I've always been of the opinion that attaching yourself to the pedals is more likely to result in landing on your head. Well not always - I formed that opinion after waking up one nice sunny afternoon in the middle of the road and no idea how I got there, and eventually coming to that conclusion.
Let's say you are doing 50km per hour downhill (abt 30mph)
That's 50,000m per hour, or
50,000/3,600m per sec = 13.89m per sec
According to [url= http://www.humanbenchmark.com/tests/reactiontime/stats.php ]the Human BenchMark site[/url] the median for clicking a mouse is 215 milliseconds. I suspect unclipping from spds would take a mite longer, but let's use that figure.
So distance travelled before unclicked is 13.89 x 0.215 = 2.98metres.
Let's assume you have hit something that stops your front wheel so now you are rotating around it.
Where will that 2.98m put your head by the time you unclick or let go the bars?
(I assume letting go the bars would happen about the same reaction time unless a decision was made to hold tight.)
Presumably it will be a complex action, and I'm trying to work out the scenarios.
1. Your body will pivot around the ankles until it hits the bars because your arms aren't strong enough to resist the forward motion, then the bike will pivot around the front axle if your brakes are on, or will it pivot around the contact patch? Anyhow maybe you have released by this point but your body is rotating.
2. Your arms are stiff enough to resist the impact (calculation suggests unlikely), so the pivoting starts immediately.
Anyone care to model this? I don't have the mathematical capacity - I've run out of fingers & toes on my Irish digital calculator (even assigning binary to them).
Are you really that bored.?
Like that*
*clicks fingers
30mph off road is bloody quick
my head hurts and i only read the first 2 lines
float - Member
30mph off road is bloody quick
I did say downhill.
But work it out for half the speed if you like.
makkag - Member
my head hurts and i only read the first 2 lines
Should have unclipped then 🙂
The chance of hitting something at 32mph that stops your front wheel dead are utterly minimal, unless it's jumped out at you as fast.
You won't be able to pull your hands off the bars due to the forces, but they will compress a bit.
I came off a road bike once, bottom of a gentleish hill
Seems the front brake came loose from the frame as I was slowing down, ran round with the wheel until the cable pulled taut and, err, stopped
I didn't even blink* in time, let alone unclip
* as far as I know - don't remember the crash at all
Let's assume you have hit something that stops your front wheel so now you are rotating around it.
I've always found looking where I was going prevents the issue from arising.
Op: ride, don't think - it all comes natural with some practice. Those who worry don't get there in a hurry - and all that. 😉
Er, is it me, but a scenario as described above would be just as bad on a bike with flat pedals as one with spds?
Just to push the point home; try imagining a situation at 50 kmh where your front wheel stopped with a flat pedal bike.... A running dismount at 30 mph?
Good luck with that Mr. purple bleeding face.
robsoctane - Member
Op: ride, don't think - it all comes natural with some practice....
Unlike many STWers I'm not a riding god with super powers. I do things like hit an innocent puddle at speed only to find that since I last went over it the river has scoured out the bottom, thus my wheel gets instantly stopped, or I get forced aside in a race and hit a rock offline with the same results, and other such incidents.
Thus I think about such things.
crikey - Member
Er, is it me, but a scenario as described above would be just as bad on a bike with flat pedals as one with spds?
That is one of the things I'm trying to work out. Stopping that quickly rarely has a comfortable outcome.
If the op wasn't a regular, I'd think this was a spam post that makes no sence what so ever.
i have 2 questions...
1. Why would you need to unclip in instant you hit something? nothing stopping you unclipping mid air.
2. If you hit something that stops your wheel instantly then as you say you will immediatley fly over the bars. What difference does it make if your clipped in? your head its still going to be doing 30mph at whatever stopped you.
Anyway, your very likley to wrench your feet out the clips (multi-release cleats anyone) if your doing 30mph and your bike is doing 0mph. Much more safe than toe straps of old.
[i]Thus I think about such things. [/i]
We really, really need a shaking head at the silly person smiley.
Manual the puddle.
What forces you off line in a race? Is the race the puffer?
STATO - Member
1. Why would you need to unclip in instant you hit something? nothing stopping you unclipping mid air.
2. If you hit something that stops your wheel instantly then as you say you will immediatley fly over the bars. What difference does it make if your clipped in?
1. That's the point, you react a given time after the incident so you are clipped in until that point.
2. I'm trying to work out how having your legs attached affects the position of your body in that 215 milliseconds.
As a rough model, I'm considering the body as the sum of 3 hinged masses, head, thorax, legs (ignoring arms for now).
You bloody loony.
Think about the weights involved and where those weights are. You are a big blobby 70-80-90 kgs and you will revolve around your stopped front wheel whether you are clipped in or not.
