What's this a picture of? - Bike Magic

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What’s this a picture of?

What’s this then?

That’s a macro blown-up cross-sectional picture of this, when it snapped!

I’ve had an Ameoba post on test for a few weeks. Yes, only
a few weeks. Most Amoeba stuff is great, infact there’s a whole lot of stuff out
there that the company that makes Amoeba (Jinn Yeh) make for other manufacturers.
Have a look at the head on the seatpost and go and spot how many other manufacturers
have a similar design on their posts.

I’ve always been suspect of carbon parts. Though it’s getting increasingly popular,
it’s never seemed tough enough to me for high-impact parts. I know Trek have made
huge advances in carbon fibre construction, and that there are many, many different
types of carbon fibre out there, and tarring all carbon fibre with the same brush
is tough… a bit like comparing a mild steel bike frame (like you get on catalogue
specials) with something made from 853. That’s not fair really. But when you’re sold
carbon, it just says carbon. And you should all be aware that there’s lots of different
carbon about.

Easton make a great deal of noise about their posts being much stronger in impact
than others. I hope they are. There are loads of people riding around on them. The
problem I percieve with carbon, particularly used in areas where it’s clamped in
place, like handlebars and seatposts, is that there’s an awful lot of stress concentrated
in one place. And carbon doesn’t like to perform too well when it’s got concentrated
stress on it.

I haven’t got a shot of the rider who was riding the post at the time it failed,
and thankfully it didn’t stick half way up his arse. But it did snap. And he did
have to ride 5miles without a post. He wasn’t too happy, but I was glad (in a way)
that it happened to him, rather than to me (as he was on my bike), half way in the
back of beyond with the dark setting in and no hope of getting home in one piece.

My engineering buddy (Hi Ade!) says

"It looks like the resin carbon bond
has gone, if this caused the original failure or was a result of the damage as it
broke? There was some evidence of a compressive failure on one side and a compressive
on the other, but there does seem to be a high resin content, which you would expect
in a wet lay-up, it was crap. I suggest they try a piece of broom handle as it may
be lighter and a lot stronger"

Carbon is a great material. Without it, we wouldn’t exist. I’m just not sure it’s
that suitable for seatposts.


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