Author Topic: Saddle bolt fail  (Read 1986 times)

in4

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Saddle bolt fail
« on: February 14, 2016, 05:44:42 PM »
Thought I'd share this one with everyone as a cautionary tale.
I was out for a short spin this afternoon when I heard a 'ping' from behind. I was able to stop OK being on the flat and only doing around 12mph. I was surprised to see my lovely Brooks Conquest lying in the road. I parked up, collected the saddle and found all the bits. It appears that the saddle bolt failed. I guess I must have overtightened it when I adjusted it, but I've done 40+ miles since then with no hint of trouble. I'm quite careful about overtightening nuts, bolts etc. as a rule
(Engineer Father legacy) but I guess I must hold my hand up to this one. I've never heard of a saddle bolt sheering off before but am wondering whether I should carry a spare just in case. My Brooks is now not quite so pretty but I'll get the Proofide out and give it some love. I'll have a rummage around to see if there are any optimum tork recommendations around. Suffice to say it was a nine mile walk home ( which was rather nice in reality) and my Strava numbers are right out of the window now. Check your bolt people! Couple of photos FYI attached.

Danneaux

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Re: Saddle bolt fail
« Reply #1 on: February 14, 2016, 06:49:52 PM »
Ouch!  :P

So sorry for your misfortune and the damaged finish to your saddle, Ian. What a pity.  :'(

Glad you weren't hurt.

The bolt broke near where the threads meet the solid shaft. The last few turns of the die can sometimes create stress raisers and that is where they seem to go in my experience. Yes, overtightening could well have been a factor. I lube the clamp interface as well as the bolt threads, then reduce torque by about 10% compared to dry recommendations.

I don't seem to break saddle/seatpost bolts, instead I fracture saddle rails, causing me to gain some experience in transferring my saddle leathers to new railsets -- 3 on my own bikes so far, several others for friends. Brooks' chromed rails were sometimes hydrogen-embrittled during the chroming process; the black powdercoated replacements seem to be holding up well for me so far...along with using long layback seatposts so the clamps are in the middle of the rails instead of cantilevered from the forward end.

That said, I always take spare seat-binder bolts and spare bolts for the saddle-rail clamp. I can't afford a failure in the middle of nowhere, so a spare bolt or two added to the kit is reassuring and don't weigh much. I take extra bolts for my SPD cleats, too. They can be stored in the Nomad's rim-dynamo bracket on the fork.

Sorry for your misfortune, but grateful for your kindness in relating this cautionary tale.

All the best,

Dan.

in4

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Re: Saddle bolt fail
« Reply #2 on: February 14, 2016, 07:40:23 PM »
Thanks Dan. Main thing is that I'm uninjured. It could have been a very different outcome. Everything other than me is replaceable or repairable. From now on I shall carry a spare and give serious thought to carrying other spare bolts etc. I don't want to get caught out whilst riding through the boondocks.

rualexander

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Re: Saddle bolt fail
« Reply #3 on: February 14, 2016, 09:16:20 PM »
Bloke I cycled with in New Zealand once had a saddle bolt break like that.
He fixed up a temporary solution by cutting a section of fence wire from the nearest fence and binding the saddle clamp up with that tight enough to ride tentatively for twenty miles or so until we reached a mechanics garage who had a bolt that fitted well enough to make a better fix.

in4

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Re: Saddle bolt fail
« Reply #4 on: February 14, 2016, 09:51:19 PM »
My failed bolt has the letter J stamped in the head. Anyone know what that refers to?

mickeg

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Re: Saddle bolt fail
« Reply #5 on: February 14, 2016, 11:05:17 PM »
You are fortunate you are not injured.  And fortunate you found all the parts.

A gal I used to work with told me that one of her saddle rails failed this past summer while riding to work.  I asked if she was badly hurt thinking that she probably got stabbed by the seatpost.  But she said no, did not land on the seatpost, instead she crashed.  Called her husband who came to take her home.  I think she skipped work that day.

lewis noble

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Re: Saddle bolt fail
« Reply #6 on: February 16, 2016, 11:53:09 AM »
So, Dan, if you lubricate a thread (I normally put copper slick on pretty well all threads) you should not tighten it up as much as usual?? I seem to recall an article on here some time ago about thread tensions . . . .

My experience is that lubricated threads stay done up better and more reliably - I guess because the lubrication helps the threads seat better . . . .

I have probably started something now . . . .

Lewis
 

Danneaux

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Re: Saddle bolt fail
« Reply #7 on: February 18, 2016, 09:21:15 PM »
Quote
I have probably started something now . . .
Yep.  :D

If you grease your mounting bolts or use a liquid threadlocker, then it is standard practice to follow (lower) wet-torque values and not (higher) dry ones. For one among many references on this, see: http://www.intermotive.net/Tech%20Tip/Tech%20Tip%20-%20Jan%2008.pdf My Glover "Pocket Ref" sees a lot of use when torquing bolts both dry and wet. Plating makes a difference also. See: http://raskcycle.com/techtip/webdoc14.html

If you have a few moments to while away, Google "dry vs wet torque" and you'll see the issue is far from cut-and-dried! All acknowledge there is a difference, disagree on how much, and agree that manufacturers and companies often fail to specify wet or dry in their torque recommendations.

In general, see:
http://tinyurl.com/l8au99p
...or...
https://www.google.com/search?q=dry+vs+wet+torque&oq=dry+vs+wet+torque&aqs=chrome.0.57j59.1953016j0&sourceid=chrome&ie=UTF-8

For a more specific search, do "Dry vs wet torque +bicycle", as here:
http://tinyurl.com/mmblw5v
...or...
https://www.google.com/search?q=Dry+vs+wet+torque+%2Bbicycle&oq=Dry+vs+wet+torque+%2Bbicycle&aqs=chrome.0.57j62l2.2809j0&sourceid=chrome&ie=UTF-8

All the best,

Dan. (...who gets all wound-up about such things)

lewis noble

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Re: Saddle bolt fail
« Reply #8 on: February 19, 2016, 12:48:34 AM »
I knew it . . . !!

But thanks.
 

in4

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Re: Saddle bolt fail
« Reply #9 on: February 19, 2016, 12:02:24 PM »
I came across this interesting tool whilst having a clearout. I'm sure someone (  ;) ) knows what it is and what it is for!

onrbikes

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Re: Saddle bolt fail
« Reply #10 on: March 16, 2016, 01:48:25 PM »
Hey IN4

What an odd place to post this, butů..

I to have the same.
An old toolmaker friend gave me it in a pile and its a Starret.
It has 3 flats on the pointy end and a bunch of markings.

I think it may have been used to measure feet per minute. It may have been mounted in a 3 jaw chuck and turned on while holding onto it.

Am presently on tour and can have another look at mine and do a search with the model numbers.
Any antique tool shop will tell you.

in4

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Re: Saddle bolt fail
« Reply #11 on: March 16, 2016, 04:00:06 PM »
Well done that man and correct you are!

There is a video on youtube demonstrating its use; think it was chuck speed on a lathe that may have been subject to a variable electrical current. I think it was referred to as a tachometer too; different to how the word is used today.

https://www.youtube.com/watch?v=4RLnwgp6YcM

Thanks for posting though and do enjoy your tour; entirely free of any kind of tachometer.
« Last Edit: March 16, 2016, 04:54:51 PM by in4 »