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Post crash analysis observation

Old 06-01-20, 10:13 PM
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Post crash analysis observation

i crashed on the Mup yesterday at sun set. it happened at this place where Mup tramsition into sidewalk. there are obsticles ( bollards) on the ground to force cyclists to slow down. i felt like someone yanked the handlebar out of my hands...then felt the front wheel go sideways...then i was over the handlebar and on the ground...knee bleeding.

not sure what happened. i look back and only unusual thing i saw was there was 3 bumps on the ground where plastic bollards used to be. i guess i didnt see this bumps. but these bumps were not big enough to cuase my front wheel to go sideways. so something else is going on.

i had changed the handlebar twice, few weeks ago. the bike is a bolt-upright cruiser geometry with heavy swept back handlebars. i replaced the handlebar with one thats 10 degree sweep, 58mm wide...and used a 80mm stem instead of the original 30mm...so that i could lean forward a alot more.

right after this first modification, i noticed the bike felt very tweetchier. i forced myself to ride this for a week. after a week, i got used to it. but decided, it was too tweetchy for the Mup i had to ride on daily basis.

so....i replaced the h bar again...this time with a 45 deg sweep and 55mm wide. the result was much less tweetchy than the 10 deg bar...but theres still some. and i am back more upright.

i ride down these steep long ramps everyday. with 45 d bar and 80 stem, it still feels tweetchy enough that i dont dare take one hand off.

i recall with the original heaily swept bar and 35mm stem, i could ride down rhese ramps one hand easily.

one last observation about the 45 deg sweep. i felt the angle puts yur grip in a very weak position. there were instances before where my front wheel hit a small bump and i felt my hand almost was pulled off the grip. i dont think i would have crashed if i was using a 10 deg bar. so there was a tragic consequence. but i am lucky i did not hit my head or break any bones.

the bumps looks like these...but with the veritcal piece missing.


Last edited by mtb_addict; 06-01-20 at 10:39 PM.
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Old 06-01-20, 11:41 PM
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Man I feel for you. Sounds like a harsh shock.

I went between some bollards a couple days ago, I had to push off of one to keep my line, even at slow speed.

How's the bike?
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Old 06-02-20, 12:13 AM
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DANG, that was some dissection, OOPS - post crash analysis observation. Good to read that you made it through relatively "unscathed."


Post crash analysis observation of my crash 5 weeks ago yesterday 4/27/2020 at 1:25AM >>>>


At 150lb MAMA Wild Hog ran up and side swiped me, I went off MUP, front tire dug in, got flipped off the bike, still smarting from cracked scapula + 2 cracked ribs + punctured lung + JUST FOUND OUT YESTERDAY that I also have shoulder damage.
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Old 06-04-20, 03:52 AM
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the bike is a tank...no damage at all. just twisted the steering stem out of alignment.

i realized later my right shoulder got messed up. it hurts a little when i put pressure on it.

after two days, the knee hurts more than before. it is too painful to walk down stairs now.
i wonder if it is infected.
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Old 06-04-20, 04:41 AM
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Those sections that support the bollards could easily deflect a front wheel if hit on the wrong spot with the bollards removed. With the bollards removed I'd considerthem a bicycling hazard.

On a trail I rode sometimes they decided to put up a barrier gate but supposedly left enough room on the right side(as you are approaching it form the west side) but they also put in another steel post. Unfortunately that post wa hidden by brush/leaves and when I moved right to miss the barrier I hit that steel post. A few scrapes becuase I was knocked down and my front fork was pushed sideways a bit.

Some infrastructure seems to NOT be designed with bicyclists in mind and in low light it can be downright dangerous.

I'm glad you're okay.

You might want to mention your experience to your local council or whomever is responsible for those bollards. It might prevent it from happening to some other poor soul.

Cheers
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Old 06-04-20, 04:45 AM
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Front wheel washout has been what's taken me down the last 3 times I have been down on the road. Different reasons for the washout each time. If I understand what you are saying correctly, those bollard bases could definitely wash out a front wheel.
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Old 06-04-20, 07:00 AM
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Sorry about your crash.
I'm not 100% sure that I understand your handlebar changes, however, if nothing else changes other than moving your hand position forwards, this really should make the bike more stable. Moving the bars back with back sweep usually makes them twitchier.
The only thing I can think of is that you have changed the headset adjustment when you changed the bars.
How well adjusted is the headset and what type is it? A-head or quill?
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Old 06-05-20, 03:19 PM
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Originally Posted by AnthonyG
I'm not 100% sure that I understand your handlebar changes ... this really should ... etc.
While you are correct in theory--and there is probably a complex combination of specific factors at play that the OP describes as "swapped bars & stem, handling changed"--direct experience trumps theory.
It's very clear that on this bike, with a long stem, flatter bars = twitchier handling and worse hand grip.
Conclusion: put the original stem and bars back on, they make the bike work MUCH BETTER.

