Archive | July, 2010

Bicycle Spreadsheet w calculations for Wind Drag and Road Grade

23 Jul

Some friends are doing RAGBRAI this summer, and one of them was asking about the differences between wind drag and road grade, so I put together a crude spreadsheet such that some scenarios could be run. Via my own experience, I’ve found that wind seems to be much more of a headache than a steep grade (granted, there are exceptions), so I wanted to see what some numbers might show.

The model is pretty crude, and a number of approximations were made for simplification purposes… Also, its not very user friendly, being I cranked it out so fast, thus a bit of textual explanation may prove helpful.

The key user entered variables are in light blue, namely total weight of the bike+rider+pack, windspeed, and the road grade. Windspeed is positive for a headwind, and negative values can be entered for tailwinds. The road grade or hill gradient is rise over run, with a typical max value of 0.12 rise/run which covers 95% of all roads.

The output of the model is located in the two columns names trained athlete and average Joe… which are color coded green, yellow, and red. Green corresponds to the ability to consistently maintain a give speed. Yellow is for short sprints, and red is pretty much impossible. The color shading changes based upon fixed values due to limitations of google docs speadsheet functionality.

The spreadsheet is open for anyone to modify, thus if you get some weird values, you may want to check the revision history, and revert back to the last version saved by me (mnphysicist).

You can access the spreadsheet at??

http://spreadsheets.google.com/ccc?key=0AjEwNba74LBgdE9OWEZVUVVZSVNGa3BtRFNkVUFfTEE&hl=en#gid=0

Nutek Bolt Off appears not lame….

16 Jul

A few weeks back, Ace Hardware was promoting Nutek lubricants… they were pretty much free after rebate, so I thought ok cool, anything is worth a try. As green as I try to be, I do hold to the impression that green usually equates to lame products that barely work. To add insult to injury, they packaged their product line in a tiny container, and didn’t even bother to add a nozzle tube… so I was figuring this would be a major flop, but hey at least it was free.

So, I had a trailer tire which needed changing, but it hadnt been touched since 1989… and has spent the last 20 winters outside, with some winters ending up with enough snow, that the snow plow actually covered the wheels. As such, corrosion city… I could barely see the threads on the stud. So… time to give this Nutek Bolt Off a shot.

I figured ok, this is a consumer product, its going to make a mess all over the place, and the nozzle tubes I had didnt fit. At least I thought, well if it dribbles all over, at least its green. I was surprised in that it actually shot a tight stream of liquid, rather than an aerosol. Granted, I would have liked more pressure behind it, but with careful positioning, it works pretty well. In a lot of ways, its better than using a nozzle tube, plus by designing out the nozzle tube, you can’t loose it. :_

So I sprayed the lugnuts, and then waited half an hour, sprayed again, waited another half an hour, and then tried to break the nuts loose. My compressor took a header, so all I had was a 18″ breaker bar… and well a seven foot square tube that I normally put over the breaker bar when I can’t break things loose. As I’d rather not replace studs, I always start out with hand pressure first, and then if that fails I the square tube, and then jump on it.

Surprisingly, 2 of the nuts came off just by using the 18″ breaker bar. 3 of the nuts took me standing on the breaker bar, but there was no need at all to jump on it, much less get out the 7 foot square tube. I’m amazed… this seemed to work even better than PB Blaster and JB80, my old standbys. As such, tomorrow I’m going to try it on a stuck Saab assembly and see how that works. If it does… they by golly, they may be approaching Kroil (which is amazing but near impossible to get retail, and very spendy too)

I think they have a winner, both in performance, and in the nozzle tube concept. Now, if only they’d loose the lame small package. Then again, there have been a number of times where I’ve fought stuck exhaust manifolds where there was no way to get anywhere close with JB80 even with a nozzle tube, so they may be onto something there as well.

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Telephone Ring Emulator

7 Jul

This is a nifty implementation, and it also includes off hook detect.

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1042,C1031,C1061,P1266,D4338

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