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i believe the theoretical difference is
lighter, stronger, easier to mechanicaly adjust
on the other side:
the steer tube is usually longer, which might make an upgrade
physically impossible
you must be sure the height is correct since rider adjustibleness -is
that a word?- is more limited
i have never used a threadless, so can not mkae any true comparisons
--roger
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A main advantage is that you can adjust a loose headset on
the trail with allen wrenches. Also, the headset won't loosen up
as easily as a normal threaded headset. I used to always have
problems with that - my new bike has threadless and I've only had
to tighten it once.
There is some weight savings, since the stem quill is eliminated.
Not sure how much, though.
In addition to the headset, you will probably need a fork with a
longer threadless steerer, and a new stem. If you are upgrading to
suspension forks anyways, then threadless makes sense. Otherwise,
I think I'd spend the money on other upgrades.
/ken
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I had a threaded stock fork prior to my manitou threadless. The
threaded setup used to loosen and rattle annoyingly on every other
ride or so after some good bashing.
I've had the threadless aheadset for over a year now without any
maintenance. As the previous replys had mentioned, the major advantages
were the weight savings, primarily of that of the quill bolt as well as
the easy maintenance due to it's simplicity.
I can now see why it's becoming the standard.
/todd
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re .4
How do threadless headsets work? I'll bite (you'll want to set your
DECterm 'window' options to 48, and do $SET TERM/PAGE=48 to view this):
Threaded headset
/ Internal stem (shortened for clarity)
| |
| | Steering tube (threaded)
| | /
{| |}
---{| |}--- <- threaded lock ring
---{| |}--- <-/
--| |--
| { } | <- adjustable bearing cone (threaded, screws on
\{ }/ steering tube)
[ O| |O ] <- top bearing race
| | | | <-- head tube (frame tube) with unthreaded portion of
| | | | stearing tube running through
| | | |
| | | |
| | | |
[ O| |O ] <- bottom bearing race
/| |\
| | | | <- non-adjustable bearing cone (tight fit on steering tube)
--| |--
| |
/ \ <- fork crown (side view)
As the upper bearing cone is turned clockwise, the entire fork assembly is
drawn up into the head tube, applying pre-load to the bearings (IE,
slack is removed from the fork/stearing-tube assembly). The lock ring is
then tightened against the upper bearing cone to hold the adjustment.
Threadless headset
_
| |
|-------| <--------- End plug with concentric allen-head bolt
|_______| (in threadless steering tube)
---|| * ||------\
| || * || / <- external-type, pinch-clamp stem
| |##*##| \
---| |------/
---| |--- <----- spacers (if present)
---| |--- <----- (may be moved above stem [and under end plug])
---| |---
--| |--
| { } | <- adjustable bearing cone (slides on steering tube)
\{ }/
[ O| |O ] <- top bearing race
| | | | <- head tube (frame tube)
| | | |
| | | |
| | | |
| | | |
[ O| |O ] <- bottom bearing race
/| |\
| | | | <- non-adjustable bearing cone (tight fit on steering tube)
--| |--
| |
/ \ <- fork crown (side view)
Detail of end plug (adjuster) and steering tube
_
| | <------------ Allen-head bolt
|-------| <--------- End plug with concentric allen-head bolt
|_______| (in threadless steering tube)
|| * || \
|| * || --- Overhang on plug
|##*##| <--- "star-fangled nut" with threaded Allen-head bolt
running through it (inside steering tube)
The star-fangled nut is a low-grade stamped piece with two rows of
umbrella-like wings and a threaded center - it has to be 'set' in
the steering tube so that the teeth bite into the walls of the tube
and prevent upward movement of the nut. This provides a cheap,
lightweight 'anchor point' for the adjustment bolt. To adjust, the
stem clamp-bolt (not shown) is loosened. The end-plug Allen-head bolt
is turned clockwise, pulling the fork assembly into the head tube and
preloading the bearings. The stem clamp-bolt is then tightened to
hold the adjustment. Note how the external stem is an integral part
of the threadless system. Once the stem is clamped, the end plug becomes
essentially 'functionless' - some people even remove it from the bike
and store it somewhere else (a bad idea, I think). Note that adjustment
is accomplished with one or two Allen wrenches, not a large lock-ring
wrench, adjustable wrench, etc.
Diacomp has recently come out with a more aesthetically-pleasing upgrade
for the star-fangled nut and cheesy plastic end-plug - its a machined
aluminum end cap and barrel (about 1-3/4" long) that has two concentric
Allen-head bolts (the upper one has a through-hole in it to allow a
smaller-diameter Allen wrench to reach the lower one). The lower
adjustment forces an aluminum cone up into the barrel, causing it to
expand against the inside of the steering tube - voila, an anchor point.
The upper adjustment pulls the cap (which overlaps the top of the
steering tube) into the barrel, preloading the bearings. This costs
about $25, versus $4.00 for the star-fangled nut.
Re .1:
> you must be sure the height is correct since rider adjustibleness -is
> that a word?- is more limited
Adjustments in height can be made with circular spacers - unfortunately,
some bike manufacturers cut the steering tube to precise length, leaving no
possibility of adjustment. Converting from threaded to threadless probably
implies getting a new fork (or new steering tube for a suspension fork).
If so, you'll have control over the length of the cut tube. I notice
that most Canondales equipped with threadless headsets have about 1/2"
over-length steering tubes, allowing 2 or 3 spacers, which can be configured
with various combinations above and below the stem to vary the stem heighth.
I called DiaCompe once, and they recommended a maximum of about 3/4"
additional length in the steering tube, though the rep I spoke with admitted
to running his own mountain bike with 1-1/4" extra, with no problems.
I never cared for the (low) stem height on my mountain bike (with Aheadset),
and when I added a new fork, I wanted maximum adjustability - so I went
(temporarily) for 2" inches - that turned out to involve no cutting at
all - very convenient. No problems with it so far - maybe I won't bother
cutting the tube.
Gene
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