Dogmans mixte cargo bike. (long tail)

[Voltron]

I know what you mean about the frame flex. I was thinking the same thing about the Xtracycle, and The Yuba Boda Boda, Thats another thing I like about my first gen Mundo, it seems way stiffer with the thick wall mild steel than the later thinner Chromoly ones when they started trying to cut the weight. The best feeling one so far I've felt was surprisingly the Yuba Spicy Curry.. that thing is stiff, and it has pretty thick wall alloy tubes and a custom 1.5" steerer tube... very little front end flex when you purposely start waggling the bars around at speed.

 

[amberwolf]

Regarding the twisting that happens in the front triangle between the front wheel and the rider, yeah, that can affect handling and stuff, and is one thing I keep wanting to fix on CrazyBike2.

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Note that stiffness does not necessarily equate to frame strength. A frame that can flex in the right way acts as a suspension of sorts to the loads it bears, and a frame that cant' flex is much harder on the anchor points of the loads, such as wheels/dropouts, seatpost mounts, cargo mounts, etc.

Some of the experiments I've done with CrazyBike2 to stiffen things up to prevent flex that derailed the middrive chains ended up causing the frame itself to fail under cargo/rider loads, in a different place than the stiffening. Then more stiffening in those areas was required, and then more in other places, etc etc. :/

It depends on the design of the frame itself, as well as the materials used, but sometimes frame flex is a really good thing.



Another note on flex: I originally intended to heavily stiffen up the SB Cruiser trike frame, laterally, but found that it's flex/twist is a good thing, because it helps as a form of suspension allowing the wheel opposite a bump or hole to stay where it is and toss me and the load (dog, cargo, etc) around less than if it were so stiff that it just tossed the whole back end up and down on those bumps/holes when only one wheel at a time does so presently.


On a fully-suspended vehicle, with good damping and whatnot, it wouldnt' make so much difference--but on one with no or non-full supsension, frame flex could make a big difference between breaking the frame over time or just absorbing some of those shocks.

 

[amberwolf]

Then decision time, Make it pretty with shiny red paint, or leave it all raw and rusty. Ugly has it's virtues, when parked at the store.

If it was really big and heavy, it'd be nice to have it pretty. Too hard to ride off with or carry away, so the attractiveness wouldn't be as big a target-maker.

But sometimes, ugly just wont' hide a target, if someone knows what the target is worth.

I do have a feeling that the more unique-looking something is, the less likely the typical thief is to want to make off with it. Too easy to get caught with it.

 

[dogman dan]

That's kind of my thinking too. Even prettied up, its clearly not a real easy thing to fence, except as loose parts stripped from the frame.

Best defense still shopping during the old fart hour at the grocery. Tweakers not up yet.

Leaning toward some nice shiny red paint, mostly because I have some. Or maybe a bright yellow.

Re the stiffness, a big part of that problem of moving a weakness over to another part of the frame should be eliminated by the frame design. But I came very close to making another frame like your trike.

 

[dogman dan]

Finished the bike today, except for minor mods like getting some mirrors for it. For now at least, flat black primer. It hides the "monkey on LSD" welding better.



It really does ride sweet, though slow. With 48-14 gearing, pedaling it is very slow, about 15 mph. I can put a 56t front crank on it, but that will cost me a lot of the rear battery tray. The chain will go through much higher, and start rubbing unless I add an idle pulley to bring it back down.

This is the slow, Heavy Duty E-bikekit on it, so it only goes 18 mph anyway. Never really meant for this bike to be fast. But the frame is so solid it could.

 

[Voltron]

That's got to be a nice feeling seeing it go from sketches to a fine looking roller...

 

[spinningmagnets]

Actually good looking, too.

 

[dogman dan]

Yeah, better looking than I expected really. But plenty ugly if you get close enough to see the welds.

The first cruise through the flea market yesterday. Priceless, the heads turning. WTF is that! And the look, I want one.

 

[SkyknightJohn]

8) Thumbs Up!