Originally Posted by
cny-bikeman
Absolutely absurd idea. Let's take your videos first. In neither of those videos is the tape confronted with multiple angled and curved surfaces, nor the concentrated, periodic stress that occurs at a bottom bracket. In neither case is stretching of the tape a factor, nor is it measured. Yes, duct tape is strong, but it is also elastic to some degree. As for nylon rope, it also stretches, though admittedly to a very minor degree, and in any case has no relationship to duct tape wrapped around a BB, and neither does your initial feelings about trusting rope. Finally, the stress on the BB is not merely up and down, but also side to side and torsional, so the idea of holding the BB up against the seat tube is ludicrous.
You say you don't have time to go around checking bikes, but you do seem to have time to make multiple posts on how to avoid a new bike and to find duct tape videos. Find a shop that sells used bikes, or screen ads for the best looking 2 or 3 bikes and check them out.
Nylon rope can be made to be static or dynamic, the dynamic type such as used to catch the fall of live loads in climbing, is very elastic - which absorbs the impact forces during a fall and keeps humans from snapping in half - but it's very strong and practically never snaps itself unless in such applications unless it's cut (for ex. by contact with a sharp edge). Static rope is dramatically less elastic.
I have no issue with the elasticity of duct tape ... nor with an elastic bike frame. My concern for a quick & dirty repair didn't place rigidity as paramount. My concern was that the frame holds together to permit the bike to ride from point A to point B with a controlled failure, or at least a warning before catastrophic failure (the latter meaning the bike can no longer roll in a straight line with my weight of 135 on it). The bike's tube is completely severed, nonetheless the frame still functions. I was riding it with a broken tube for an indeterminate time period. Theoretically, I have no issue with a flexible frame and in practice I only have an issue with a flexible frame if it fails to ride and/or injures the rider. In fact, a frame designed with flexible connections at all frame joints (imagine a NASA designed frame with flexibility built into the joints) would not be an issue as long as it rode with a degree of control and with warning before catastrophic failure.
A
roll of duct tape is very strong: tearing, ripping, cutting, or shearing it would require huge forces. The idea of a swaged cable was to keep frame tubes from completely detaching from one another.
Yes, I've had the time to look and post online (Craigslist, bikeforum, & duct tape videos). That's interstitial activity. Making contact with, scheduling, traveling to, meeting with, dealing with the inevitable Craigslist flake quotient, and inspecting bikes is a much more time demanding process.
I'm not interested in buying a used bike from a bike shop.