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Who are the brain police?
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Why no Ti rims? Is there a reason?
 

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here today
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Perhaps ... From memory Ti is hard to work and seizes to tools when worked, strength varies from a value lower than st steel to about equal of anneal st steel (316) or CoCrMo alloy (cast ?). Good corrosion resistance, low density, about half of ss or CoCrMo - expensive and requires specific tools....
 

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They would simply be too heavy. Titanium is usually used as an alternative to steel, rather than aluminium alloys. You can use titanium, steel or aluminium for frames since you are not restricted too much by tube dimensions i.e you can use a small diameter steel, slightly bigger ti or even bigger aluminium tubes to achieve comparable strength/weight ratios. You can't really apply this concept to wheels since they have to be dimensionally similar. If you made a titanium rim dimensionally identical to an aluminium rim it would weigh roughly 1.6 times as much.
 

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"El Whatever"
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uktrailmonster said:
If you made a titanium rim dimensionally identical to an aluminium rim it would weigh roughly 1.6 times as much.
And it would be uberexpensive and not stronger than the Al wheel depending on the alloy. It would be more difficult to distort though as it's more elastic.
 

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Warp2003 said:
It would be more difficult to distort though as it's more elastic.
Are you sure that wouldn't be a better reason to avoid it for this application? Leave the "suspension" to the spokes, keep the rim strong. Titanium's natural elasticity would make me wonder about having a rim that would possibly need more maintenance.

That, or I need to stick with "naked chicks and beer", too. ;)
 

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No, titanium is strong, no doubt about it. It's also light. It's flexibility is looked upon in one of two ways - a blessing or a curse. The application is what determines it's usefullness. For a Lockheed SR71A "Blackbird" it's a blessing. For bike rims it's a curse.
 

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"El Whatever"
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cdub said:
so you guys are saying that Ti is not as strong as steel or aluminum? i just assumed it was stronger cause its so hyped about
What andrew said and Ti is more resistant over a wide range of conditions depending on the alloy. Temperature, aging, lifespan are virtues of Ti. That's why a frame made of Ti is marketed as "indestructible" or "lifetime".
 

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"El Whatever"
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scant said:
WHY NOT carbon? used on road bikes for a while. for disk brake equipped mtbs?
I've seen (think its extralite?) make a carbon rim wheelset, but it didnt catch on..
Because carbon shatters with impacts and impacts are very easy to get on the trail.
 

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I work in a fabrication shop and from what I have experience with, the following applies. If you took a piece of Aluminum, Magnesium, Titanium and mild steel of the exact same dimensions the weight would be from lightest to heaviest:
1. Aluminum - Light, easy to work with, easy on tooling. Stiff, doesn't like repeated stresses (fatigue life), not cheap but not expensive.
2. Magnesium - light, strong, hard to work with and machine, very explosive and flamable when machining, moderate fatigue life. Only beryillium is more expensive as far as metal fabrication goes.
3. Titanium - not as light, very strong, good fatigue life. Hard to work with and machine. Explosive and flamable when machining. Expensive.
4. Mild steel and variants - Heavier, strong, great fatigue life. Easy to machine and work with. Not much hazards associated with machining. Cheap.

I have been in the Boeing fabrication facilities watching some of their metal parts being made and most of the body is aluminum, with parts of the landing gear being Titanium or Magnesium depending on location and use. Their are uses for each material, it just depends on strength vs weight vs stresses and life expectancy. I do know that when they are milling titanium or magnesium, there are big time precautions taken to prevent fire and explosion. Hope that helps.

I think Magnesium would be a better substitute for Alumunim wheels as the characteristics are more similar. Although, the price would be outragous due to material cost and machining/fabrication complexities.
 

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Tim in WA said:
I work in a fabrication shop and from what I have experience with, the following applies. If you took a piece of Aluminum, Magnesium, Titanium and mild steel of the exact same dimensions the weight would be from lightest to heaviest:
1. Aluminum - Light, easy to work with, easy on tooling. Stiff, doesn't like repeated stresses (fatigue life), not cheap but not expensive.
2. Magnesium - light, strong, hard to work with and machine, very explosive and flamable when machining, moderate fatigue life. Only beryillium is more expensive as far as metal fabrication goes.
3. Titanium - not as light, very strong, good fatigue life. Hard to work with and machine. Explosive and flamable when machining. Expensive.
4. Mild steel and variants - Heavier, strong, great fatigue life. Easy to machine and work with. Not much hazards associated with machining. Cheap.

I have been in the Boeing fabrication facilities watching some of their metal parts being made and most of the body is aluminum, with parts of the landing gear being Titanium or Magnesium depending on location and use. Their are uses for each material, it just depends on strength vs weight vs stresses and life expectancy. I do know that when they are milling titanium or magnesium, there are big time precautions taken to prevent fire and explosion. Hope that helps.

I think Magnesium would be a better substitute for Alumunim wheels as the characteristics are more similar. Although, the price would be outragous due to material cost and machining/fabrication complexities.
Yes, that's well put Tim. Magnesium is often used in preference to aluminium for high end racing car wheels (cast or forged) and gearbox casings (cast and post machined). Magnesium is not very hard wearing though..
 

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Tim in WA said:
I think Magnesium would be a better substitute for Alumunim wheels as the characteristics are more similar. Although, the price would be outragous due to material cost and machining/fabrication complexities.
I think Mg has already been used in the "ergal" alloys of some bicycle rims... The old Fiamme "Yellow Label" rims were made of that alloy; very light and strong, but known to be somewhat brittle. Those Fiamme rims weighed 290 grams in a road bike sew-up size.

The were a couple of other vintage sew-up rims even lighter though.... One was an aluminum rim built on a balsa wood core; I think those were down to around 240 grams. Another was the old Hi-E sew-up - scary light at 220 grams. I've got a set of those built up with '70s Pino Moroni Ti spindle hubs & 15/17 gauge spokes...just to look at.
 
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