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a.k.a. BicycleKicks
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Discussion Starter · #1 ·
Assume you have two stems such as the ones shown here with the same geometry. How important is the material to choosing which one to use? I bought the road version of this stem on the advice of a store manager (since they actually don't make the mountain version in the length I want).

mountain material = 6061 alum
road material = 2014-T6

Will the road version snap or something?

Also, any reason why one clamp design would be better than the other for a carbon bar?

Font Black Bicycle accessory Machine Bicycle part

Bicycle accessory Bicycle part Line Font Bicycle stem
 

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Former Bike Wrench
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Many road stems are built lighter, but if they are the same weight (+/- 10 grams) then they will be generally equal in strength. Road stems tend to have more rise/drop than mountain bike stems and the standard bar clamp size is generally different. But with oversize 31.8 it is the same so they can be intermixed.
 

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+1 if the clamp system is similar and you're going with 31,6 either way buy the geometry you need and don't sweat it.

BTW- are you sure the specs. are right?, T6 condition is common with 6000 series alloys and less so with 2000 series. Here's a general reference for alloys and tempers if you're interested.
 

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to further elaborate on FBinNY's link for stems, handlebars, and seatposts (not frames)

-2XXX series alloy is usually mid level parts, lighter than 6XXX series but heavier than 7XXX series
-6XXX series alloy is usually either low end or heavy duty parts, tends to bend rather break catastrophically...most of the time
-7XXX series tends to be top end alloy parts, highest strength to weight ratio of the three so it can be made to near carbon fiber weight. Tends to fail catastrophically though.
 

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a.k.a. BicycleKicks
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Discussion Starter · #5 ·
FBinNY said:
+1 if the clamp system is similar and you're going with 31,6 either way buy the geometry you need and don't sweat it.

BTW- are you sure the specs. are right?, T6 condition is common with 6000 series alloys and less so with 2000 series. Here's a general reference for alloys and tempers if you're interested.
Here's the link to the road version... http://www.performancebike.com/bikes/Product_10052_10551_1033000_-1_400022_400002_400207
It says 2014-T6... not sure if it's 100% accurate, but I guess we have to assume it is.

and the mountain version... http://www.performancebike.com/bikes/Product_10052_10551_1032995_-1_400021_400002_400204

[I hope the links work]
 

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a.k.a. BicycleKicks
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Discussion Starter · #7 ·
shiggy said:
What diameter is your bar? The linked stems are 25.4 (mtb) and 31.8
31.8... so it wouldn't matter if the mtn stem came in the length I need anyway, it wouldn't work. Thx for pointing that out.

Anyhow, it's really the material debate and clamp design info I'm interested in. Sort of an academic exercise I guess.
 

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xx = xtr²
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2014-T6 aluminum is way stronger than 6061-O alloy.

The yield strenght (amount of pulling force needed to permanantly stretch the material) of the 2014 is 60,000 Psi and the yield strenght of the 6061 is only 8,000 Psi

The 2 alloys weigh almost the same so the 2014-T6 can be made lighter that the 6061 one as it's strenght will not be compromised.
 

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Zakarina said:
2014-T6 aluminum is way stronger than 6061-O alloy.

The yield strenght (amount of pulling force needed to permanantly stretch the material) of the 2014 is 60,000 Psi and the yield strenght of the 6061 is only 8,000 Psi

The 2 alloys weigh almost the same so the 2014-T6 can be made lighter that the 6061 one as it's strenght will not be compromised.
Not that it matters, but your numbers seemed way off to me. I couldn't believe a 7:1 ratio of comparable strengths, so I thought I check with a reference. Be sure to scroll all the way down to the disclaimer at the bottom of the page.

Sure enough the difference is much smaller. The actual heat treat, and other considerations will make for some variation, but these are better numbers for comparison purposes.

Don't go crazy trying to be a metalurgist, since material strength considerations were factored into the design by the makers, so stems of either material will do the job. Buy the right clamp, length and rise, and the stem, not being too bright, won't care what kind of bike it's on.

As a rule MTB stems will be made stronger (though possibly heavier) to allow for the greater twisting forces longer handlebars make possible, though even that assumption is open to challenge. In any case stem breakage (in alloy stems) isn't that a common an occurance.
 

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xx = xtr²
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FBinNY said:
Not that it matters, but your numbers seemed way off to me. I couldn't believe a 7:1 ratio of comparable strengths, so I thought I check with a reference. Be sure to scroll all the way down to the disclaimer at the bottom of the page.

Sure enough the difference is much smaller. The actual heat treat, and other considerations will make for some variation, but these are better numbers for comparison purposes.

Don't go crazy trying to be a metalurgist, since material strength considerations were factored into the design by the makers, so stems of either material will do the job. Buy the right clamp, length and rise, and the stem, not being too bright, won't care what kind of bike it's on.

As a rule MTB stems will be made stronger (though possibly heavier) to allow for the greater twisting forces longer handlebars make possible, though even that assumption is open to challenge. In any case stem breakage (in alloy stems) isn't that a common an occurance.
I'm sorry, but your reference is about 6061-T6 aluminum and not 6061 like the stem of the OP. I should have posted my references in my original post, here they are:

2014-T6: http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA2014T6
6061 : http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6061O
 

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from what i remember ,i saw a chart in a cataloge where i used to buy billet.Compared to 6061; 2024 is about 33% stronger, 7075 is 50% stronger than 6061.2014 is fairly close to 2024, the corrosion factor that is mentioned in those linked charts.I have a deda road stem that is finally retired after it started to literally crumble around the steerer clamping bolts.
 

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Never trust a fart
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The Forte OS Road stem works fine in a MTB application. The MTB stem uses the 25.4mm clamp size. I've installed both on road and mountain bikes without issue.
 
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