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Custom Frame Design


atomant
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I thought the problem with Titamium was that its to brittle. (Cue - your talking crap etc etc)

Yep I agree with you B40RT, BSA made a batch of titanium framed B50 motocrossers for their works team, and they all snapped - repetitive shock stress.

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Now a Titanium bash plate, that would sell loads if the price wasnt as much as the bike, should be easy..ish to manufacture and on the 4rt might even save some money in the long term. A 4rt plate even the 6mm ones only last about 3-4 months before they are well bent out of shape and hanging, get one priced up Atom,its a start anyway

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My brother had a pair if wheels with titanium spokes (racing cycle) very strong and light, but didn't like shock loads, as he found out.

This was at least 15 years ago, and I haven't heard much of this material being used in that application since.

I would agree, not a great material for wheel spokes.

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If you modelled a frame and tested its load characteristics, you would find just like a bridge, some areas would need more strength and some less depending on tension/compression criteria. Therefore, it would be possible to design maybe even a composite frame which would be a fraction of the weight of a current design.. but at a huge cost .. that's the downside :D

So maybe there is some middle ground, maybe designing a frame to fine tune current designs then manufacture in exotic materials. This would be expensive but not as costly as the above option.

i suppose after giving it more thought, if you compared it to the mountainbike market, where you can pick up a santa cruz frame for over

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Now a Titanium bash plate, that would sell loads if the price wasnt as much as the bike, should be easy..ish to manufacture and on the 4rt might even save some money in the long term. A 4rt plate even the 6mm ones only last about 3-4 months before they are well bent out of shape and hanging, get one priced up Atom,its a start anyway

We bought some titanium plate to make some custom footrest hangers and the plate was only 4mm thick, was about 8" sq and that little 'offcut' cost us

Edited by marky boy
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Yup, tis fine for me addict, but you would need 3 times that size to make a bashplate, plus 90% folks would not pay the money for the material cost let alone the bashplate, reckon you are like me in the minority then. Just look at the cost for the titanium future trial links,

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Yep I agree with you B40RT, BSA made a batch of titanium framed B50 motocrossers for their works team, and they all snapped - repetitive shock stress.

Many years ago, I had ocassion to talk with Jeff Smith about the Ti BSA frames and he said the Ti wasn't the problem, it was the welding techniques available. They would patch the failed welds in the field and they would just break faster. Not many high-level TIG systems to drag to the races in those days....:D

I know that Titanium is a highly reactive metal that forms compounds that can result in structure problems. When heated in the presence of air, the weld surface contains brittle carbides, nitrides, and oxides, each of which can reduce the fatigue resistance and notch toughness of the weld (Ti does not like to be scratched from what I'm told) and heat-affected zone (HAZ). You also need to flush the back of the weld of air (like stainless steel) to get a sound weld.

I had one of my CAW (Certified Aircraft Welder) buddies tell me that Ti needs the "white glove treatment" as Chlorine from the perspiration on your hands can create spot corrosion and lint-free gloves are often used after final cleaning, before welding, to get a top quality weld.

I think I'll stick with TIG and ChroMo steel, I don't think I ever owned a pair of white gloves....

Jon

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The biggest problem BSA had with the Ti frames was they tried to copy the steel frame. It is like with aluminum, you\'ve got to design for the material properties. Remember those early 1\" square tube aluminum frames on the roadracers, and how they quickly became large-section beams?

That left them with something that was very flexy - adequate for the 250 but on the big bike I think they often managed to throw the rear chain a couple of times a race due to the flex. As mentioned above, Ti is not the thing you want to try and fix in a muddy paddock.

A few days ago I ran across these photos of a prototype frame Antonio Cobas did for HRC/Montesa which should show that it is possible to do a tubular frame on a modern trials bike that is within the capabilities of many people to fabricate:

http://2.bp.blogspot.com/_ZhCWX6XiSjk/SShG...ROTO%202000.jpg

http://3.bp.blogspot.com/_ZhCWX6XiSjk/SShH...MontesaN4A1.jpg

http://4.bp.blogspot.com/_ZhCWX6XiSjk/SShH...ontesa-N4A4.jpg

If anyone is interested in the construction/design topic I\'ve run an email list on that subject for about 12 years now. You can sub to it here.

ETA: I don\'t know why the linked images aren\'t showing up so I\'ve removed the tags.

cheers,

Michael

Edited by AtomAnt
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I think I agree with Paul, sounds like a lot of work and cost for little gain. I don't see the point. I had a beta alp 96 a few years back and the frame was modified to move the foot pegs back. this worked well, inexpensive with improved handling characteristics.

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