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Installing threadless headset: ream head tube?

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Old September 23rd 09, 10:36 AM posted to rec.bicycles.misc,rec.bicycles.tech,alt.mountain-bike
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Default Installing threadless headset: ream head tube?

On Sep 20, 8:56*am, Still Just Me!
On Sun, 20 Sep 2009 01:28:05 -0700 (PDT), jay

On Sep 20, 12:05*am, someone wrote:
On 20 Sep, 07:52, Paul Conners wrote:

Instructions coming with Cane Creek S-3 headset more than suggests, they say
it is imperative that the head tube be reamed prior to pressing in the cups.
Is reaming standard practice when installing headsets?

Only when the frame builder hasn't.

This is an external set (ie, not incorporated type) with sealed bearings.
The frame is 6061-T6 aluminum with 1&1/8 inch threadless steer tube.

I know little about your specification, my comment applies to steel
frames and may be less relevant with your setup.

Well then just measure the OD of the cups @ 3 different locations &
average. Them do the same for the ID of the head tube. The
interference should be ~0.10MM. I.E. the OD of the cups should be
about 0.10MM larger that the the head tube. But make certain to
average both sets of measurements. An accurate set of vernier calipers
can be had for very little $, in case you don't own one, but are a
real pain to use for people much over 40 yrs old & very easy to make
errors with.
Good dial indicators aren't a lot more expensive & a whole lot easer
to read. However U are stuck w/ either inches or MMs & have to use a
pocket calculator to convert back & forth. In this age of stupid
American patriotism we haven't converted to a totally metric system
( "If inches & fractions & quarts, teaspones were good enough for our
fore fathers, then why should we, the greatest nation in the world
bother to change to accommodate 95% of the industrialized world?") But
I digress.
If we have to deal w/ both systems an electronic digital caliber makes
the most sense. I think I saw a Mitutoyo digital caliper of 6'" (more
or less the standard size) on sale for about $100 @ ENCO. *Mitutoyo is
certainly one of the top brands of precision measuring instruments in
the world.
Park has a new model out that reads out in thousandths of an inch, MM,
& fractions of an inch (which is a cool feature). I would be very
careful about its accuracy before I bought one. Some cheap Chines
Calipers are no more accurate than +- 0.007" . To me, that's not
acceptability accurate.

Yeah, you can measure it down to a thousandth - or you can just press
it in and go for it. It's a bike, not a watch or a space shuttle.- Hide quoted text -

- Show quoted text -

Yeah & you can remove the stem, the head set, the crown race, fork
after assembly if the steering binds. and then ream everything to get
the fit right. Don't ask me how I know this, having been through it
twice over the years.

0.10 mm is the correct interference. Having a fairly good caliper is
an extremely useful tool.

Actually bicycles, airplanes & aerospace craft face many of the same
problems & use similar technology from the Wright brothers onward.

The odds are probably on your side if you half ass slam any headset
into any frame. Or perhaps you won’t notice a slight bind & think it
is caused by sloppy cable routing.

There’s are right ways to do things and half assed ways, & you or any
one else has every right to chose which way. Many times the half assed
way is taken out of necessity but to knock the information for the
right way is presumptuous on your part.

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Installing threadless headset: ream head tube? Paul Conners Techniques 31 September 23rd 09 10:36 AM

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