why are super-record Ti UT crank-bolts reverse-threaded?

[wallymann]

just curious. what is it about the Ti spindle + hirth joint that require a reverse-threaded crank fixing bolt?

[wallymann]

to force incompatiblity with steel UT spindles:

"The bolt is reverse threaded so that it can't be used with the standard steel axles, because a chemical reaction between the Ti and steel could cause it to seize."

[JLP]

I always wondered about that.

[sw3759]

was always curious as well.i know a guy with the super record group on his Tarmac and when I mentioned the thread direction for the Ti crankset bolt he said he had no idea it was left hand thread.he asked me also and I had no idea why they did that

[oldpotatoe]

Originally Posted by wallymann

to force incompatiblity with steel UT spindles:

"The bolt is reverse threaded so that it can't be used with the standard steel axles, because a chemical reaction between the Ti and steel could cause it to seize."

Probably this altho when I install the ti bolt into ti spindle, I lather with antisieze. I'd do the same with ti-steel.

[tuscanyswe]

Originally Posted by wallymann

to force incompatiblity with steel UT spindles:

"The bolt is reverse threaded so that it can't be used with the standard steel axles, because a chemical reaction between the Ti and steel could cause it to seize."

Good thinking!

[FlashUNC]

Originally Posted by oldpotatoe

Probably this altho when I install the ti bolt into ti spindle, I lather with antisieze. I'd do the same with ti-steel.

You're not most people.

[Mark McM]

Originally Posted by wallymann

to force incompatiblity with steel UT spindles:

"The bolt is reverse threaded so that it can't be used with the standard steel axles, because a chemical reaction between the Ti and steel could cause it to seize."

Who knew? And here I've been screwing steel bolts into titanium and titanium bolts into steel for years, and never had any seizing.