Bicycle Mechanics - Steerer Tube Length Question

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robbied196
09-19-12, 02:13 AM
I've got a Vitus 979 frame which needs some forks.

The headtube length without any bearing cups is 150mm.

Will a pair of forks which measure 162mm from fork shoulder to top of the steerer tube and 142mm from the shoulder to bottom of thread fit ok?

The thread is 20mm long.

Thanks for any help :)

Airburst
09-19-12, 03:37 AM
It's pretty questionable. You've basically got 12mm of space to play with, which I'd say is unlikely to be enough for a whole headset.
robbied196
09-19-12, 04:00 AM
It's pretty questionable. You've basically got 12mm of space to play with, which I'd say is unlikely to be enough for a whole headset.

Thanks Airburst, I thought it might be to short. I'm not very up on headsets so wasn't sure how much space they needed. Back to the search!

cny-bikeman
09-19-12, 07:12 AM
It's straightforward:

Head tube length + Headset stack height (easily looked up or measured) - 2 mm (space below headset locknut) = minimum fork column length (top of fork to bottom of lower race seat).
JohnDThompson
09-19-12, 01:14 PM
You choice of headset will determine how long the steer tube must be. Typical stack heights for headsets range from about 30mm to 44mm, so your steer tube must be longer than the head tube by at least that amount. If the steer tube is longer, it can always be trimmed, but too short is always too short.

http://www.os2.dhs.org/~john/stack-height-1.jpg