Mysterious falling off bike

Commuting, Day rides, Audax, Incidents, etc.
heathfield55
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Joined: 24 Jun 2018, 10:51pm

Mysterious falling off bike

Postby heathfield55 » 18 May 2019, 1:41pm

The other day I was road testing my new Gravel Bike on reasonable tarmacked country road , dry conditions (30 mm tyres), in good light conditions and was abruptly unsaddled after I hit what I thought must have been a pothole or similar. I was doing 20mph at time, so I was fairly bruised and cut as I went face first onto tarmac, fractured my hand too. its the first major accident I have had in 40 years of cycling so it has unnerved me, especially as when I checked the accident spot after and there were no potholes. my only theory is that must have hit a largish pebble that took my front wheel although there were none in sight. I only weight abt ten stone and my tyre pressures were rock hard. Hhas anyone else out there had such a misfortune ? Any theories on how it might have happened. Just wondering whether my tyre pressures are too hard. Cheers

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gaz
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Re: Mysterious falling off bike

Postby gaz » 18 May 2019, 1:56pm

Sorry to hear of your off. I'll not speculate on the cause.

heathfield55 wrote:I only weight abt ten stone and my tyre pressures were rock hard. ... Just wondering whether my tyre pressures are too hard.

"Rock hard" needs a definition before consideration can be given as to whether it is "too hard".
Hand wash only. Do not iron.

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Cugel
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Re: Mysterious falling off bike

Postby Cugel » 18 May 2019, 3:52pm

heathfield55 wrote:The other day I was road testing my new Gravel Bike on reasonable tarmacked country road , dry conditions (30 mm tyres), in good light conditions and was abruptly unsaddled after I hit what I thought must have been a pothole or similar. I was doing 20mph at time, so I was fairly bruised and cut as I went face first onto tarmac, fractured my hand too. its the first major accident I have had in 40 years of cycling so it has unnerved me, especially as when I checked the accident spot after and there were no potholes. my only theory is that must have hit a largish pebble that took my front wheel although there were none in sight. I only weight abt ten stone and my tyre pressures were rock hard. Hhas anyone else out there had such a misfortune ? Any theories on how it might have happened. Just wondering whether my tyre pressures are too hard. Cheers


A large piece of loose stone in the road can, if you hit it the right (i.e. wrong) way set you skittering sideways. If the tyre hits one side of such a stone, the stone lifts you a bit then pings out sideways, sending you and the bike the other way. If you're off the the ground i' the front wheel because the stone has lifted you a bit before pinging off, you might land whilst still going sideways. If the road surface is loose, having an adverse camber or otherwise not grippy, the front wheel slides from under you and down you go.

All this can happen in an instant. A hard tyre (over-inflated) tends to exacerbate the effect as it fails to conform to the stone so gets lifted a bit more; and a hard tyre is also less grippy as the contact patch with the road will be small.

That's my guess. based on many a jigging about after such a hit .... but I have large properly-inflated squishy-grippy tyres and the ability to jink about a bit when the bike is naughty, so don' fall off. :-)

Cugel

gbnz
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Re: Mysterious falling off bike

Postby gbnz » 18 May 2019, 5:17pm

heathfield55 wrote:The other day I was road testing my new Gravel Bike on reasonable tarmacked country road , dry conditions (30 mm tyres), in good light conditions and was abruptly unsaddled


I had my first "off" in 30 years a couple of years back, the bike simply flipping onto it's side. It was harvest time and my immediate inspection identified a small diesal spill (NB. On returning to the spot later I noted that AN Other had covered the spot with sand). I was lucky as if I'd been coming down off the moor, I'd have been doing 33mph+; as it was I had a full load of shopping on the bike and was probably only doing 12mph, so damage was limited to a front tooth being knocked back and skin taken off the chin/jaw/elbow

roberts8
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Re: Mysterious falling off bike

Postby roberts8 » 18 May 2019, 7:10pm

I have no experience of disc brakes but if the bike was kitted out with them is there a chance of a small sone flipping up, jamming and causing the wheel to stop moving. I probably sound a real Luddite but just a thought.

slowster
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Re: Mysterious falling off bike

Postby slowster » 18 May 2019, 8:44pm

When you say there were no potholes, were you looking specifically for a broken road surface? In my experience even a relatively shallow depression in an unbroken road surface can present a similar hazard, especially if the curve of the depression matches your wheel. In that situation once the wheel has dropped into the depression, it may not then roll smoothly over the far edge to exit the depression. In other words, even though the edge of the depression may not be a sharp corner, it can still feel as if the front wheel has hit one and cause a crash. Because the road surface is unbroken such depressions are difficult to spot, so are more likely to catch a rider unawares.

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Wanlock Dod
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Re: Mysterious falling off bike

Postby Wanlock Dod » 18 May 2019, 9:07pm

Something slippery on the road surface perhaps?

Postboxer
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Re: Mysterious falling off bike

Postby Postboxer » 18 May 2019, 9:28pm

Badger attack!? Or other weighty animal, seems unlikely you wouldn't see it though but perhaps not impossible.

pwa
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Re: Mysterious falling off bike

Postby pwa » 18 May 2019, 10:00pm

roberts8 wrote:I have no experience of disc brakes but if the bike was kitted out with them is there a chance of a small sone flipping up, jamming and causing the wheel to stop moving. I probably sound a real Luddite but just a thought.


