Accident Following Seat Bolt Shearing

ajfish

Hi,
I am new to this forum but just wanted some advice on an accident that my girlfriend suffered this last weekend.
She was on her Scott Speedster which is two years old and just approaching a downhill section at about 25 mph her saddle loosened and she lost balance coming off the bike. She skated down the road like a block of cheddar on a cheese grater and it wasn't a pretty sight. She was in shock and pretty badly bruised, cut and grazed. We were waiting in A & E until 3am to get x-rays done which thankfully proved "okay". Fortunately she was wearing a helmet which cracked where she hit her head on the road. She got a friend to pick her and her bike up from where she had the accident. She was in shock for a good few hours. Fortunately it was on a quiet road. She was very lucky.
On examining the bike the cause of the accident became apparent. The two bolts holding the rails of the saddle to the seat post had sheared at the heads of the bolts. The bolts run through a threaded clamp arrangement which clamps the saddle rails to the top of the seat post. Once the bolts had sheared there was nothing holding the saddle to the saddle post.
Is this a common occurrence? The bike was prepared by a cycle shop and one would assume that the bolts were torqued to the correct setting, so could it be faulty bolts or even a design fault (if this type of thing proves common).
I'd be interested to know other's experience of this.
Thanks

cougie

Two bolts holding the saddle on had both sheared ? I've never heard of that before. If one had broken earlier - maybe it hadnt been spotted and the accident happened when the other one broke ?

I've been riding 30 years and I dont think I've heard of an accident like this. I've broken a saddle rail, broken a seat post but not the bolts holding the saddle on.

diy

Due to the age of the bike, its for you to prove that it was a failure on the part of the cycle shop. Its possible that the bolts were over tight and this caused them to fail. They actually don't need to be that tight. It could also be due to sitting badly on the seat or having it poorly adjusted or simply fatigue. For you to have any chance of a claim you'd have to show the basic elements of negligence. Google Caparo Test.

Unless they 'fess up to incorrectly adjusting something or you find a known fault with the model of seat clamp, I think it will be almost impossible to show that something they did caused the failure and that the failure was reasonably foreseeable and that injury would be likely.

A better option is to get some of the special wound dressings that are supposed to heal skin quickly.

slowbike

diy wrote:

Due to the age of the bike, its for you to prove that it was a failure on the part of the cycle shop. Its possible that the bolts were over tight and this caused them to fail. They actually don't need to be that tight. It could also be due to sitting badly on the seat or having it poorly adjusted or simply fatigue. For you to have any chance of a claim you'd have to show the basic elements of negligence. Google Caparo Test.

To sheer the boltheads off SS bolts that size (M5/6 I think) you'd have to go some - and not possible with normal tools - and you'd strip the thread before you sheered the body of the bolt.

ajfish

I wasn't really after compensation (although I guess it would have been nice to have some flowers for the poor girl - but that's my job), I was just interested to know if this is a common occurrence with seat post generally, with Scott seat posts or seat bolts? Clearly, if the bolts were torqued to the correct setting (and I feel confident that they cycle shop did this correctly) then if bolt failure is likely owing to impact (pot hole etc.), then is there a recommendation to change the bolts periodically? Should i be thinking of fitting some 316 stainless bolts in the future!?

ajfish

cougie wrote:

Two bolts holding the saddle on had both sheared ? I've never heard of that before. If one had broken earlier - maybe it hadnt been spotted and the accident happened when the other one broke ?

I've been riding 30 years and I dont think I've heard of an accident like this. I've broken a saddle rail, broken a seat post but not the bolts holding the saddle on.

Well, as the girlfriend says "that's a relief to know then". ;-) Seriously though, I looked at the bolt shanks which were left and both appeared to be clean breaks. Neither was more tarnished than the other. She said that the saddle felt funny just as she was approaching the hill so maybe one did go fractionally before the other.

goonz

Have you any pics of the seat and bolts?

barrybridges

Sounds pretty terrible and I hope your other half is OK.

