When we tested bikes for heavy front loads, we found that the flex of
a quill stem did cause some trouble. There was a slight lag of the
fork after the steering input. This was with 30 lbs. on a porteur
rack... In normal riding, even with fully loaded front low-rider
panniers (which are much closer
I was out riding today and thinking about this issue. Now today I
had the lugged Nitto steel stem on my Rando bike , about 7cm of quill
showing. If there is some flex, I sure can't tell. But, similarly on
the Ram with a Nitto Pearl and about 6cm to center of stem there was
still Nothing. As I wa
With carbon fiber, all the old standards are thrown out!
James Valiensi, PE
Northridge, CA
H818.775.1847 M.818.585.1796
On May 7, 2011, at 7:01 AM, Bill M. wrote:
> I suspect that the introduction of carbon fiber bars had something to
> do with the introduction of 31.8 mm bars as well.
>
> Bil
I suspect that the introduction of carbon fiber bars had something to
do with the introduction of 31.8 mm bars as well.
Bill
On May 6, 10:15 pm, James Valiensi wrote:
> Hey,
> My back of the envelope calc's indicate a standard aluminum quill stem will
> deflect about ten times more than a stee
Actual, the polar moment of inertia is to the 4th power: PI()(D^4-d^4)/32.
Cheers!
James Valiensi, PE
Northridge, CA
H818.775.1847 M.818.585.1796
On May 7, 2011, at 5:29 AM, Ken Freeman wrote:
> Ok, so the steel stem has a larger OD AND a stiffer modulus. Staying on the
> back of an envelope,
Ok, so the steel stem has a larger OD AND a stiffer modulus. Staying on the
back of an envelope, the ratio of 31.6^2 to 22.2^2 is about 2. In which
case your calc requires the ratio of moduli to be about 5. For steel it's
about 30,000 ksi and for aluminum it's about 10,000 ksi.
Not bad, for the
Hey,
My back of the envelope calc's indicate a standard aluminum quill stem will
deflect about ten times more than a steel stem. This is with equal extensions
lengths and loads, and the aluminum stem has a solid 22.2mm diameter extension,
and the steel stem is 31.8mm OD w/ 25.4mm ID extension. T
When I got my Quickbeam, I tried a couple of stems, including the
stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably
more than the Salsa welded stem I ended up with. The Dirt Drop not as
much as the Technomic Deluxe, but the quill was bottomed out in the
steerer.
Philip
On M
On May 6, 7:24 am, "Bill M." wrote:
> The quill stem was allowing
> the bars to twist, the new one wasn't.
That's my experience, too. I have 12 bikes and only 2 of them have
clamp-on stems. When I ride those two bikes, I'm always struck by how
much the stem doesn't twist (ie.: is torsionall
I use Noodles on 3 bikes with 3 different stems. The flex
characteristics out on the hoods is different for all three. The Tech
DLX 11cm extension feels the flexiest. It feels a lot less flexy now
that I have it about 3/4" below min insertion. The Nitto Pearl 11 is
less flexy still, which I att
Mike,
I can say without question that it is my Tech Delux that moves around
under torque loads. I have the same RM013 bars on bikes with both
different styles of stems. On my Rawland with the threadless setup you
can feel the spring in the drops rotating primarily around the about
the same axis as
Is he he sure it's the stem that's moving? Based on the forces that
are applied rididng out of the saddle and the different cross
sectional areas, I would think that the bar is what's moving the most.
Both move some amount. I've never usd the taller Nitto Technomic stems
( if that's what your son
Back in 1991 I bought a Cannondale (very stiff frame) that came with a
standard quill stem. I swapped it out for a hollow, welded stem that
had a much larger diameter extension. The first time I stood up and
cranked the bike up a short steep rise I was astonished at how much
stiffer the front end
Definitely. I weigh 245 and raise my stem to the max insertion line
(never beyond). And this is with the Nitto Dirt Drop; not a flimsy
cheap stem.
And, since I believe Nitto tests the hell out of their products, the
fact that my stem flexes a little sometimes doesn't bother me in the
slightest. (I
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