Might be worth a forensic look at the rear of the front caliper to see if there is any scratching where a bit of something may have been brought in by the disc, though it seems unlikely. The disc itself might show signs if that is the case.

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NATURAL ANKLING
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Re: Mysterious falling off bike

Postby NATURAL ANKLING » 18 May 2019, 10:19pm

Hi,
I had that same once.

Sunny day, clear newish road.......abruptly I was on the ground, I was traveling straight along a straight road, a dual carriage way no less.
No traffic at all, rim brakes and never before and never since had a problem with a locking brake or such.
I once carried a stick in my hand and when braking the stick went through front spokes.................. :( :oops: :evil:
landed in gutter with head a few feet from a lamp post.

Anyway, back to my incident, in saddle both hands on the bars, no debris no nothing even gravel on the tarmac, I live in wonder what happened.
It can happen, anything is possible.

Felt like a brick, a stone would pop out and with rear tyre you feel it too.
Must of been front wheel.
Abrupt as black ice, I know what the feels like.
If You Don't Try You Don't Do.....Don't Do You Don't Get...I'm Still Trying....Well Very..
You'll Find Me At The Top Of A Hill...............Somewhere...After Dark..

heathfield55
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Re: Mysterious falling off bike

Postby heathfield55 » 19 May 2019, 12:06pm

Thanks everyone for your theories. I do have disc brakes so will check discs for any evidence of stone jamming. I will revisit accident spot when my wounds have recovered and study a bit more, there was quite of bit of blood there to mark spot ouch... on a lighter note during all the haze after the accident I later realised that I left my Strava app running. To my horror (I think that’s the right word) my ride was accredited with all sorts of world time records, with a top speed of 51 mph. This was explained by the fact that after I was treated by paramedics a very kind gentleman gave me and my bike (which barely had a scratch incidentally) a lift home in his BMW people carrier with Strava clocking up crazy stuff !! Needless to say I deleted the ride on Strava now as I do have a conscious lol....

tim-b
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Re: Mysterious falling off bike

Postby tim-b » 20 May 2019, 5:29am

Hi
Sorry to mention it, but if there isn't a road surface / bike problem, is there a medical reason?
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

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Cugel
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Re: Mysterious falling off bike

Postby Cugel » 20 May 2019, 8:29am

heathfield55 wrote:Thanks everyone for your theories. I do have disc brakes so will check discs for any evidence of stone jamming. I will revisit accident spot when my wounds have recovered and study a bit more, there was quite of bit of blood there to mark spot ouch... on a lighter note during all the haze after the accident I later realised that I left my Strava app running. To my horror (I think that’s the right word) my ride was accredited with all sorts of world time records, with a top speed of 51 mph. This was explained by the fact that after I was treated by paramedics a very kind gentleman gave me and my bike (which barely had a scratch incidentally) a lift home in his BMW people carrier with Strava clocking up crazy stuff !! Needless to say I deleted the ride on Strava now as I do have a conscious lol....


Ah ha! Here is another possible factor in the crash. Were you striving so hard for the strava that you took a speed-risk of some kind that lack of strava-pressure might have seen you be more circumspect? I have seen this syndrome too many times in certain lads. There was even one who killed himself descending The Trough of Bowland far too fast in an effort to get the Kom thereupon!

Of course, this is an extreme and outside chance, but ....?

Cugel

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RickH
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Re: Mysterious falling off bike

Postby RickH » 20 May 2019, 1:56pm

heathfield55 wrote:... on a lighter note during all the haze after the accident I later realised that I left my Strava app running. To my horror (I think that’s the right word) my ride was accredited with all sorts of world time records, with a top speed of 51 mph. This was explained by the fact that after I was treated by paramedics a very kind gentleman gave me and my bike (which barely had a scratch incidentally) a lift home in his BMW people carrier with Strava clocking up crazy stuff !! Needless to say I deleted the ride on Strava now as I do have a conscious lol....

On the Web version of Strava you can trim (crop) rides of extraneous sections rather than delete them completely.

heathfield55
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Re: Mysterious falling off bike

Postby heathfield55 » 21 May 2019, 7:44am

Ah ha! Here is another possible factor in the crash. Were you striving so hard for the strava that you took a speed-risk of some kind that lack of strava-pressure might have seen you be more circumspect? I have seen this syndrome too many times in certain lads. There was even one who killed himself descending The Trough of Bowland far too fast in an effort to get the Kom thereupon!

Of course, this is an extreme and outside chance, but ....?

Cugel


You are quite right Kugel. In fact I have already made the decision to take out the competitive bit from Strava in future. I am a fit 64 yo but there comes a time to slow down and take in the scenery. I don’t want to go head first over top of bike at 20 mph again, not fun. I probably got off quite lightly this time, fractured thumb, numerous cuts and bruises , however when I turned in bed this morning,I got a loud crack from my ribs with some pain so it’s back to hospital to get that checked out.