Sub 18 Pound SWB... in Steel?
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Sub 18 Pound SWB... in Steel?
Maybe.
One glance, and the observant 'bent homebuider will immediately recognize the potential here. It is a Haro Comp Extreme, The frame is TIG welded, Tange, double butted tubing with a bare frame weight of 2659g.
After a litle selective surgery, I was able to trim-off 1593g. As shown below, (with chunky, 57-406 rubber, wide rims and a 950g fork), it weights 5366g (approx. 11.8 pounds)
One glance, and the observant 'bent homebuider will immediately recognize the potential here. It is a Haro Comp Extreme, The frame is TIG welded, Tange, double butted tubing with a bare frame weight of 2659g.
After a litle selective surgery, I was able to trim-off 1593g. As shown below, (with chunky, 57-406 rubber, wide rims and a 950g fork), it weights 5366g (approx. 11.8 pounds)
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You have cut away a triangulated truss structure and left a tube that will have to work in bending, as it was never intended to work!
Potential?! Oh Yeah! Potential for disaster.....and much pain!
The next step should be the trash bin! Recycled please......
Potential?! Oh Yeah! Potential for disaster.....and much pain!
The next step should be the trash bin! Recycled please......
Last edited by AlexZ; 07-12-11 at 03:45 PM.
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I'd also have to say that it's gonna be way too flexy. -At least, for most typical-sized adults.
And did you cut off the top half of the head tube? You need to have the head tube ends cut perfectly squared to get the head tube bearings to work well....
And did you cut off the top half of the head tube? You need to have the head tube ends cut perfectly squared to get the head tube bearings to work well....
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a builder?
Since you failed to ask necessary specifics to make that assumption - i.e. tubing diameter, wall thickness, span length, rider weight and static and dynamic loading location, predicted torsional moments along its span, and CoM location, I'll assume the answer is NO.
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I rough-cut the HT length, then made a few finish passes on a Bridgeport Series I vertical mill. The ends are within .001" of parallel. Will that do?
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I would not want to ride a monotube with such a small diameter main tube. What is it - 1 1/8"? At my weight, I would probably have the frame bent within a week, assuming I could even keep it on the road while powering it up to cruising speed. But, maybe it will work for you. I hope it turns out; your bikes always look so nice.
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Interesting observation. Are you
a builder?
Since you failed to ask necessary specifics to make that assumption - i.e. tubing diameter, wall thickness, span length, rider weight and static and dynamic loading location, predicted torsional moments along its span, and CoM location, I'll assume the answer is NO.
a builder?
Since you failed to ask necessary specifics to make that assumption - i.e. tubing diameter, wall thickness, span length, rider weight and static and dynamic loading location, predicted torsional moments along its span, and CoM location, I'll assume the answer is NO.
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I'm really not interested in your haphazard supposition. So... either provide me with accurate FMEA data to substantiate your claims, or find another thread.
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It Looks Good "FROM WHERE I'M SITTING!!!"
will immediately recognize the potential here.
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From what I`ve read from you before, I`m surprised to see you working on a short bike. It does look like an interresting project though- sure hope you keep the build thread updated. I don`t see how you`re going to manage the steerer. Will you make a new fork, or do you have a way to extend the threads?
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screw it...build it, and let us know how it gets on !
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It's still too thin though. The seatstays I'm not sure, but the main tube, almost certainly.
And you have cut the head tube shorter than any commercial bicycle manufacturer is willing to.
Good luck.
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Nope.
That won't be a problem - the steer tube is 1.25" OD and if you look closely at the image, you'll see a factory gusset at the lower HT/main tube joint - much like a BMX.
Last edited by PaPa; 07-14-11 at 03:00 PM.
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Heck, I'm just interested in the final product and your pics. Sub-18 lbs in CrMo could be revolutionary if successful for the 'bent riders.
After cost, weight and perceived 'slowness' due to weight is probably the biggest detractor to the non-bent rider.
After cost, weight and perceived 'slowness' due to weight is probably the biggest detractor to the non-bent rider.