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I just bought Avid CODE brakes. It comes with a rotor (200mm). I checked the website and manual and I can't find out if the rotor is stainless steel or the titanium version.

How can I tell?

Information printed on the rotor.

200mm HS1
BOLT TORQUE 55in-lbs 6.2N-m
A01 SEP 11
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3 Answers 3

up vote 2 down vote accepted

Archimedes figured this trick out a long time ago. Place it in a measuring cup submerged in water to determine it's volume. Convert the volume to cm^3. Then weigh it, and covert to grams. Divide the weight by the volume to obtain the density. The density of steel is about 7.8 g/cm^3, while the density of titanium is about 4.5 g/cm^3. You don't have to be that accurate since the density of the two materials is so different.

Ok, after doing a little bit of research, here is what I found. On this site it lists the Titanium rotor, but when you read the description, it says:

Material: Alloy Rotor, Titanium Bolts

Also, I found this forum post that says they are probably not titanium rotors, but steel rotors with titanium bolts, which seems to fit well (well enough anyway) with the description in the store link above. Most likely what you have is a steel, or alloy (use the magnet test) rotor, with possibly titanium bolts. To test if the bolts are titanium, weight them in your hand against a steel bolt of similar size. The titanium bolt should be significantly lighter. Or you could use a magnet. But it's probably easier to just figure it out by feeling the weight then to go around searching for magnets.

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It is the bolts only! My existing bike has a titanium rotor. The bolts dont stick to the magnet. The new rotor, the bolts stick to the magnet! –  Valamas Jul 13 '12 at 0:50

If a magnet sticks, it's steel.

Happy riding.

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I liked Kibbee's weighing and measuring answer better. This way is for lazy poeple –  mkoryak Aug 12 '12 at 17:26

You know, if you take a 2 inch ball made of lead and a 2 inch ball made of brick and submerge them in water, they will both displace the same amount of water, since neither will float. But Ill bet their weights are worlds apart. You probably meant to say.."Place it in a measuring cup FLOATING in water", then you can figure out how much water they each displace.

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This looks like it's a better fit as a comment on another person's answer rather than answer in itself. –  jimirings Oct 2 '12 at 14:08

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