To reiterate a previous post, one has to wonder what Rocky Mountain was smoking when they
spec’d these bikes. The 2002’s and 2003’s came with a 100 mm fork and the geometry sheet
listed the head angle as 71 degrees. The 2004’s come with a 125 mm fork and the geometry
sheet lists the head angle as 70.5 degrees.
The math doesn’t add up. A 125 mm fork should slacken the head angle by 1.2 degrees.
Using high resolution digital images and a vector drawing program, these are my conclusions.
Regardless of which fork is used, the head angle is .7 degrees steeper in the 4.5” travel setting.
The 2002/03 listed head angle is for the 3.5”/4.0” travel settings. The head angle steepens to
71.7 degrees in the 4.5” travel setting. The 2004 listed head angle is for the 4.5” travel setting
and slackens to 69.8 degrees in the 3.5”/4.0” travel settings.
With judicious use of rear and front sag one can balance the bike and compensate for the change
in head angles. One recommendation I have heard ( not mentioned by any LBS I know of ) is to
adjust the rear and front sag levels in the 4.0” travel setting. When you move to the 4.5” travel
setting, the increased leverage ratio will increase the rear sag, compensating for the increased
This is what I found myself doing intuitively when I first got mine. I was running about 30% sag
in the rear and about 10% in the front. And never had a problem with handling in the 4.5” setting.
It was when I converted to coil that the head angle discrepancies came to light. You can’t bleed
a coil to get the right sag. I am waiting on a new set of springs for the rear since the 600# one
I have now is too heavy for the 4.0” setting and could be just a touch softer for the 4.5” setting.
To those considering an ETSX, don’t be put off by this information. The ETSX is one hell of a fine
bike. I had been riding a GT LTS2 since 1996 and after a few years I started looking for a new
bike…and kept going back to the GT. Nothing a tried was better. Then in 2002 I rode an ETSX.
That was it. Bought it the next day. Have never looked back or at another bike.
Does anyone know where I could get a hex bolt to replace that damn shock QR?
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Thread: RM ETSX Head Angles Explained…