Real man – why not? why does the therory not apply in the real world?

You say you would be able to stop quicker than me? Why. I am 13 stone.

I am not saying you are wrong but I would like greater understanding of this and I can’t see a flaw in my reasoning.

TJ – like I say I’m a bit bored and thought I’d do a rough calculation – it’s probably a bit more complicated in real life!!
On the road you probably could stop in 5m, but on a gravelly trail – I’m not so sure. I always have to relate a distance to something for it to mean anything & apparently a SWB Transit is just under 5m long. I’m not sure I could stop off-road from 20mph in the length of a Transit van.

Technically his fault but she was being a total dick about it. WTFU!

I would have:

Bunny hopped her with massive awesomeness landed 180, flashed my six pack and asked her out for a drink.

He failed to do this so it’s his fault for being a bit sh!t

Thanks

Cornelius Reginald Xavier III

he stayed very calm after having a bike thrown at his face…. he must be a psych nurse.

surely its a bit of an unwritten rule that if you have to stop on a trail you pull to the side and get your bike off the track? big overreaction from her… and you cant spell overreaction without ovaries, ‘cos she’s a woman.

hang on, shouldnt she be in a kitchen? 😆

Of course the brakes will have to work harder thats my point – you can use more braking power- but you can apply them harder as you have more grip if you are heavier.

Ah so that’s why those 4×4 stop so quickly on icy roads..

Well, it is his fault to be fair, but given her reaction, I would have told her to ** off. It was a pretty lame fall and anyone who can jump to their feet and launch a bike at you isn’t hurt!

This is why I like a proII hub. People tend to hear them before you get close enough to shout trail.

Even though the whiny American psycho girl is more annoying than eczema, it’s still the blokes fault – he just didn’t leave enough room.

What if she’d fallen off? Or stopped because a baby Unicorn was frolicking on the trail in front of her, hmmn?

And why was he trying to pass her anyway? She had quite a nice bum, ’till he left tyre marks all over it.

This is why I like to ride little known natural singletrack either on my own or with folks whose capabilities I know and those who know my limitations.

I could imagine the wifie sueing the cameraman for whiplash injury and hissy fit trama compensation.

I liked the other video on the thread where someone did similar, and when he apologised, the girl he crashed into said, ‘it’s ok I was being a sloth’. 😀

Boo my work isnt letting me watch that. It does my swede in when people ride really close behind me though.

Deranged psycho harpies like her are the reason I have a little ping! bell on all my bikes, including mtbs. I’ve found it invaluable, from riding around London’s mean streets and canal towpaths, to the middle of nowhere. Weighs nowt, and is a polite and friendly way to let others know you’re there. Dunno if it would have been any use in this particular situation, but it’s been useful for me many a time.

beaucoup lollage

bloke’s “at fault” but the psycho harpy(TM) caused the crash and needs to **** shut up whining

(did anyone watch past the broken leg bit? – I had to stop)

somewhere online there is a video of sharki riding into the back of me after I punctured and he realised a bit late except he is swearing about hitting his balls on the stem and I’m laughing at him.

maybe I should have thrown my bike at him.

You say you would be able to stop quicker than me? Why. I am 13 stone.

I am not saying you are wrong but I would like greater understanding of this and I can’t see a flaw in my reasoning.

I’m considerably lighter then you.

And anyway, you have a tandem (I would assume). Which stops quicker, you on a solo bike, or the tandem? Using your logic, they should both stop in the same distance.

but realman. A tandem has a much longer wheelbase than a regular bike so surely given sufficient rider skill and good tyre/brake setup the tandem will stop significantly quicker as the back end wont lift up so fast. I often find, when my brakes actually work, that this is the real limiting factor. Unless of course its shitty mud or ..gravel.

I just realised im agreeing wtih your realman. Reading ftw.

That’s one angry woman, I get the impression she really didn’t want to be there. Yeah rider behind maybe could have swerved but he didn’t shit happens and no one was hurt but that reaction was way over the top. You have to remember there’s other riders and they may be behind you.

Its easier to do an emergency stop on the tandem as the rear doesn’t lift. On a solo to get the same deceleration you have to get your weight right back and low. You do have to be progressive with the front brake to load the tyre up tho or else it locks even on tarmac but load it up and the grip is amazing.

This is all assuming that there is plenty of brake force available. The tandem has sixpots on 203 discs.

So we agree momenteum is greater with more weight but grip is greater as well. therefore the braking distance should be the same for a light and heavy rider assuming that here is plenty of braking force available – ie you are not reaching the maximum capacity of the brakes.

Can someone explain why this is not right? Several people have said it don’t work like that but I don’t see why not.

*awaits enlightenment*

So we agree momenteum is greater with more weight but grip is greater as well. therefore the braking distance should be the same for a light and heavy rider

Lovely bit of pseudo-science there – isn’t that assuming that the greater momentum is completely cancelled out by the increased grip? A fairly big assumption.

Can someone explain why this is not right? Several people have said it don’t work like that but I don’t see why not.

Might be something to do with the fact that (ignoring momentum and forces) you have to convert a lot of kinetic energy into a lot of heat energy as quickly as possible. And with a lighter person, there is just a lot less kinetic energy to deal with.

chakaping – Member
Oof, looks like she was in a bit of a grumpy mood anyway. Maybe she hates MTBing but her boyfriend makes her do it.

PMT maybe? Can’t believe it hasn’t been mentioned in the previous three pages.

In response to the OP’s original question, I’d say it was a 70:30, he should have been able to react, but she stopped in such a stupid manner & place, almost makes you think she knew he was there!

Realman – “assuming plenty of brake power” – which on gravel we have – you skid or go over the bars before you run out of brake power / get fade do you not? single stiop from realistic speeds.

Grum – I agree its an assumption but is it unrealistic – is friction not directly proportional to the weight per unit area?

I love STW – video of an idiot mashing into the back of another rider, the other rider completely overreacting and going psycho… and you’re discussing physics. 😀

TJ you are forgetting that the friction between the brake pads and the rotor has nothing to do with the weight of the rider.

Why don’t you just go out and test it if you really don’t understand. Get a big heavy bag of bricks, try stopping with and without from the same speed.

S’funny how there’re so many riders on here but, rather than quoting trail etiquette, comparisons to motorway driving have been drawn. What’s that all about? Using your bike to clobber someone is way out of order.

Realman – I kno0w that – its not the limiting factor tho is it?

grip and going OTB are the limiting factors – or else the tandem would take twice as long to stop as a solo

Think about it.