Peds walking out in front of you

[JBB]

Bugger. Riding home tonight (at a moderate speed) a woman stepped off the pavement right in front of me without looking. I braked and went over the handlebars. I ended up on the floor and, despite the fact that I had collided with her - she broke my fall! - she just walked away. A couple of lads came to ask if I was all right, and a couple of cars stopped to check if I needed help. Fortunately, I seem to have just bruised an elbow and wrenched my knee - but here's the thing, it was the knee I had replaced just a couple of months ago. Lots of ice this evening and more of the same over the next few days are in order, I reckon. Could have been a lot worse.

Still shaken, but feeling lucky, and amazed that she could just walk away like that without even turning around to see if I was all right.

Hi Rob - only just read this  . Are you OK?

[Jacomus]

Bikesdontfloat and Jaded's posts above got me thinking about last nights close call.

That was one rainy commute!

At Bank, a chap crossing the road commented "solid beard, very solid mate"

I had a good run to London Bridge, just after the station I tested the limits of Brompton brakes in the wet. A chap on a hybrid looked comfortably stationary and not intending to pull out to the right. I was approaching quite fast, spotted him and scrubbed a little speed off. With about 2 metres to go, still without a single glance over his shoulder, he pulled away. Que the classic 'whoa-whoa-whoa!' much braking effort and not much braking result! I bumped him very gently, he apologised and neither of us actually quite stopped rolling.


I was off my game for the rest of the journey and hit a few manhole covers. Not something I'd normally make a habit of, especially in the wet.

Ive done a bit of playing around with a speed-distance-time calculator, and found that something is wrong with my memory off it.

I know that I was riding at 9mph after scrubbing a little speed off and I still had my fingers on the brake levers and that I was dragging the brakes lightly.

My estimate of 2.5 metres can't be correct. 

If we are generous regarding my reaction time by calling it 1sec as I was fully prepared to drop the anchors, he must have pulled out when I was at least 8 metres away.

[jsabine]

My estimate of 2.5 metres can't be correct. 

If we are generous regarding my reaction time by calling it 1sec as I was fully prepared to drop the anchors, he must have pulled out when I was at least 8 metres away.

I bet it felt like 2.5m though - or even 1.5 ...

Pedestrians move slowly - and if one appears to materialise suddenly in your path then then that is entirely due to you attempting to ride too fast and too close to them. We rightly expect drivers to overtake us with care and leave us sufficient space to swerve to avoid unexpected objects or to fall off - we need to excercise the same care when we are passing more vulnerable users than ourselves. 

If you can't see something is not there/jumping out - assume it is. Drive/cycle accordingly.

Drive like that on your test though, and your "failure to make progress" will ensure a fail. So instructors instruct you to make progress. So making progress becomes ingrained.

[Robh]

Bugger. Riding home tonight (at a moderate speed) a woman stepped off the pavement right in front of me without looking. I braked and went over the handlebars. I ended up on the floor and, despite the fact that I had collided with her - she broke my fall! - she just walked away. A couple of lads came to ask if I was all right, and a couple of cars stopped to check if I needed help. Fortunately, I seem to have just bruised an elbow and wrenched my knee - but here's the thing, it was the knee I had replaced just a couple of months ago. Lots of ice this evening and more of the same over the next few days are in order, I reckon. Could have been a lot worse.

Still shaken, but feeling lucky, and amazed that she could just walk away like that without even turning around to see if I was all right.

Hi Rob - only just read this  . Are you OK?

Hi Julia, I think I was more shaken up by it than anything physical. The elbow was sore for a day or so but the knee seems OK.

[Diver300]

Ive done a bit of playing around with a speed-distance-time calculator, and found that something is wrong with my memory off it.

I know that I was riding at 9mph after scrubbing a little speed off and I still had my fingers on the brake levers and that I was dragging the brakes lightly.

My estimate of 2.5 metres can't be correct. 

If we are generous regarding my reaction time by calling it 1sec as I was fully prepared to drop the anchors, he must have pulled out when I was at least 8 metres away.