(If you're feeling adventurous, try the 10 & 45 degree bars with the original stem.)
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Old 06-05-20, 06:25 PM
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Originally Posted by theDirtyLemon
While you are correct in theory--and there is probably a complex combination of specific factors at play that the OP describes as "swapped bars & stem, handling changed"--direct experience trumps theory.
It's very clear that on this bike, with a long stem, flatter bars = twitchier handling and worse hand grip.
Conclusion: put the original stem and bars back on, they make the bike work MUCH BETTER.

(If you're feeling adventurous, try the 10 & 45 degree bars with the original stem.)
What I'm trying to ascertain is, is the headset properly adjusted. A poorly adjusted headset will make the steering VERY unstable. Either too tight or too loose is very bad for the steering and general stability.
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Old 06-05-20, 08:54 PM
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Originally Posted by mtb_addict
i crashed on the Mup yesterday at sun set. it happened at this place where Mup tramsition into sidewalk. there are obsticles ( bollards) on the ground to force cyclists to slow down. i felt like someone yanked the handlebar out of my hands...then felt the front wheel go sideways...then i was over the handlebar and on the ground...knee bleeding.

not sure what happened. i look back and only unusual thing i saw was there was 3 bumps on the ground where plastic bollards used to be. i guess i didnt see this bumps. but these bumps were not big enough to cuase my front wheel to go sideways. so something else is going on.

i had changed the handlebar twice, few weeks ago. the bike is a bolt-upright cruiser geometry with heavy swept back handlebars. i replaced the handlebar with one thats 10 degree sweep, 58mm wide...and used a 80mm stem instead of the original 30mm...so that i could lean forward a alot more.

right after this first modification, i noticed the bike felt very tweetchier. i forced myself to ride this for a week. after a week, i got used to it. but decided, it was too tweetchy for the Mup i had to ride on daily basis.

so....i replaced the h bar again...this time with a 45 deg sweep and 55mm wide. the result was much less tweetchy than the 10 deg bar...but theres still some. and i am back more upright.

i ride down these steep long ramps everyday. with 45 d bar and 80 stem, it still feels tweetchy enough that i dont dare take one hand off.

i recall with the original heaily swept bar and 35mm stem, i could ride down rhese ramps one hand easily.

one last observation about the 45 deg sweep. i felt the angle puts yur grip in a very weak position. there were instances before where my front wheel hit a small bump and i felt my hand almost was pulled off the grip. i dont think i would have crashed if i was using a 10 deg bar. so there was a tragic consequence. but i am lucky i did not hit my head or break any bones.

the bumps looks like these...but with the veritcal piece missing.

If only you had more camera angles...

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Old 06-05-20, 10:27 PM
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Like changing the door hinges after you slammed your finger in the door
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Old 06-07-20, 07:48 PM
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Originally Posted by AnthonyG
Sorry about your crash.
I'm not 100% sure that I understand your handlebar changes, however, if nothing else changes other than moving your hand position forwards, this really should make the bike more stable. A-head or quill?
Originally Posted by theDirtyLemon
While you are correct in theory--and there is probably a complex combination of specific factors at play that the OP describes as "swapped bars & stem, handling grip.
.

Spending a few days indoor to heal my wounded knee, gave me a lot of time to reflect and do research.

Regarding the hbar forward/aft positioning, using a longer (forw/aft) stem in my case, puts my hand closer to the axis of rotation (See foto below.). According to Sheldon article on English Roadsters, this change will majke steering less stable.


This is the old 40mm stem (more aft). My hand would be behind the rotation axis.


But the current 80mm stem (more forward), looks like this.


Last edited by mtb_addict; 06-08-20 at 03:56 AM.
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Old 06-07-20, 08:04 PM
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Regarding the steering bearing tighteness...
my steer bearing is perfectly adjusted...no freeplay...no drag.
but, i guess i can try to tighten the bearing a tad more...maybe a bit of drag will help.


one more thing, is that with the more forward stem, putting my body weight on the bar will make it feel less stable. for example, if i coming down steep ramp and put my body weight on the bar, it will feel wobble. it was scary, the first time i felt it...it was a steep ramp down a 4 story garage.

