Bicycle Mechanics - Min wall thickness to thread threadless fork?

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Ink
10-04-05, 07:35 PM
I have seen several references in other posts to information on Park Tool Web site that spells out minimum fork tube wall thickness needed to allow safe threading of a threadless fork tube (assumedly using their threading tool).

Perhaps their Web site has changed, but I can not find anything like that in the documents now available.

Anyone have a pointer or pointer to equivalent reference info?

Thanks,

J

sydney
10-04-05, 08:38 PM
Steel steerer: 1" od needs an ID of 22.25- 22.3mm and 1.125" OD needs ID of 25.55-25.6mm Numbers from Park.
Ink
10-05-05, 12:35 AM
Steel steerer: 1" od needs an ID of 22.25- 22.3mm and 1.125" OD needs ID of 25.55-25.6mm Numbers from Park.

Thanks. I think one of your earlier posts was where I spotted the Park Tools reference.

Time to take this affair to my machinist and let him whip out his micrometer.

(edit: Well, just took my not-very-spendy calipers and ID of his 1" tube is consistently 7/8", so almost exactly 22.25. so worth taking it to the shop. The plan would be to thread it down no more than absolutely necessary. We'll see!)

J

HillRider
10-05-05, 10:56 AM
Threaded fork steerers have to have an ID compatible with a quill stem and its 22.2 mm OD. The steerer's OD must be 25.4 mm so that pretty well defines the wall thickness. A threadless steerer has the same OD requirement but the ID is not so critical and the wall thickness can be more or less.

It sounds like the fork you have was sized to be sold in both threaded and threadless form.