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Stem and Headset Questions(12 posts)

Stem and Headset QuestionsFez
Feb 26, 2003 7:29 AM
Does anyone make a threadless headset with a very tall stack height? If so, would this provide more support to the steerer tube in lieu of spacers? In theory, wouldn't a taller headset also offer more insulation from dust for the bearings, at minimal extra weight?

And from an engineering standpoint, is there an optimal stem angle for responsive steering and stability? -17, -10, -6, 0, +6, +10? Assume that the taller or shorter steer tube necessary for each respective stem angle is not a factor.

Snow is coming so I'm bummed I can't ride...
re: Stem and Headset QuestionsRusty Coggs
Feb 26, 2003 7:51 AM
I think you are grasping.Boredon bites doesn't it?
re: Stem and Headset QuestionsFez
Feb 26, 2003 8:00 AM
do you have snow?

looks like another evening at home with the wife watching meg ryan movies.
Rent 'Something Wild'. Nice 8oobs. ;-p nmSpunout
Feb 26, 2003 8:15 AM
Head tubeMR_GRUMPY
Feb 26, 2003 8:28 AM
A frame with an extended head tube would solve your problem.
Head tubeFez
Feb 26, 2003 8:45 AM
For a new frame, yes.

But not for an existing frame with a shorter headtube.
Colnagotarwheel
Feb 26, 2003 9:29 AM
Colnago makes a very nice looking threadless headset with a relatively high tall stack height, 43 mm. That's still not much though. Short of ordering a custom frame with an extended headtube (or buying one of the few stock frames that include them), you can buy a Serotta ti headtube extender for about $60. I think it adds 2 cm to the headtube, and fits below the upper portion of the headset.
Serottatarwheel
Feb 26, 2003 9:31 AM
Here's a photo of the Serotta "Heads Up" extender. It's 2 cm high.
Cool, so the cup fits on top? Need new forks now :-( nmSpunout
Feb 26, 2003 9:55 AM
stem anglestarwheel
Feb 26, 2003 9:38 AM
I've used threaded and threadless stems with angles varying from the traditional -17 to +15. I can detect no apparent change in handling, with regard to the handling (all things else being equal). However, as you increase the rise, you also need to increase the stem length to maintain the same reach. The length (or reach) of a stem can affect handling quite a bit, though. A shorter reach stem will steer much quicker and might seem twitchy. A longer stem provides more stable handling and slower steering. This is very noticeable if you've ever swapped for a longer or shorter stem.
stem anglesFez
Feb 26, 2003 12:11 PM
Good point about the stem length.

But if you do the trigonometry, over a 32 degree span (-17 through +15 degrees), the extension should only be changed approx 1.5cm to maintain the same effective reach.

Most stem angle changes are less drastic (for example, going from -10 to zero), thus the max stem length change would be 1cm or less to maintain the same reach. That's probably not enough to change handling characteristics dramatically.
don't agree...C-40
Feb 27, 2003 5:54 AM
A change in stem length should not make a significant difference in the steering response. The length of importance is the "steering arm" which is the distance from the brake hood (or other point of hand contact) to the center of the steering tube. This distance is around 12 inches. Changing the stem length from 8 to 12cm only changes the length of the steering arm by about 10%. Although it's noticeable at first, the difference will not be noticed after the first ride.

Stem angle should have no effect at all on the steering response.