The Machined Death Of A Water Bottle

Sometimes, peculiar things happen to us. And we like to report it. Today's peculiar story to you is a minor tragedy to me. And there's an interesting causality to it, like all events in the world around us. Let me briefly show you causality.

I had a desire to ride my Trek T1 fixed gear bike for 2 hours today. I had an appointment in the afternoon so I was in a hurry to get out of the apartment in the morning and complete the ride before then. So I donned my cycling spacesuit and filled a single Camelbak Podium with some plain orange juice, sticking it into the seatpost's water bottle cage made by Profile Design (injection molded nylon/fiberglass).

Anyway, so I head off for the ride, cruising at a good cadence on 44 x 18T gearing. The road I usually start off riding on had some construction work on one side of it today. The modest traffic was being diverted to the other. I maintained my pace but rode over two unexpected depressions in the road. I believe those people were making road bumps of some sort and I take it that they usually begin life like that - a half done, torn section across the road about 10 inches wide and 1-2 inches deep before they're filled in with a mound of asphalt (??) I faced an uncomfortable, jarring ride over those two, risking a flat. Boom, and then... boom.

20-30 minutes later, I arrive at a local park slightly out of breath and decide to sip some of that juice. Now I have grown so used to grabbing the water bottle from out of the seatpost bottle cage that I usually don't fumble much and don't give it a second thought. This time, surprisingly, my hand couldn't grab onto a bottle. Hmmm....was it still there?

I get off the saddle to check where my bottle was. Yes, the bottle was there alright, but it was a strange sight. It looked exactly like in the second picture below, reproduced for you after I returned home.

This is how I remember having placed my water bottle before heading out of home to ride.

This is how I found it in the park.

Whoa, whoa, what's going on here. How did that happen?

Let's see. If you were really observant, you'd have noticed 4 different things from the above picture. Atleast I did in the park when I got off my bike to inspect my water bottle. Yet, they are all connected. We will then tie a common thread across them and look at causality. Let's look at the picture above again.


1) The bottom of the water bottle was finely touching the rear wheel and tire. No wonder I couldn't get my hands on the bottle. Its perplexing that I rode my bike for 20-30 minutes with a bottle touching my tire.



2) There was a pronounced crack on the upper stem of the bottle cage. Hmmm?



3) One of the two fastening screws of the cage is missing. Ahhh. Okay, so now we can tie a thread across 2) and 3). It perplexes me as to how and where the screw might have popped out. I cannot answer that with certainty. It may very well have been that I started off the ride without a screw and I hardly noticed it, which is even more perplexing because I'm observant about these things.



4) And finally....holy Vitamin C! My orange juice. Its....its...gone!



Can we tie a thread across 1) and 4)?

Well, it turns out we can. Let me show you the underside of the bottle. Look closely.

The tire machined away a small section of the bottle. All the orange juice quickly escaped through it, leaving absolutely nothing in the bottle but some orange soup with road grit.

I have been trying to come to terms with how this happened. Here is a plausible theory, supported by observation :

The density of orange juice with pulp is more than that of water, about 1.2 to 1.25 g/cm^3. Because I was missing a screw in the bottle cage, the weight of the bottle stressed the plastic cage so much that it cracked the stem and compromised its holding strength. When I rode over two significant depressions in the road, the bottle slipped out of the lower base support and contacted the wheel and tire. I was riding at about 17-18mph so the tire, with a certain angular velocity determined by the gearing, started rubbing away at the bottle, producing friction and heat. Some of the juice started leaking out of the micro-hole. As the orange juice slipped out of the bottle and onto the tire, it attracted grit and sand from the road. With all those particles sticking onto the tire, the tire was now a very good abrasive. As I pedaled, oblivious to the fact that the bottle was touching the tire, the tire had become a very good machining tool and shaved away a portion of the bottle, enough to get a clearance for the tire to pass unobstructed. Finally, when I stopped to check the water bottle at the park, all the juice was gone. The grit was stuck onto the tire.

Big things happen from a combination of little things, a train of events. It is interesting to be a casual inspector and study the hows behind these events. In this case, my haphazard use of a water bottle cage cost me a nice water bottle. Now to find out how I lost that screw......


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