The highway code assumes 0.675 s reaction time. I think that includes the time taken to release accelerator and press the brake. If you were already dragging the brakes, and you had already considered the possibility of him pulling out I would guess around 0.3 s.

9 mph is 4 m/s, so that would only be 1.2 m

I would estimate 0.5 g stopping. Cars can manage about 1 g, and the highway code allows for 0.67g.

From 4 m/s, the distance would be 1.5 m at 0.5 g

Total would be 2.7 m

Obviously that figure is heavily dependent on the estimates for reaction time and deceleration, and the accuracy of the speed recorded.

[Kim]

0.5g sounds optimistic for stock Brompton brakes in the wet.  Even with the post-2013 levers.  That said, if he was already dragging them, the rims may have cleared.

(I fitted mine with Kool Stop Salmons.  Much improvement in wet weather performance, though it still stops like a Brompton.)

[Diver300]

I feel that a Brompton deceleration test is in order. I need to molish a acceleration logger.

I don't have much confidence in my estimate of 0.5 g, and I wouldn't be surprised if best deceleration was a quite a bit worse.

However, 8 m for reaction and stopping from 9 mph looks very unlikely. It would need the deceleration to be only 0.11 g, and I would think that a Brompton could do significantly better than that.

If the deceleration were 0.11 g, the time from 9 mph to stationary would be around 3.5 seconds, and even in the wet I am sure I can do a lot better than that on my Brompton.

[LittleWheelsandBig]

It is fairly easy to lift a Brommie back wheel under braking (with decent hand strength), so 0.5G isn't too hard to achieve.

[Cudzoziemiec]

I had a bloke walk across a narrow street in front of me this morning, from left to right. He didn't look in either direction but was I was going slow enough (up hill) that it didn't matter. Except when he was 2/3 of the way across, he then turned round and went back, still not looking. Still wouldn't have been too much of a problem — except of course it's raining and the huge umbrella he was carrying effectively blocked the whole available width, parked car to parked car, of the narrow street.

[Kim]

I feel that a Brompton deceleration test is in order.

I tried this unscientifically a few of times on yesterday's ride.  Bromptom with damp rims from a convenient puddle, travelling at 9mph on drying road.  2014 brake levers, Kool Stop salmon pads.  Mk 1 Kim grabbing as much front brake as possible (While on a good day I can apply a gripping force of at least 25kg^[1] with my right hand, the ergonomics are very much the weak point in this setup - I find the levers hard to reach, as the fold necessitates they point almost vertically downwards, and there's a lump of twist shifter in the way).

It would consistently stop in about two bike lengths.  At no point could I lift the rear wheel.


_{[1] According to barakta's physioterrorist's grip meter, which approximates a 4-finger MTB brake lever.  I didn't pick the units.}

[LittleWheelsandBig]

My centre of gravity is higher, helping with applying lever force and worsening pitch-over. Lifting a Brommie rear wheel isn't too tough, albeit it means pulling hard.

[ian]

I will say that turning out of my drive and down the 25% hill on the Brompton generally ensures that it's not just the brake levers that are being clenched.

[Kim]

I've done a couple of double-chevron descents on the Brommie.  Very carefully.  Hand cramps were involved at the bottom of one of them.

That said, it's at least as good at stopping as the low-end mountain bikes I used to ride as a kid.  I've just been spoiled by bikes with discs and well-adjusted V-brakes.

[Jacomus]

Aye, Lady Bertie doesn't stop with the same kind of enthusiasm that Spesh does. Although Spesh's front rotor is almost the same size a Brommie wheel Also, i'm not all that sure how much I'd like to see how much the stem would flex under the force of proper brakes.

[mattc]

If you can't see something is not there/jumping out - assume it is. Drive/cycle accordingly.

Its not rocket science.

Darn right - if we'da thought like that, we werent ever gonna git to the moon!

[Mr Larrington]

That proves Apollo 11 was a fake.  Brakes were crap in the 60s.