What happens in those 215 milliseconds makes no bloody difference at all.
You are either dim as a dim thing or trolling at the very limits of trollability.
cynic-al - Member
Manual the puddle.
What forces you off line in a race? Is the race the puffer?
Obviously if you know there is an existing danger you'll approach it differently.
I go offline to allow faster riders past and sometimes don't see the hidden traps.
However I'm talking about a theoretical situation - can we concentrate on what happens after, not the lack of prescience/skill/luck that causes it?
That's offensive crikey.
I'm not trying to prove any point. I'm trying to work out the trajectories.
I'm interested in why and how things happen.
It's not offensive; it's accurate.
the force will unclip you and you wont really have enough time to react
In the scenario you decide i doubt there is very much difference between clipped in and flats as you will either
1. be catapulted off the bike at great force
2. rotate OTB instantly and have a face ground interface
I go for one if the wheel stops dead as the more likely
Flats may [ probably do] let you get your feet off slightly quicker but with those forces i doubt there is any real tangible difference
Last time it happened to me I was doing about 10 mph and face planted into a puddle whilst still holding onto the bars and clipped in.
Was still laughing about it half an hour later!!
The chance of hitting something at 32mph that stops your front wheel dead are utterly minimal, unless it's jumped out at you as fast.
I cut a really fast corner on dartmoor once chasing sharki down.
Perfect granite wheel trap hidden in the grass stopped me dead in my tracks, had perfect handlebar bruise across my chest and ended up in a bush on the other side of the trial.
epicyclo - Member
robsoctane - Member
Op: ride, don't think - it all comes natural with some practice....
Unlike many STWers I'm not a riding god with super powers. I do things like hit an innocent puddle at speed only to find that since I last went over it the river has scoured out the bottom, thus my wheel gets instantly stopped, or I get forced aside in a race and hit a rock offline with the same results, and other such incidents.Thus I think about such things.
That's where you are going wrong - don't THINK, feel!
Honestly, you fret too much! 🙄
crikey - Member
Thus I think about such things.We really, really need a shaking head at the silly person smiley.
[img] 
[/img]
Hmmm, bit too stern that one. I'm thinking more of a kindly old lady shaking her head at the silly boy kind of thing...
this is where eggbeaters would be good, the force would probably snap the axle
Your feet will be pulled out of the pedals with the force of the initial impact.
I've no idea of the forces involved but I've come off my bike loads of times and always come out the pedals without me doing anything. It's never caused me any issues.
The vast majority of mtbers ride clipped in nowadays, if they caused harm during accidents we'd know about by now.
How quickly can you unclip?
I doubt theres more than 1/10 second difference between clip and no clip getting my foot off the pedal.
God unclips me... it must be some kind of higher force anyway because I never have to think about doing it... it just happens.
The original question 'how quickly can you unclip?' is wrong. It should be how quickly can you put your foot down if you need to? And that is exactly the same whether you are clipped in or not as its the same movement. If you are nervous clipped in just practice until it makes no difference. Stop overthinking and start enjoying it...
My last crash was a high speed lowside on flats and was sliding along the ground with my bike before I had even had a chance to move my feet.
I see flats as more of a low speed benefit, being able to dab a foot quickly without having to unclip seems more useful and frequent than the high speed stuff.
I've run clipless for many years with regular (not multi-release) cleats. I can't ever recall a crash where I remained clipped in. Since I can't claim to have cat like reflexes, I have to assume that the cleat/pedal system has been designed to release if sufficient force is applied even in directions other than that used to unclip.
If you are really concerned about it, use multi-release cleats or dial the release tension down to the minimum.
The answer is: "Imhotep is invisible".
I cut a really fast corner on dartmoor once chasing sharki down.Perfect granite wheel trap hidden in the grass stopped me dead in my tracks, had perfect handlebar bruise across my chest and ended up in a bush on the other side of the trial.
I have [i]never[/i] had so many OTB crashes anywhere, as I have riding dartmoor. If it's not a granite lump it's a bog or as it was yesterday: an innocent looking patch of mud, just like the others I'd ridden through, but Hub-deep as it turned out.
Are we talking 29er clipped in OTBs? The larger circumference will give you that matrix neo slow motion type reflex... you not only will have unclipped, you will also had time to pull the uzi from your leather padded shorts and have shot 2 hikers before doing a forward front somersault and landing drop knee style. You also need to determine what tyre pressure you are running and whether tubeless or not.
I don't know how you guys dream up these crazy scenarios.
I have to congratulate the OP for hand wringing of the highest order, having come off a bike at those speeds I can honestly say my choice of pedal was the least of my concerns. What tyres for bed wetting anyone?
