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Old 04-22-18, 06:34 PM
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cyccommute 
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Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

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Originally Posted by sweeks
Titanium is recognized for its high strength-to-weight ratio (https://en.wikipedia.org/wiki/Titanium). Wikipedia gives its Mohs hardness as 6.0, while "steel" (type not specified) is 4-4.5 (https://en.wikipedia.org/wiki/Mohs_s...neral_hardness).
I don't think you have to worry about stripping a titanium bolt head. In my experience, I have not seen any distortion of hex heads torqued to 300-400 lb-in (bottom bracket bolts).
Steve
I don't know what grade bolts you are using but from my experience, titanium bolts used for bicycle parts are extremely easy to round out. I've had a number of bolts on seatpost clamps and stems from reputable manufacturers rounded out very easily...much more easily than equivalent steel and stainless fasteners. I've also been told by a machinist friend that titanium is soft but work hardens easily.

As to hardness, the Mohs scale is probably not the best scale to use. Bondhus allen wrenches have a Rockwell C hardness of about 80. Grade 5 (6AL-4V) titanium has a Rockwell C hardness of 36. The other grades range from Rockwell C 98 (Grade 2) to 23 (Grade 4). Most of the grades are softer than the Bondhus tool. Stainless steel bolts, which are what I typically use, have a Rockwell hardness of about 70. They are tougher in my experience.

Perhaps the manufacturers should be using a higher grade titanium fastener but my experience tells me to go easy on titanium bolts as they are easy to ruin.
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