Bicycle Mechanics - Bike Rack Bolt size (length)-How to measure length, to top, or only threaded?

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Snowsurfer
12-22-09, 12:07 AM
Quick question, when I buy bolts, does 20mm refer to the entire length of the bolt right up to the top of the head of the bolt?
Or does 20mm refer only to the length of the threaded portion?

operator
12-22-09, 12:07 AM
Threaded.
HillRider
12-22-09, 08:44 AM
For short bolts where the threads extend all the way to the head, the length is the threaded section. A bolt 20 mm long is in this catagory.

For much longer bolts where the threads extend only part way up the shank, you measure from under the head to the end.

Scooper
12-22-09, 08:56 AM
Measuring fastener length (http://www.boltdepot.com/Fastener-Information/Measuring/Measure-Length.aspx).
Snowsurfer
12-22-09, 12:04 PM
Measuring fastener length (http://www.boltdepot.com/Fastener-Information/Measuring/Measure-Length.aspx).

lol@ shoulder bolts length measuring

thanks for the link