Failure Analysis of a Cracked Frame - Recommended Steel Cruiser (Feet Forward) ?

markz

markz

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What do you guys recommend for a steel, cruiser, feet forward bicycle?

Here is my beloved blue Townie Electra 21D that I was going to paint black.
Remember I am 375lbs, plus battery & controller on that top bar.

When I was looking at it from the top (Pic 4) I am like no way, the guy that stole my battery also tried to steel my bike.
But it was that brake/gear hole in the frame that did itself in.

Currently riding a wimpy 500W front motor on a CCM, due to smoking my mxus 3kw, stalling on a hill, mustve been delirious from the heat that day, plus no chain :( to help out .
And to think I was going to buy another 21D without knowing what happened to this frame.


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What sat in that location, was a battery. In the last rendition there were 4 Ryobi 6Ah, previous renditions various builds of 5 Makita (5S2P) and two of those, while the third sat up near the headset, controller was always on top.

So a combination of obviously my weight, plus the weight of the battery. When I smoked the motor, I took the bus home so a couple big bumps added in for flavor.

I never jumped this bicycle at all, just normal curb action, never too fast as I was too afraid of losing a millionth inner tube.
 
I guess that top bar just isn't meant to support a load like that. Normally that tube is under compression, but not supporting a vertical load. Your weight (on the seat) is transferred straight down to the bottom bracket, so not on that bar.

But that bar seems to be curved, which also seems like a less than ideal design. Triangles are strong, that isn't a triangle though.

Plus that's a god awful bad place for a hole. I'll take looking at some cables over having a hole in my frame any day.

On the whole, I'd say that's just a bad frame design. I'll know to warn anyone considering buying it.
 
You should get a yuba mundo instead. They're rated for something like 500lbs+. There are other shorter cargo bikes that are rated for high weight too.
 
I was thinking about getting someone to weld 'er up 4 me.
I just have an Arc welder and haven't welded aside from a few practice beads.

Drunkskunk said:
Zize makes a bike that can handle 500 lbs, called the "A New Leaf", but it's not a feet forward stye and it's stupidly expensive. Not many other choices for bikes rated for more than 350lbs.

How's your welding skills? Can you replace that tubing with some thicker wall 4130?
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Yeah well obviously a combination of events added to its failure. I've been thinking about it, and another factor would be after taking the rear motor off, and storing the bike in the garage, it fell a half dozen times so the very minor shock value of the handle bars hitting the concrete floor would have added to the crack.

The only thing I see probably happening is a small hairline crack started, whenever that was.
The bus ride home with the bike on the bus bike rack and taking a few bumps, which wasnt anything out of the ordinary.
The bike falling in the garage.
Both events is what did the bike in from in initial hairline crack.

Yeah the holes to hide the cables isnt ideal, but this is a cruiser for casual riders of normal weight that ride for a dozen or 2 times a year.

Now on the hunt for a steel frame with no holes in frame.

dustNbone said:
I guess that top bar just isn't meant to support a load like that. Normally that tube is under compression, but not supporting a vertical load. Your weight (on the seat) is transferred straight down to the bottom bracket, so not on that bar.

But that bar seems to be curved, which also seems like a less than ideal design. Triangles are strong, that isn't a triangle though.

Plus that's a god awful bad place for a hole. I'll take looking at some cables over having a hole in my frame any day.

On the whole, I'd say that's just a bad frame design. I'll know to warn anyone considering buying it.
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Gracias amigo, I will take a look at the Yuba Mundo.
I like the Compact Cargo bikes from them. https://yubabikes.com/product-category/compact-cargo-bikes
Boda Boda All Terrain @ $1899 new welded in rear rack is a nice feature.

neptronix said:
You should get a yuba mundo instead. They're rated for something like 500lbs+. There are other shorter cargo bikes that are rated for high weight too.
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markz said:
Yeah well obviously a combination of events added to its failure. I've been thinking about it, and another factor would be after taking the rear motor off, and storing the bike in the garage, it fell a half dozen times so the very minor shock value of the handle bars hitting the concrete floor would have added to the crack.
Click to expand...

Maybe. Or maybe the regular loads you were putting on the bike made this failure inevitable.

markz said:
Yeah the holes to hide the cables isnt ideal, but this is a cruiser for casual riders of normal weight that ride for a dozen or 2 times a year.
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Right. We've discussed drilling holes in frames here a few times. And while it seems like you can often to it and get away with it, it has always seemed like a questionable practice to me for an ebike that will probably be ridden more often and go faster than the maker ever expected.[/quote]

markz said:
Now on the hunt for a steel frame with no holes in frame.
Click to expand...

The feet forward position is going to make it tough without doing some kind of customization. I was thinking about a bent seatpost, but given your weight, I think that is just asking for trouble.
 
Maybe this seatpost could give you the feet forward position on a regular frame ... and survive.
http://store.ruff-cycles.com/ruff-cycles-bicycle-parts/seats-co/ruff-cycles-layback-seat-post-heavy-duty-cp.html
ruff-cycles-layback-seatpost-cp.jpg


It may also be worth looking that this frame of theirs - and others.
http://store.ruff-cycles.com/ruff-cycles-bicycle-parts/seats-co/ruff-cycles-layback-seat-post-heavy-duty-cp.html
ruff-cycles-frame-dean-se-v3-3.jpg
 
I have bent a way-way-layback seatposts, it even had the extra bar.
I am going in that direction, but my own design with steel from the metal store.
I wont go as far back in terms of seat to crank distance. Then the wheelbase may have issues, like too easy to do wheelies.

