Tuesday, August 18, 2009

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......

Do you have any stories to share? Write to me here.

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Zach said...

Something very similar happened to me during a circuit race. A 30 minute race with a loop that was, I believe, about 1.5 or 2 miles long. After the 2nd turn of each lap is a long stretch before making a right turn, and there was a huge pothole in the middle of it, or some sort of big bump. early in the race, I'd say the 2nd lap, I went over this bump and the water bottle got stuck just the same way as pictured. I noticed this and went to grab it to bring it back up into place and maybe take a sip. I ended up knocking the bottle out of the cage onto the road, almost taking out a few people behind me.

Up until this point I did not have a sip of water during the race, so I went the whole 30 minutes of racing without water, and have to say I felt the dehydration towards the end of the race.

Ghostsprocket13 said...

certainly something that can be looked at in the design of water bottle cages. you can't ask for too much with a plastic cage. its too compliant to hold a bottle with one screw on. this is a very interesting story, despite of that!

Phil said...

Interesting. I've always wondered how much heat these bottles can take. I usually drink out of my bottles in the office but am careful about pouring hot liquids (like coffee) as I think that it would destroy it so I use it only for cold or lukewarm water or an energy drink. I suppose the heat from friction between tire and bottle was above 100 deg C? Wonder where the melted material went? Could it contain BPA?

Anonymous said...

How come you didn't feel the tire scrubbing the bottle? I would...

Bennett said...

Looks like you lost some tire too.

Sven said...

"Now to find out how I lost that screw......"

Does it matter anymore? :)

Ghostsprocket13 said...

Ron - Sure that sounds valid. For the same price, or cheaper, you can get an aluminum bottle cage that does the job really well. I don't see how a few teeny grams here and there can make a big difference to performance.

Ron said...

Alloy : Super! I could really use that for grocery shopping.

Wilson said...

My guess is you can patch that hole up with some molten plastic and let it cool. Not tested it but try it out. I'd hate to throw away a bottle like that.

Ron said...

Wilson 2:03pm : If the hole was small enough, I suspect the surface tension of the liquid could have allowed it to stay in reasonably. This hole is too big and has rendered the bottle useless. You idea of using hot plastic to seal it looks like a messy job. I considered candlewax or something like that but I really don't want debris from the patch going into my drink, even if it works at all.

gsport george said...

"...The density of orange juice with pulp is more than that of water, about 1.2 to 1.25 g/cm^3...."


That seems massively unlikely to me, do you have a source? Dont Oranges float?

Ron said...

Gsport : Good question. Actually that is some fun science. Try removing the peel of an orange. It probably won't float as its more dense. Orange juice does not contain rind. Rind is thick and porous helping oranges to float because of pockets of air. The theory of why they float is consistent with that of pumice rock floating in water.

As to the value of 1.2-1.25, I picked that up from someone who already measured the density using simple Archimedes principle. See : http://wiki.answers.com/Q/What_is_the_density_of_orange_juice_with_pulp. I don't know what the errors are in his calculation but I judge it must be close to the density of water but still higher.

Anonymous said...

plastic cages suckkkk

victor said...

Density of orange juice? that is so nerdy.

Mac said...

Profile actually have a tiny yellow label attached to those cages (Stryke, formerly the E cage),not to mount them behind the saddle. They are too flexible/flimsy for that application. A reason we no longer even stock that cage (at our shop). Profile make more robust cage called "Kage"...it actually works pretty well for that application...and is cheaper too.