Advice Welcome. Riding Accident. Bike Destroyed

Bicycle related chatter & discussion
silly_billy_boy
Posts: 39
Joined: 20 Sep 2011, 14:11

Postby silly_billy_boy » 06 Nov 2011, 13:39

Hi,

I am Bill, a new member and been on a few of the weekend rides now but unfortunatley has come to abrupt stop/pause so havent been there this weekend.

Had a weird head-on accident with another cyclist on the Bay Run on my ride home from work on tuesday and ended up destroying my bike.

photos of the damage are here (can never work out how to embed photos into forums)

http://www.flickr.com/photos/billchant/ ... 938264727/

so,
- I only had tiny graze on chin which i practically gone, other rider had tiny grazes but a damaged helmet from hitting the concrete and just a buckled front wheel and bent lever.

- It happened on a blind corner and was so sudden there was no time to react. Neither of us really remember anything of it. Both of us thought we were keeping left. It being a blind corner I roll through it carefully and she was also a careful rider. So was not anything major, obvious from no average/major injuries.

- My front wheel still looks true (only a dent which looks was from where the pedal (and assume my foot) went into it on the way through. No fork damage, no other marks on the bike. However the frame has a neat rip along the weld at the BB (most of frame is aluminium) with dull, brittle fracture surface. being an engineer this looks like a dodgy weld which is quite possibly why the frame failed so spectacularly. I have ridden for as long as I can remember and have had some big stacks. This was nothing compared to many i have had and this is the first time I have ever seen a frame fold like that. (is even all still in alignment)

So my questions are.

- Does the insurance that you get as a member help towards bike damage?

- I have already approached the shop I bought it from about a replacement frame and for the importer/manufacturere consider the weld issue. So far there is an offer of a new frame but at a pretty much retail price. Should I now deal with the importer directly? Is it worth it?

- Finally, any recommendations for replacements? I really cant afford anything, but as this was my practically un-ridden pride and joy that was a big investment ad was enjoying finally having it out this spring (after being sat away for a couple of years due to illness/rehab stuff) Was up to 200km of riding joy a week on it already. I kinda want to try and get something else just as nice.

so any advice, ideas welcome.

cool bananas
Bill who has had a bad bike year (this tops off a few motorbike disasters)

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 06 Nov 2011, 16:34

1) Membership insurance is to cover 3rd party damages and medical/income protection for the insured. No personal equipment cover.
2) That kind of frame buckle (top and down tubes) is common with significant frontal impact and I would say the downtube/BB weld fracture is secondary. In any case, frame warranties only cover failure under normal usage, not accident induced damages and misuse. If you get lucky with the BMC distributor, then it's a Lotto win.
3) Seek secondhand frames on eBay and other online places. I assume the rest of the fit kit (bar/stem/groupset/wheels) is in good shape and can be easily transferred to a new frame.

Glad to hear you, the rider, are not more seriously injured. Good luck with your search for a replacement!

User avatar
marc2131
Posts: 1120
Joined: 03 Jul 2011, 13:14
Location: Ashbury
Contact:

Postby marc2131 » 06 Nov 2011, 17:11

Bill
Sorry to hear of your accident. Good to hear both riders weren't hurt but what horrible damage to a beautiful bike. :cry:
If this accident happened despite the fact both parties were riding responsibly, I believe the relevant councils should be notified of this - it is their responsibility to keep the bike route safe.
Where exactly along the Bay Run did you have this accident?
The Bay Run emcompasses parts of Leichhardt, Ashfield and Canada Bay Councils.
I can directly help you with Ashfield if it took place there.
Regards
marc

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 06 Nov 2011, 17:23

I'm also interested in knowing the exact location of the accident. I can only think of two possible locations. The squeezed 90 degree corner at Dobroyd Pde and Timbrell Drive, but doubt any one would carry much speed at that point. Or there's the one on the shared path, east side of Leichhardt rowing club.

User avatar
Simon Llewellyn
Posts: 1532
Joined: 13 Nov 2006, 22:31
Location: Tempe Velodrome

Postby Simon Llewellyn » 06 Nov 2011, 17:44

Wow that's a spectacular break! Doesn't say much for BMC. What size frame are you looking for?

timyone
Posts: 4380
Joined: 22 Nov 2006, 20:29

Postby timyone » 06 Nov 2011, 19:18

that is the second BMC I have seen in two bits like that, the first was a track frame! (the pics are probably in the awesome track pics thread in the track section?). I still wouldn't start saying it is just BMC, as I have seen other brands do similar hey.

Is your frame carbon? It isnt one of the composites is it? I guess that when you add the speed of both of you together that is a bit of an impact! cracks in the bottom bracket used to be heaps common in carbon bikes in general though!