Last edited by mtb_addict; 06-07-20 at 08:36 PM.
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Old 06-07-20, 08:11 PM
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Another thing I recall is that few weeks ago, I had a close call. I didnt think much about it at the time.

I was riding at slow speed. There was nothing on the ground but smooth pavement. I was trying to make a tight turn, and all of sudden, it felt like the hbar wants to pull out of my hands. It was such a wierd feeling I never felt before. i had a light grip on the bar.

at the time, i attributed it to user error.

Last edited by mtb_addict; 06-07-20 at 08:39 PM.
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Old 06-07-20, 08:22 PM
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It just dawned on me; maybe you should put the more predictable setup back on before you cause probable harm to someone else.....
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Old 06-07-20, 08:34 PM
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Originally Posted by mtb_addict
Regarding the steering bearing tighteness...
my steer bearing is perfectly adjusted...no freeplay...no drag.
but, i guess i can try to tighten the bearing a tad more...maybe a bit of drag will help.


one more thing, is that with the more forward stem, putting my body weight on the bar will make it feel less stable.
No, if its adjusted properly then don't tighten it further. I was concerned that an over tight headset was causing the problems. Actually. If you hold the front brake on and rock the bike back and forth can you feel any movement then?
Steerng from behind the centre point can be even wonkier than at the centre point yet I don't really believe that this is your problem. Is the front wheel aligned in the forks?

EDIT: and maybe the headset bearings are worn out. If it was me I would be pulling it apart and checking it before cleaning it and rebuilding it with fresh grease.
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Old 06-07-20, 08:43 PM
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Originally Posted by AnthonyG
If you hold the front brake on and rock the bike back and forth can you feel any movement then?
.
no movement. i spent alot of time adjusting the steering bearing, to get it right, when i first got the bike in January. But i didnt regrease it, cuz it felt smooth enough.


Originally Posted by AnthonyG
Is the front wheel aligned in the forks?
yes. perfect alignment. The rear triangle also align good.

One thing though....is that there is alot low speed wheel flop...and it is dominant to left side.

Last edited by mtb_addict; 06-07-20 at 08:52 PM.
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Old 06-07-20, 11:19 PM
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Originally Posted by mtb_addict
no movement. i spent alot of time adjusting the steering bearing, to get it right, when i first got the bike in January. But i didnt regrease it, cuz it felt smooth enough.




yes. perfect alignment. The rear triangle also align good.

One thing though....is that there is alot low speed wheel flop...and it is dominant to left side.

Well I'm guessing that that's it. Redo the front wheel bearings.
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Old 06-08-20, 03:39 AM
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Went back to scene of the crime. I hadden realized how big those bumps were. until i got closer to take these pics. ..Thats a 12 inch pump.




​​​​​​i landed near the first patch of grass.



it looks like the top poles were sawed off!


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Old 06-08-20, 03:46 AM
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On the way back to the scene of the crime, I noticed how hard and slippery the rubber grips are. When the path got unexpectedly bumpy, my right hand almost slipped off!

Last edited by mtb_addict; 06-08-20 at 06:07 AM.
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Old 06-08-20, 05:46 AM
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Yes, those images in Post #19 seem to confirm my earlier idea that if your front wheel hit the side of one of those bollard bases that the front wheel could very easily get deflected. You could be down before you even realized it. Those remaining bases are accidents waiting toi happen especially if the bases are wet from dew or rain.

Cheers
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Old 06-08-20, 06:12 AM
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Originally Posted by Miele Man
Yes, those images in Post #19 seem to confirm my earlier idea that if your front wheel hit the side of one of those bollard bases that the front wheel could very easily get deflected. You could be down before you even realized it. Those remaining bases are accidents waiting toi happen especially if the bases are wet from dew or rain.

Cheers
Strange thing is i ride here dozens of times before w/o any problem....until last week.

It was a confluence of multiple events at the same time: getting dark, destracted by lots of pedestrian, complacency bec i was almost home, fatique, slippery rubber grips.
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Old 06-08-20, 06:30 AM
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Originally Posted by mtb_addict
Strange thing is i ride here dozens of times before w/o any problem....until last week.

It was a confluence of multiple events at the same time: getting dark, destracted by lots of pedestrian, complacency bec i was almost home, fatique, slippery rubber grips.
Yes. That can do it. However, those bollard bases are a hazard pure and simple. I'd notify whomever is responsible for that path and tell them that the bollard bases are a hazard and should be removed. The next rider that hits them and crashes might not be so lucky as to escape more serious injury.

Cheers
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