I am contemplating two bicycles, one a used Schwinn 5 Star Cruiser because its a 1x6spd, but orig from CT department store. If its steel then I may go for it. What threw me off is the ad has an old 1976's white Schwinn lettering on a black background, but the bike has V-brakes which came out in 1996 after Schwinn gave away its name for $ from dept stores.

The 2 top bar cruisers are what I am after.




wturber said:
bent seatpost, but given your weight, I think that is just asking for trouble.
Click to expand...
 
Can't help you with the Feet Forward Feature, sorry.

You should definitely look into any kind of utility bike or expedition bike. These bikes are made to take a beating and with a rider of your weight going down a curb is a beating on a frame.

Surly Troll, Ogre, ECR, Big Dummy, Big Fat Dummy
Salsa Blackborow
Workcycles Fr8, Gr8
Any form of cycle truck
Yuba was already mentioned
Kona Ute
Thorn Nomad
Velotraum VT-900, VT-1100

There are way more. These just came to mind first.
 
The plan is to find a decent brand name steel frame like shown below, trying to stay away from department store BSO's.
Then fabricate my own wayback seat post, that is uber reinforced.
 

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wturber said:
Or maybe the regular loads you were putting on the bike made this failure inevitable.
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That's what caused the keel tube breakage on SB Cruiser a few weeks ago. (only thing that let me ride it home was the subframe that holds the IGH happened to cross the break in the keel, holding the trike front end on enough to get home).

wturber said:
markz said:
Now on the hunt for a steel frame with no holes in frame.
Click to expand...

The feet forward position is going to make it tough without doing some kind of customization.
Click to expand...
There are some. I have a cruiser type frame with built-in rack, Schwinn something. Cant' remember what the name is on the frame; will have to go look when I don't have a couple hundred pounds of dog helping gravity keep me in the bed. :lol:

However, I can just about guarantee it's not designed for that much weight. Might still hold it, but couldn't say how long.

If I were building a bike frame for that kind of weight, I'd make it all straight line triangles, no curves, and make sure everything is fully triangulated, perhaps even with gussets at the intersections.
 
wturber said:
Maybe this?
https://www.worksmancycles.com/m2600.html
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Those look pretty well made. I wonder what the dropout spacing is. Looks like the upgrades to make the bike capable of 500 lbs are tires and brakes, so the frame itself should be capable. I like that other model, the "Atlantic Coast Cross Cargo Cruiser", because it looks like the standover height is lower. It has the same note on the 500 lb upgrades. (just noticed, no room for the battery).
 
If you attempt to salvage that frame, cut out that gobshite top tube, and replace it with a good chunk of like 1 1/4 by 2 by .065 or maybe .080 wall rectangular tube, have a metal shop till it to the rough shape of the old one and weld it in for you. Probably cost you about as much as a new frame.
 
Oops, just realized i double posted that...
A new frame is probably far better a choice now that I'm thinking on it. Those Worksman bikes look nice.
 
markz said:
The plan is to find a decent brand name steel frame like shown below, trying to stay away from department store BSO's.
Then fabricate my own wayback seat post, that is uber reinforced.
Click to expand...

I'f it weren't for those slots in the top tube, I suspect that bike frame would still be doing fine. I suspect that any well made frame in good shape would probably outlast the one that failed by a good bit. I think something like a CrMo steel Trek 820 (very commone and inexpensive) is really all you need. But whatever you get, make it a point to pad anything you connect to the frame so that clamps don't gouge or score the metal frame.
 
I am not that rich, and besides I need something that will fit in the bus bike rack, the Townie Electra just barely does.
 
markz said:
I am not that rich, and besides I need something that will fit in the bus bike rack, the Townie Electra just barely does.
Click to expand...

I just picked up a 1995 Trek 990 frame today for $35. It gets no style points, but it is a pretty sturdy steel and high quality steel frame. It is in the same vein as the Trek 820 I mentioned earlier except that is about ten years older and doesn't have the fat top tube of the 820.
 
Yes, I am on the hunt for that type of bicycle. Just did a round of "Trek" and "Giant" searches on the ole Kijiji app/site.
A good brand name steel frame that I can weld to :thumb:
That is cheap :thumb:
Has an anti-theft aspect to the vintage and look :thumb:
Which means no one will look twice at my ride :thumb:



wturber said:
I just picked up a 1995 Trek 990 frame today for $35. It gets no style points, but it is a pretty sturdy steel and high quality steel frame. It is in the same vein as the Trek 820 I mentioned earlier except that is about ten years older and doesn't have the fat top tube of the 820.
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markz said:
Yes, I am on the hunt for that type of bicycle. Just did a round of "Trek" and "Giant" searches on the ole Kijiji app/site.
Click to expand...

The Trek three digit models are made of steel. So Trek 4xx, 5xx, 6xx, 7xx, 8xx, 9xx. The higher the number in a series, the generally higher quality or more race oriented is the frame and the better the components. For instance, the 990 is triple butted while the 920 is not. So they tend to be lighter and probably stronger. For instance, the 990 has an added reinforcement plate where the top tube joins to the head tube. But the butting may or may not be desirable If you ever want to weld towards the middle of the bike tube - especially since saving a pound or two isn't your priority

Also, the lower number models will be cheaper. I found a complete 2005 820 (well, almost - it had rims but no tires) for $75. A complete 1997 Trek 720 for $65 (though it has some funky 28" rims - a size I'd never heard of). But the frame only 990 cost $35. The lower numbered bikes are, of course, more plentiful. The newer mountain bike framess tend to have fatter and sometimes shaped tubes.
 
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