I ride a BMC, and have dropped it, but nothing that interesting to test it like that hey!

silly_billy_boy
Posts: 39
Joined: 20 Sep 2011, 14:11

Postby silly_billy_boy » 06 Nov 2011, 19:31

hi,

thanks for the responses.

- thanks about the insurance anser. Looks like I will be out of a bike for a while now, as there is no chance to know who was actually in the wrong, or if we were both near the centre and clipped. There is no point aguing with the other rider?

- i am questioning the frame breakage as it wasn't a big impact, both of us not injured and is a slow part of the track. If it was anything half significant i wouldn't be questioning it. Seems like I am stuck though. sure won't be having another BMC. A few engineers have seen the photos and straight away think the weld is suspect.

- the location was at the Leichhardt Rowers at the end of glover street. I was coming from the east and turning into the left corner under the trees. I was only thinking a few days before that I should stop riding on the track due to near misses, mainly with unattentive joggers running randomly across the riding track. Should have gone with that gut feeling. I am alos defientely at the careful end of the spectrum when it comes to how I ride around there.

- It was a 56cm frame (I am 6'2"). Looking at what is out there at the moment but not much appeals.

Thanks again for the responses.

cool bananas
bill

silly_billy_boy
Posts: 39
Joined: 20 Sep 2011, 14:11

Postby silly_billy_boy » 06 Nov 2011, 19:33

hi, the frame is aluminium with carbon seat stays and forks. No damage at all to the carbon bits, actually not a scratch on the bike at all. :(

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 06 Nov 2011, 20:19

If the only failure point was at the weld point, then there'd be an arguable case. As there's associated buckling of both top and down tubes, it's hard to excuse the magnitude of impact. And as we know, it's not so much the "biggness" of the impact, but the specific magnitude of the force vector. I wouldn't fault BMC though as they are a highly reputable bike maker with quality products. I would like to think it's the perpetual weight shavings on these modern alloy frames to be the more relevant issue here. Still, wait and see what the distributor has to say.

Very sorry to hear that you are not seeing anything that catches your eyes at the moment. Keep looking as opportunity buys do come and go. 56cm is a pretty common size.

silly_billy_boy
Posts: 39
Joined: 20 Sep 2011, 14:11

Postby silly_billy_boy » 06 Nov 2011, 21:16

If the only failure point was at the weld point, then there'd be an arguable case. As there's associated buckling of both top and down tubes, it's hard to excuse the magnitude of impact. And as we know, it's not so much the "biggness" of the impact, but the specific magnitude of the force vector. I wouldn't fault BMC though as they are a highly reputable bike maker with quality products. I would like to think it's the perpetual weight shavings on these modern alloy frames to be the more relevant issue here. Still, wait and see what the distributor has to say.
i can see your point, thing is that it looks like the BB weld went first and led to the collapse of the other tubes once strength/stiffness is gone. don't think it likely to have happened the other way around. From working as an engineer the brittle fracture (obvious from the nature of the fracture surface) is fast and would have happened first and the slower buckle/bend second.

so it seems reasonable to think there is an issue with the frame.

if it is an across the board problem with weight saving then for a collapse like that to occur in a non descript accident then safety of bikes is a real concern.

Distributor has only offered replacement fram at a price in the retail price range at the moment :(

cool bananas
Bill

shrubb face
Posts: 1010
Joined: 09 Sep 2008, 01:43
Location: Marrickville

Postby shrubb face » 06 Nov 2011, 22:33

Sorry to hear about your crash. As i discovered myself a fortnight ago, bike paths are dangerous places.

Not that it really matters but i think you probably have the failure order the wrong way around. When you impacted the force would have been roughtly perpendicular to the forks, which would have induced a positive bending moment in both the top and down tubes, causing the sections to buckle. Once the downtube yielded and started rotating about this bottom bracket the bottom of the tube was put in tension which cause the weld to fail. The majority of the stiffness (resistance to bending) in this axis is coming for the section factor of the tube rather than the end fixing, in this scenario.