Can I just point out that for at least 10 months of the year where I live that the mud is sufficient to allow a maximum speed of approx 4 mph only? If you're that concerned, maybe move to a mudfest part of the country.
Oh and in answer to your question, I reckon when things do suddenly go pear-shaped at speed I can unclip and fall off in less than a nanosecond.
Does that help?
I'll always remember a mate at school was showing off his wheelie skills. He hoofed the front wheel up, began to pedal but over-rotated and fell off the back. However, he kept his riding position exactly and the bike was on top of him, supported by his hands on the bars and feet on the pedals. He used flats.
I unclip fast enough not to notice, like blinking.
It happens as an unthinking response now.
I fall off a lot, try to do jumps, gaps etc, ride Chicksands / Alps etc. I dont remember landing still clipped in.
How fast is this:
1) Unless they are bastid tight, clipless pedals unclip rather easily against anything other than normal pedalling up-and-down forces. Given that clipless pedals are like small ski bindings, which (hopefully) undo if you fall over 'wrong', you have to be doing a fairly dead-on straight OTB or falling off the back to not be tugging your cleats out of the pedals at a sufficient angle for them to disengage with a realitively low force.
2) I fell over clipped in twice in 2001 when I first got clipless pedals. I have come of plenty of times since then and never been attached to the pedals at the end of it. I don't know if the fraction of a second longer it must take to twist out of the pedal was a factor in these crashes ie whether I could have ridden out of them on flats, but I can't remember even thinking about unclipping for many years, whether that is stopping at the lights, or suddenly having to jab a foot out on some really tricky trail, it just happens, even when the bike stalls and is at a virtual standstill.
3) Steve Peat and Greg Minnaar. I bet they can undclip quickly at high speed.
The more you use spd's the faster you will unclip. It becomes a subconscious reaction over a period of time. For me it was about 6 months of slow speed topples. 2 years in, I am usually unclipped before any thing hits the ground.
On the speed issue, it is rare do more than 30 mph downhill. We do have a bridalway on our regular route which goes down a steep hill with small steps made from railway sleepers every 20 feet or so. Top speed recorded down there was 34.9 mph but is always over 30mph. I am no riding god and it used to scare the crap out of me when I started riding spd's. I quickly realised that having my feet clipped in made it easier so I relaxed, was less tense and found it better than with flats.
My advice is to practice with spd's until unclipping becomes subconscious and stay away from mathematical calculations with more variables than you can make sense from.
Thanks for the sensible replies from some folks, especially the last few today. I'm amazed at the reaction, personal attacks, accusations of being dim, bed-wetting, nervousness, etc. I suspect I would be treated more politely if I walked into a mosque with a burning koran in my hands.
So an apology - I should have realised asking a technical question would bring out the dribbling brain deficient trolls from their mbuk caves, and sorry if this question has hurt your head.
Came off my road bike a couple of weeks ago. All I know is when the crash started, I was clipped in and when I was lying on my back in the middle of the road after escaping over the handlebars, I was no longer attached to the bike. At what point my feet became unclipped from the pedals, I truly have no idea.
All I know is the bike was about 20ft away from me when I collected everything.
Well this would be the result if you don't get it right!!
http://www.rootsandrain.com/photos/235002
From yesterdays mini downhill at FOD.
For the purposes of balance, there was a great (presumably 'set up') photo in Bryceland's column in Dirt a while back, where he talks about trying spd's: picture of him upside down with feet still clipped in and bike wheels up in the air. 😀
Anyway, your very likely to wrench your feet out the clips (multi-release cleats anyone) if your doing 30mph and your bike is doing 0mph. Much more safe than toe straps of old.
The only thing faster than me 'panic-unclipping' is me 'accidentally unclipping' with multi release cleats. Unpredictable-Death Cleats more like...
Steve Peat and Greg Minnaar. I bet they can undclip quickly at high speed.
I am pretty sure both of them have mentioned not being able to unclip contributing to crashes and incidents over the last few years, as have many elite dh racers.
Most clipped riders claim to be able to unclip instantly, and yet most of their crashes / excuses involve not being able to unclip quickly enough.
I had the misfortune of seeing a friend of mine do something along the lines of what the op is describing - he went otb on a very fast section of trail. A rock deflected his wheel which dug in like an anchor and catapulted him forward, as he flew forward he brought the bike with him and it acted like a pendulum flipping him off the trail and 30ft down a bank. He broke a few ribs and fractured his wrist if I recall. He was overtaking me at the time and the effect was as if a bomb had gone off underneath and blew him off the trail, it was savage.
Impossible to say whether his injuries would have been substantially less had he been riding flats but the crash would have been a lot less spectacular.