Friday, April 24, 2009

Thomson Failure article from Cozy Beehive

This excellent post comes from the Cozy Beehive, one of the cycling blogs listed in the links to the right here on my own blog. The first reported failure of this Thomson Seat Post from Beehive got me very interested in the hows and whys, and I must say, that with 4 Thomson Elite posts, and 2 Thomson Stems in my quiver with not a whit of trouble from anything, my initial reaction to hearing of the failure was 'operator error'. I'm not writing it off as that, but just saying...


The Cozy Beehive link

Broken Thomson Seatposts & The Overtightening Syndrome

and the thread on MTBR


Picture is from the MTBR thread...posted by 'Apacherider'
When I worked in the bike business way back when, we joked about the "JRA" failures. That is, when a customer comes in to the shop with a bike or frame that he or she has clearly abused to the point of failure, and then explains culpability for the failure away from themselves by claiming that they were "Just Riding Along". Just by looking at the part, or bike, or what have you, a huge percentage of these failures were pretty obvious in how they developed, although I've never calculated statistics for the hows and whys. As shop staff, we would cut the customer a deal that typically meant eating the profit for the sale in the first place...customer is always right, even with a wacky JRA story as their only excuse.
I hated the JRA cyclists. I never understood not wanting to take responsibility for breaking something. Hey, most of the time, if the guy would have just owned up to it, the shop would probably come to your aid in the first place, without your having to resort to some wacky tale. I don't know enough about the circumstances of this failure, but my experience with the product in question, and my belief that something big had to happen to this post to set the stage for the break...crash, roof rack garage interference issue, rider weight and/or style, makes me wonder...was he really just riding along?
I knew a guy in college that had a Diamond Back Apex mountain bike, a pretty nice True Temper OX steel tubed rigid bike with full Deore DX parts and a nice smattering of ancillary parts. Well, he had the bike for about a month when one night he was riding across campus in the dark, and cut through what he thought was a field, but which was in reality a temporary parking lot frames in big pressure treated pine logs, much like telephone poles lying prone on the ground. He rode headlong into one of those logs and obviously, wrecked the bike. The fork pushed back and buckled the down tube of the frame. He actually had the audacity to take the bike back to the Diamond Back dealer and request a warranty replacement. I'm sorry, but that's not Diamond Back's fault, and you were not Just Riding Along. Sad wasn't a super fancy bike, but it deserved better...


Conversely, I do not hide my disdain for companies that I feel make crappy parts. Kooka, for example. Kooka introduced some CNC machined aluminum cranks at Interbike in 1993. They were beautiful. They were also fragile flexy crap. Kooka changed their cranks design and chosen materials and manufacturing process many times, and yet I've seen multiple examples of broken Kooka cranks regardless of their manufacture date. Kooka just made crap, and they're out of business today because of it. (Actually, I think the brand still markets bike junk made overseas, but only after the originators of the Kooka name left it unprotected as a trademark after going belly up.)


There are two choices with this seat post, either A - the Thomson Elite Post has some inherent design issue or materials shortcoming that resulted in this failure, or B - like the Diamond Back Apex frame that bit the dust after being ridden headlong into a felled tree, this post failed because of operator error, either by being hurled off a cliff or clipped off the roof of a car by a Burger King Drive Thru or some other such catastrophe.

I'm inclined toward B.


Ron George said...

I was inclined towards B as well but the person I talked to came out as a decent honest fellow...Thanks for the link. I did not hear about Kooka cranks but the name itself puts me off (sounds like kaka, a baby's way of saying "Shit"). Tell me more about them. What made them fail? Material issues or customer service? I could add them to my "Bad Designs" list on the left sidebar of my blog. Have you looked there?

utahDOG! said...

Kooka cranks came out in the early 90s when all you needed was that CNC look and fancy colors. The original cranks were cut from raw bar stock, and came in 385 and 405 gram weight options. The 385s were so flexy that I could make them twist by about 15 degrees by bobbing on the pedals. I sent them back, and went with the 405s, which snapped after about 4 months...non drive side at the spindle. Two of the other three sets that my shop got in also failed about the same time, all 405 gram 'downhill' models also. The 4th pair was sent back as a precaution. The original Kooka arms were exactly the same side to side, with just a spider pressed and center screwed on the drive side, so the non drive side lacked the reinforcement of having the spider pressed around the spindle hole like a colar...that was the weak spot for those. Kooka shifted to a heavier non drive arm design with more material on the backside of the arm...didn't help, I saw 2 pairs of those break. Then the forged models came out, ala Race Face. They were not Race Face at all. The forged arms had the strange tendency to 'peel' apart, like a wood shaft splitting along the grain. I'm not sure the 'forging' process there that would cause that to happen, but it didn't work either way.

3 redesigns of their arms in about as many years, and a President of the company with the last name of 'Fail' (Stan Fail! HA!) Kooka was a joke from the start and never got any better. Garbage.

Kooka as a name was supposed to be some Australian tie-in somehow...and the Kookaburra bird was the company logo.

Stan Fail! Ha!

Ron George said...


Interesting. This certainly will be inducted into my "Bad Designs" list on my homepage. It already has. Check it out. Just search for "bad design" (ctrl+F).

Anonymous said...

I had a 1989 or 1990 Diamondback Apex beautiful yellow, the predecessor paint job to this black one, that bent right behind the steering tube after I rode down a set of 16 stairs on it.

That bike should've been able to take that. I wasn't doing 6' power drops on it, something it still should've been able to handle.

But bikes are much stronger now.

What about those titanium cranks that all broke, remember those?

Beautiful. Superlight, and SNAP