I get what others are saying, but seat rails bolts really don't just snap or shear like that. You'd have to put a hell of a lot of force on them to get them both to give way at the same time. I would be surprised if one had gone before the other, as you'd presumably feel it or hear it - the seat would be a little loose.

With that in mind, I wouldn't automatically say that it's up to you to prove fault, because it's a pretty catastrophic failure to have occurred and would be very very difficult for you to engineer yourself! And in any event, I presume the SAD FART rules would apply here (particularly the RT bit).

I would suggest taking it back to the bike shop and asking them to raise it with the manufacturer to see what they say, but take photos as evidence.

I expect the best you can get out of this is some kind of goodwill gesture.

ajfish

barrybridges wrote:

I presume the SAD FART rules would apply here (particularly the RT bit).

Sorry Barry, you will have to explain that one to me please.

ajfish

goonz wrote:

Have you any pics of the seat and bolts?

I will post some pics when I get a moment.
Thanks

IanLD

http://www.moneysavingexpert.com/shoppi ... s-exchange

Just looked it up myself

Sounds a nasty accident and hope she is recovering well.

ajfish

Thanks Ian, she is having the dressings changed for the second time tomorrow so a few watery eyes no doubt, ouch.
I did actually look at the link at moneysavingexpert and it did get me thinking that if the bolts were at fault, and let's face it, what else could it be, then the fault, such as it, is must have been there from day 1.
I will get some pictures posted tomorrow after I have charged the camera battery.
Thanks

wongataa

I've had the seat clamp bolt shear on me once. The bike in question only had one bolt clamping the seat to the stem though. Thankfully I managed to stay upright and stop safely when it happened wondering why my seat had suddenly moved and hit me in the nuts. The I had a look and saw the sheared bolt and missing clamp.

Jim C

The design of some seatpin clamps means that the bolts are under varying tension and compression. They fail thru fatigue. Its not uncommon. Some designs ( I remember a u.s.e. post failure where the bolts were m4- very poor design, all in the name of light weight). M5 or M6 stainless bolts are not particularly strong- better grades of bolt and swapping them every couple of years would help prevent this

jockywilson

Had the same happen to me a couple of years ago with a single bolt design seatpost when riding my fixed gear bike. Was fortunate that it happened just after pulling away from a set of traffic lights, so the lorry that was immediately behind me managed to stop in time. A very strange experience when you're suddenly on the deck without any warning. Had a few scrapes and a large cut on my elbow, but could have been a lot worse.

I did have a brooks saddle and heavily loaded carradice saddlebag attached (which had a tendency to swing about) which may have contributed to extra stress on the seatpost bolt, but that's conjecture on my part, with absolutely no scientific evidence to back it up!

Does seem strange that both bolts sheared on your girlfriends seatpost sheared though....

barrybridges

ajfish wrote:

barrybridges wrote:

I presume the SAD FART rules would apply here (particularly the RT bit).

Sorry Barry, you will have to explain that one to me please.

Products must be:

Suitable (for their intended use)
As
Described (and last)
For
A
Reasonable Length of
Time

ajfish

What would be a reasonable length of time for seat bolts? More than two years I would guess? Presumably, if they failed to hold the seat to the bike then they can hardly be fit for purpose? However, if the bolts were faulty, then I guess there is no way that the shop or Scott would have known this? No-one would have known so isn't it just one of those things?
I have taken the pics but forgotten my camera. Will post tonight.

keef66

Just because they didn't know about it doesn't mean they have no responsibility for it.

junglist_matty

...

junglist_matty

firstly....... OUCH, MAHOOOSIVE OUCH!

secondly..... It's your job to check the bike is in good condition before you ride it, the manufacturer/shop can't be held responsible for a bolt snapping, a frame/forks yes, but not a bolt. It can't be proven that it's the same bolt that was bought with the bike, you simply won't get anywhere for an accident caused due to a faulty bolt.

