Rayxt

Has anyone ever put an accelerometer on the back rack? to see the kind of g-forces anything you're carrying is subjected to.

If you wanted to terminate your laptop in many ways, this would be a good place to do it.

beingtxstate

I use a laptop sleeve in a cushioned bag, and have for a long time with no ill effect to my PC. So did you use an accelerometer? What are the results? I'm not trying to be snide here, but I would venture to say that for most average commuters, assuming we don't fall, never achieve high enough stresses to harm properly stowed and stored items.

Actually, that is a good poll question...I think I'll start it...thanks

JanMM

You wouldn't want a hard drive to be running while you are riding - that would be a risk factor for damage. Ha ha. Here's another poll question: How many operate their laptop while cycling? Hope the answer is zero.

Artkansas 

In one job at a defense contractor, I used to carry electronic components (high level IC chips) between company sites on my bike. After a number of component failures of components strapped to my bike and zero failures of components in my backpack, I took the hint.

supton

I know on some of the equipment at work that gets shipped has little vials that are sticky'd to the side; inside it is either a split compartment or two different colors. If the g-forces exceed some point (and I believe there are different kinds of these items), the vial breaks and somehow shows that. I don't know if they sell them over-the-counter at UPS or the like, but perhaps you can find them on the web.

Like this:
https://www.lpsind.com/DropTell.htm
https://www.lpsind.com/Shockwatch.htm
https://www.labelslabels.com/scripts/...?idCategory=42
https://www.bottomlinepackaging.com/m...tors/drop.html

I wound up seaching for "buy shipping damage indicator". The last link seems to have a box of 25 for $87--kinda pricey, but cheap compared to what a laptop costs.

bigbenaugust 

I'd like to see anyone whip out a 17" Dell boat-anchor while riding. It might fit across the handlebars.

Seriously now, I have carried a couple of laptops in panniers and had no ill effects. The backup tapes (LTO-3) from work also seem to do okay.

Rayxt

Let's look at 'g-force' another way.

It's not the back tire going INTO a hole that does the damage (by exerting acceleration = to g), but COMING OUT of it. ie if you're riding at 20mph and you go over a 1 inch bump, the rear wheel will be elevated 1 inch in maybe a 50th of a second. I'm guessing here, but it is exceptionally fast, exerting an acceleration many times more than 'g' - like it was hit with a heavy hammer.

Just imagine riding over cobble stone streets at 15-20 mph (and there are many people doing it every day in Paris) what a pounding the wheels and frame take. New York City streets must be an adventure in vertical acceleration all on their own as well. Why fat tires are the order of the day. Not too many 700x20mm or even 26x1.5" in NYC I guess

AEO

This is what happens when you hit a pot hole and your rack uses weak metal and bindings....
I had about 3kg on one side only when it bent.

Rayxt

There you go! What happened was the 3Kg was dropped ( at 'g') on the rack supports, and an instant later the supports were driven into the 3Kg when the wheel climbed out of the hole, at many times 'g' force - like using a sledge hammer on it.

If you had tried to 'deform' your rack 'by hand' you would have had a real job to do it.

I hope somebody can get hold of an accelerometer and publish the results

bindibadgi

Wow. I've never had that happen and I've ridden on rocky roads at over 30mph before. Scary as hell but the only thing I've broken is a derailleur. And I had a week's worth of stuff on the back rack too.

Must have been one mother of a pot hole!

AEO

Actually, this rack holds up nicely when you use a stronger support bar. I think the P-clamps slipped and allowed the triangle to deform. You can see the bars coming off of the bolts.
The pot hole made the 3kg go down and forward, which made the P-clamps slip and squished the bars. the rack leg took a bit of the brunt I guess.

I fixed her up by adding washers to the nuts so the bar wouldn't slip off like that, using stronger bars off another rack and using it on my miyata which doesn't require P-clamps.
I still use the rack, just not the bars.

bindibadgi

The bars do look like the weak link there. Let's hope it doesn't happen again!