And because I was bored and meant to be doing other work.
Image

silly_billy_boy
Posts: 39
Joined: 20 Sep 2011, 14:11

Postby silly_billy_boy » 07 Nov 2011, 20:33

hehe, trusty old fea. am myself a nafems registered analyst, worked at strand7 then yrs of consulting after that.
good to see a good use for it :)

pondering the model itself and not sure how you have/where you restrained it from spinning. not sure if having the forks as a full momentconnection beam is ok due to the bearing arrangement .. i wish i had time to do it as well :)

anyway .. as well as the bending moments there will be axial loads in the members that will significantly influence the buckling. I would think the downtube is in compression and top tube in tension as it is kinda 'rotating' about the bottom of the headset.

so the tension in the top tube would counteract the buckling influence of the moment and the compression in the downtube would add to it. So the most likely to buckle is whatever is in compression (maybe the top tube is? or is model saying downtube?) .. so then which ever is in compression i would imagine would go first and if it is the downtube both ends will have same compression but less bending by the looks at the bb. if this is case and bb weld is weak then stiffness here goes if it fails (but if weld not weak maybe it went first at top end .. or both ends simultaneously). so then downtube cant hold load, puts top tube into compression and buckles it then top of downtube would follow with the bending up there.

thats a theory anyway ...

would like to know what you think .. happy to be wrong :)

experience of stacks, including one that broke a fork but not frame comes into it as well .. and just that gut feeling something wasn't right on this frame.

cool bananas
bill, now in nerdy engineery thought :)

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 07 Nov 2011, 20:59

was the FEA model based on hollowed tubular members? Or were they solid rods?

silly_billy_boy
Posts: 39
Joined: 20 Sep 2011, 14:11

Postby silly_billy_boy » 07 Nov 2011, 22:04

rods or tubes, it wont matter as the bending moments and loads wont change. the cross section only matters when looking at the stress and if there is significant differences in cross section of the members.

all the tubes are slightly optimised in shape on the real bike... might be jumping to conclusions but it is likely to help with optimising stresses in each tube more than changing the stiffness of each one significantly 9they are all similar sizes) but for this simple analysis it probably has little effect on what is trying to be looked at.

i hope that makes sense.

cool bananas
bill

User avatar
mikesbytes
Posts: 6991
Joined: 13 Nov 2006, 13:48
Location: Tempe
Contact:

Postby mikesbytes » 08 Nov 2011, 08:10

The damage is consistent with hitting an object head on and is no reflection the brand of frame.

I'm guessing that the collapsing of the frame may have assisted in reducing Billy's injury risk, slowing him a little before he hit the deck

User avatar
Toff
Posts: 1215
Joined: 20 Sep 2007, 14:34
Location: Stanmore

Postby Toff » 08 Nov 2011, 09:36

Hmmm.

3 things:

1) A steel frame would be rideable after an impact like that, although possibly some fork trail adjustment. I recommend steel. :mrgreen:

2) There is plenty of data that shows that bike paths are more dangerous than roads. Collisions and falls are much more common, and broken bones especially are significantly higher on bike paths. My most recent fall was on a bike path. I recommend road riding at all times.

3) Some home contents policies cover personal items outside of the home. These usually include wallets and sunglasses, etc. but several policies include bikes too. Go through all your insurance policies and check. You might be lucky.

timyone
Posts: 4380
Joined: 22 Nov 2006, 20:29

Postby timyone » 08 Nov 2011, 11:18

I bent my steel frame after similar impact, stationary car on a round about, not going that fast, bent the top tube etc, I only noticed when the bits began to rust. Bikes aren't great for head on's

User avatar
Toff
Posts: 1215
Joined: 20 Sep 2007, 14:34
Location: Stanmore

Postby Toff » 08 Nov 2011, 12:36

But you rode home didn't you Tim?

silly_billy_boy
Posts: 39
Joined: 20 Sep 2011, 14:11

Postby silly_billy_boy » 08 Nov 2011, 19:03

hehe :-)

once mountain biking on steel bike with steel rigid fork ..

landed a small jump with front wheel in crossways rut, fast, over the bars, 360 pirowet on my head with feet still locked in pedals .. cracked helmet ..

bike damage was jsut forks bent back a bit .. still rode it rest of DH and home (handled a tad funny, hehe) .. then to shop to get new forks :-)

yep .. i am keen for steel again now ;)

timyone
Posts: 4380
Joined: 22 Nov 2006, 20:29

Postby timyone » 09 Nov 2011, 07:42

Yeah I didn't realize till a few months later

User avatar
geoffs
Posts: 239
Joined: 20 Nov 2006, 12:07
Location: Ashbury

Postby geoffs » 09 Nov 2011, 13:18

Sorry to hear about your collision.
You should be able to swap all the parts onto a new frame.
I was talking to a company that imports bike and frames from Taiwan importer in Melbourne last week and he offered me unpainted 58cm good quality aluminium frames for $250. I think a fork was included but I'm not sure.
Have a look on ebay or bike exchange
I have done the same amount of damage to a steel bike, however the collision involved t-boning a car that pulled out in front of me when I was doing about 30kmh.
We had another broken carbon frame in the shop this week. broken seat stay caused by bike falling over against the gutter.


Return to “Conversation”

Who is online

Users browsing this forum: No registered users and 21 guests