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Sunday, September 13, 2009

Bike Diet

Since so far all I have had is estimates of total weight based on various component weights, some of which themselves were estimates, I finally got tired of the guessing game on weight, and set the bathroom scale so I could put the bike on it upright resting on the rear ends of the cargo rails. I could barely hold it in place and still read the scale, which kept wiggling between 140 and 150 pounds, including my toolkit, air pump, and a handful of bungee cords (probably 10 pounds at most).

So the bike weighs a LOT more than I had thought, since I was estimating roughly 120 pounds.

I'm guessing that the square-tubing I used for the seat mount and cargo top rails is much heavier than I thought (I never weighed it). Among other parts, I am going to see if I have bike tubing or something else of the right type to replace it and make it lighter.

That will save from 5-30 pounds, depending on exactly how much that square tubing weighs.

I am also going to cut the downtube of the rear frame off, along with the seat stays of the front frame and those ex-front-fork braces that go from the top of the seatpost on the rear frame to the dropouts of the front frame. That will be replaced with a reversed pair of chainstays welded to the rear BB so that their dropouts line up with the front frame's dropouts, and then I'll bolt those together.

That will save some undetermined amount of weight (maybe 5-15 pounds), and also clear up the middle of the bike frame for placement of stuff.

I'm also going to replace the MTB shock fork with a regular 10-speed fork, no shocks, very light, and then work out a headtube shock system with whatever I have on hand for later, which should weigh less than 1/2 of what that MTB shock weighs. (it's currently at least 10 pounds, maybe 15).

If I manage to take the max off of each one, that'll take at least 50 pounds off the bike. Even if it's just the minimums, it'll be at least 15-20 pounds. Any lightening will help my tires, wheels, and also make less work for the motor to do especially in acceleration. And less work for brakes to do.

While I'm at it, I'll see what brake system I can fit on the rear, because I've put that off long enough.

All these things won't happen at once, but over several days, since I need to use the bike a few days this week off and on.

Now, I *am* worried that this is going to weaken the frame for cargo capacity and whatnot, but really, the bike has always been too heavy, so heavy that it is a chore to pedal without having the motor and batteries on it--because apparently it weighs around 90-100 pounds BY ITSELF!

So it's time for the bike to go on a diet, and lose some weight. :-)

1 comment:

  1. That diet is a great idea! I estimate mine weighs about 70 pounds. My battery, being a riding mower type, weighs about 30 pounds by itself. The bike weighs about 30# if it were stripped to just its original condition. The motor/gearbox assy. weighs about 5-6#. The honeysuckle stick racks (front and rear) weight about 5# for both. The battery tray is two wooden slats (poplar taken from an old chest of drawers) and weighs about a pound.


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