Friday, August 18, 2006

bike broke

Well, this is the first time I've had a bike break on me!

I was riding my Linear recumbent on the Ottawa River pathway towards Brittania Park, and noticed the rear tire was chirping as it rubbed the frame. Stopped, tightened up the quick release, then kept going. The chirping returned, and so I figured maybe the hub's bearing adjustment was coming loose and causing the wheel to move laterally. So I stopped at the park and flipped the bike on its back (not the smoothest manouvre with that long frame and tailbox). Sure enough, the wheel had some lateral motion to it, but not due to a loose hub. It was due to a rather long crack in the left chainstay!!



This occurred right behind the reinforcing U-plate that joins the two stays together, right where they connect with the main frame (they attach with two quick-releases, because the bike folds at this juncture). This is also right under the seat, as all my weight is on this point, and I guess nine years of that stressed things a bit too much.



Since I was about 12 km from home, I had to decide between calling a cab (and subsequently folding and half-dismantling the beast to fit), or trying to ride home. I figured I'd see how far could get riding, and was actually able to make it back home in one piece, though I of course slowed down greatly for any bumps and dips, and grimaced as I went over them.

I now have three options, because since this broken rear end of the bike can be disconnected I can still save the machine: 1) Buy a new set of stays, but that would cost over $300US., 2) Make a new rear end out of steel, using the same design (welding pal Juergen gave a thumbs-up to this), or something incorporating suspension, and 3) scrap the bike and use the bits to make a new recumbent. Hmm...

The design of this bike has some issues that I'd heard about, and have now had confirmed. The original chainstay design consisted of flat aluminum stock, and the stays were apparently rather flexible. Mine has the second incarnation, where the plates have a shallow "V" formed through their middles for extra stiffening. But those have had their problems as well, and I know that the current builder has a new design in the works (the original company is out of business, but the name and design have been revived by Peter Stull of the Bicycle Man). There have been two other issues with my bike over the years. The first happened when the bike was two years old, and that was a crack in the weld where the BB shell fits into it mounting plate, causing much creaking. That whole unit was replaced under warranty by the original company, but it took six months to get done.

The second was potentially very dangerous. Since the bike has under-seat steering, a rod is needed to connect the steering bar to the front fork. This is done by way of a telescoping tube, and the inner, front section is drilled with holes so that one can adjust the length of the whole rod (to fit riders of different sizes. The seat slides fore and aft as well). The holes are for fitting a pin that backs up the clamping mechanism, and this rod is hollow, so the many holes definitely compromise the strength of this tube. One day I was arriving home and as I came to a stop the steering came loose in my hands. I kept the bike upright and thought "wtf?" I looked down and there was the front, inner tube, snapped in half through one of the holes! If that had happened at any speed I would have instantly lost control of the bike and crashed. I got rather angry at the stupidity of this design, and since the company was gone at that point I had to deal with it myself. I bought a new solid bar of aluminum, and simply drilled one hole where it was needed. That has held up just fine over the past three years. I posted this idea to the Linear listserv, and mentioned to Peter that this is something he should keep an eye on as he works to improve the bike's design.

I have loved the comfort of this bike, and that comfort has allowed me to do a lot more cycling and for greater distances than any of my upright bikes. So I still want to have a recumbent bike, but will take my time to decide if this one will live again, or get turned into another one.

3 comments:

Mike said...

Here's another of a cool mailbox I found while biking to Kingston.

dennis said...

About the linear, before you give up on it, I would find either an auto body shop that does custom aluminum welding with an acetylene torch or try the local experimental aircraft association chapter and ask if anyone is skilled with torch welding aluminum. This is a skill that few have and someone who thinks they might be able to... probably won't, but a person who can do it could repair your frame.
dennis

Mark said...

Dennis, my friend Richard took the cracked piece to a welder we know. He's the same guy that does Mike Watson's bikes (like my chopper), and he said the piece is fixable. My concern is sure, he can fix it, but how do I know the other side won't crack at some point? I think a new, stronger section would be best. Hmm...