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 was climbing out of the saddle, I was analyzing my technique. I learned a long time ago that you let the bike move and you keep your body steady. That way there is little force on the stem and bars to make them deflect.
~mike On May 7, 2:06 pm, Ken Freeman <kenfreeman...@gmail.com> wrote: > DDDDOOOOOHH! I knew that, once upon a time! > > Cheers, back! > > > > > > On Saturday, May 7, 2011, James Valiensi <valie...@mac.com> wrote: > > Actual, the polar moment of inertia is to the 4th power: > > PI()(D^4-d^4)/32.Cheers! > > > James Valiensi, PENorthridge, CAH818.775.1847 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, 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 back of an envelope, and no finite element work!! > > > On Sat, May 7, 2011 at 1:15 AM, James Valiensi <valie...@mac.com> wrote: > > 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. > > The extension into the fork vs. clamping on the outside of the fork are not > > significant here. > > By the way, neither stem deflects that much. > > If you really want a stiff stem, use a short extension, and big diameter. > > And steel too. > > And you know why they went to 31.8mm diameter handle bars? Because of the > > stinking cable grooves. The grooves make the bar section too flexible, the > > bigger diameter overcame this. > > Cheers! > > James Valiensi, PE > > Northridge, CA > > H818.775.1847 M.818.585.1796 > > > On May 6, 2011, at 6:44 PM, Philip Williamson wrote: > > >> 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 May 6, 9:24 am, "Bill M." <bmenn...@comcast.net> wrote: > >>> 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 of the bike felt. The quill stem was allowing > >>> the bars to twist, the new one wasn't. > > >>> That may or may not be seen as a good thing, but I have no doubt that > >>> typical threadless stems are stiffer in torsion than traditional quill > >>> stems. > > >>> Bill > > >>> On May 6, 3:58 am, MichaelH <mhech...@gmail.com> wrote: > > >>>> The new RR contains an article by GP outlining his believes about > >>>> various aspects of bike strength, comfort, weight, and comfort. > >>>> There wasn't much new there for anyone who has followed him for a few > >>>> years, including why he prefers threaded headsets and stems, but it > >>>> did trigger this question from me. > > >>>> My son, who is 39 years old and a very muscular 170 lbs claims that > >>>> he experiences stem flex while climbing with a traditional quill > >>>> stem. I am always disinclined to challenge people's subjective > >>>> experience but I have never experienced this and suspect it is in his > >>>> imagination. > > >>>> Has anyone here felt their stem flex and has anyone ever broken a > >>>> stem? > > >>>> michael > > >> -- > >> You received this message because you are subscribed to the Google Groups > >> "RBW Owners Bunch" group. > >> To post to this group, send email to rbw-owners-bunch@googlegroups.com. > >> To unsubscribe from this group, send email to > >> rbw-owners-bunch+unsubscr...@googlegroups.com. > >> For more options, visit this group > >> athttp://groups.google.com/group/rbw-owners-bunch?hl=en. > > > -- > > You received this message because you are subscribed to the Google Groups > > "RBW Owners Bunch" group. > > To post to this group, send email to > > > -- > > You received this message because you are subscribed to the Google Groups > > "RBW Owners Bunch" group. > > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > > To unsubscribe from this group, send email to > > rbw-owners-bunch+unsubscr...@googlegroups.com. > > For more options, visit this group > > athttp://groups.google.com/group/rbw-owners-bunch?hl=en. > > > -- > > You received this message because you are subscribed to the Google Groups > > "RBW Owners Bunch" group. > > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > > To unsubscribe from this group, send email to > > rbw-owners-bunch+unsubscr...@googlegroups.com. > > For more options, visit this group > > athttp://groups.google.com/group/rbw-owners-bunch?hl=en. > > -- > Ken Freeman > Ann Arbor, MI USA- Hide quoted text - > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. 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