Finally.... I have snapped a saddle bolt before (a friend of mine has also done the same), but that was on my mountain bike and it was because of my own fault, being lazy (actually, I was totally knackered) sitting on the saddle whilst going down a bumpy DH section not at very fast speed, a fairly hefty bump and the saddle just came straight off!

I'd think to break one on a road bike you'd need to hit a huge pot hole or something and even then, the wheel would be totally destroyed before the saddle, must have been massively bad luck to be honest.

markos1963

Without calling you a lier but is there the possibility that the crash might have been caused by some other factor and the shearing of the bolts could have been caused during the crash?
I have a single bolt design on my TT bike, ride on the nose of the saddle and have hit some pretty big pot holes during races but have never even loosened it so I would doubt two bolts going at the same time.

ajfish

I have to say I hate this litigation culture that seems to be sweeping the country, but I do think it's important that if there is an inherent fault in either the design or type of bolts used, then this needs to be highlighted for the sake of others. She was very lucky that no cars were around when she fell and that she wasn't going faster. She didn't break anything, but someone else could be seriously injured.
Just before the downhill section she said that she felt the saddle go funny, I think that's perhaps when the first bolt went putting strain on the second which subsequently failed when in the downhill section. There was no way she was riding on one bolt for any length of time. The faling of the bolts definitely caused the saddle to come free from the seat post and for her to fall off.
Unless there is any recommendation to change seat bolts after a period of time then you presumably have to be comfortable with the assumption that the bolts will last the life of the bike?

barrybridges

Lots of interesting replies, but at the end of the day the pragmatic solution is to call the shop you bought it from and then (either yourself or through them) the manufacturer.

Heaven knows, they might actually try to help you and will be on your side...

robz400

Hope she's ok! I crashed at 20mph and lost a suprising amount of skin!!

Broken seat eh? I saw a video in Youtube of someone breaking an office chair just by sitting down.... they did appear to weigh round 25 stone though.... just saying like :twisted:

ajfish

Here, hopefully, are some pictures.
Picture 1 showing where the bolt heads were.
http://www.WatchBattery.co.uk/images/Shear1.jpg

And Picture 2 showing how it should fit together. In this picture the bolts would do up from the bottom, what you are seeing at the top is the end of each bolt.
http://www.WatchBattery.co.uk/images/Seat_post.jpg

ugo.santalucia

Given the accident happened after two years, it is quite easy for any shop to claim that it is lack of maintenance or incorrect use. These things happen... components don't last forever and some don't last very much at all. If you wanted to take the case to court, you need to show the bolt sheared due to being badly installed and not for metal fatigue (which is likely to be the cause) or incorrect use. If you had the bolt, this could be assessed.
Given the damage is limited and the compensation will be small, it sounds like a huge effort which might even go nowhere.

ajfish

I agree. I think we both wanted to make others aware that this could happen and were interested to know if anyone else had experienced this. Girlfriend is quite philosophical about it, realises just how lucky she was and has said "it's probably due to my fat arse" which is quite funny, because she doesn't actually have a fat arse (he says knowing she's probably reading this!)
I think metal fatigue is a likely cause due to constant moving on the saddle. I guess fitting stainless steel bolts would be better than standard steel ones?
Thanks to all the contributors.

racingcondor

I've known it to happen once (guys saddle went spinning across the road during a crit) but it's not common (I suspect broken rails are a lot more common).

Glad to hear she's alright.

keef66

I guess fitting stainless steel bolts would be better than standard steel ones?

I doubt it. Doesn't look like corrosion was an issue from your photos.

ajfish

I just thought that they are stronger regardless of the fact that they are also resistant to corrosion.

jgsi

ajfish wrote:

I just thought that they are stronger regardless of the fact that they are also resistant to corrosion.

Was the saddle fixed in the middle of the rails or at front or back?
Saddle on the extremity and clamp bolts working loose on bad roads and potholes just might have caused the failure.
Just a thought.
Whats your remedy... new seatpost with an alternative clamp design... I would trust Ritchey finishing kit to be up to the job of keeping a saddle on!