Friday, December 5, 2008

Crazing Saddles

First, let me explain crazing. When you flex plastic enough, the surface in tension first develops microcracks (which look like little white-ish lines) before failing. This process is called crazing. If you stress the plastic enough times, the cracks will propogate (spread) and coalesce (join up) and create a fracture. This is what happened when my dense derrière remounted my cyclocross saddle over a series of probably 10 races. Result - cracked straight through:

The fracture finally competed it's journey through the shell of my saddle during a race in Livermore, California this year. On the first remount of the first lap, I heard a loud crack which I thought was my seat post slipping. I kept racing (since all the important parts were still attached to the bike) and eventually realized that I was sitting on the ass-hammock you see in the picture above. It probably dropped my saddle-pedal height about 2cm. The pounding of my heart in my ears pretty much drowned out all other sounds so I had plenty of inner thought time to consider how I was going to get a saddle and fix it before the next day's race. I have now broken three saddles racing cyclocross. Two shell failures and one rail failure (via bending). Anyone got any ideas? My remounts are pretty smooth, not too much high flying.


-d said...

I haven't really looked into those I-beam saddles, but I assume they have structural support where you need it... you'd probably need a new seatpost, though.

-p said...

Not only would I need a new fancy pants seat post, but those things probably have no flex in the middle, making for a harsh, taint-jacking ride.

-d said...

True. Just throw a Brooks on there - probably not the cyclocross saddle of choice, but I bet it would break in nicely with all your remounts.