ETSX 2004 to 2005 geometry change?
Checking out the geometry differences between the 2004 and 2005 ETSX 70 frames, there's two major differences. The '04 has a BB drop of 13mm and the '05 has a BB drop of 23mm. The standover height on the '04 19" frame is 798mm and the standover on the 05 is 808mm.
Assuming they are both measured at the same travel settings, the 23mm BB drop should translate to 10mm less BB clearance as it's 10mm further below the axle height, but it also seems to result in 10mm higher top tube which would seem to indicate the frame is taller through the rider cockpit.
The new TALAS has 5mm more travel, but that wouldn't result in 10mm more top tube height unless it also has more crown to axle height beyond the increased travel.
Does anyone have an insight into these geometry differences?
I think its the travel setting
My 05 has the same feel and stand over high as my 02 did so the only gues I have is they must have measured in two diferent rear travel setings.
I am not sure where RM gets their geometry from, neither the '04 or '05 have BB drop unless you were to put the bike at minimum suspension travel. I have an '05 with a BB height of 13-3/8" at full travel and probably a BB drop of about 1/2" at minimum travel. The 808 mm standover sounds about right for a 19" frame '04 or '05.
Originally Posted by rockyuphill
definitely the travel setting...
Across all model years the BB drop increases 10mm moving from the 4.0/3.5 to the 4.5
travel setting. This increased the head angle by about .5 degrees with the bike unladened.
However if you set sag at the 4.0 setting, then moved to the 4.5 setting, the head angle
would more or less stay the same when mounted since sag would increase compensating
for the increased static head angle.
Further complicating the issue is the different forks spec'd by RM.
Marzocchi 100mm @ 10% - 20% sag: HA = 70.0 deg
Fox 100mm @ 10% - 20% sag: HA = 70.0 deg
Fox 125mm @ 25% - 35% sag: HA = 70.5 deg
Fox 130mm @ 25% - 35% sag: HA = 70.5 deg
The Fox 2005 130mm has beefed up lowers and probably adds 5mm to the over all length.
Add in the increased travel of 5mm you have a fork about 10mm taller decreasing the HA
by .5 deg back to 70.0
To maintain the 70.5 deg HA for 2005 they have to be using the 4.5 travel setting.
According to RM all catalogue geometry spec's are at proper sag front and rear.
Pity they don't post what rear travel setting and sag levels in mm for the front and rear shocks.
Would end all this confusion.
'Cause, though I may sound like I know what I'm talking about, I'm still not sure.
Here are some comments from my RM engineering source, dated April 15, 2004.
"The numbers shown in the catalogue are from the computer models used to
generate the frame drawings. Because our geometry is based around the bike
being at ride height (that is, both front and rear suspension at proper sag
levels), it is very difficult to correlate these numbers to what the bike
measures up at statically. This is further complicated by the fact that the
bike's geometry is dynamic in nature, depending on the relative position of
each wheel in its range of motion. For example, the bike's actual geometry
with the fork fully compressed and the shock fully rigid would be much
steeper than the catalogue geometry; conversely the actual geometry would be
much slacker with the fork rigid and the shock fully compressed.
It is true that the geometry of the platform as a whole changes between the
different travel settings. This was an unfortunate by-product of the link
plate design and the platform designer (not me) either did not consider that
the geometry would change or thought the amount of change would be
insignificant. It has been noticed, but not to a large extent - I believe
this is because most people do not change the travel setting frequently.
Most people could probably feel the difference of a 1-degree head angle
change, but I believe it takes a pretty discriminating rider to note a
difference of less than one degree (e.g. 0.5 degrees). I do not have an
ETSX bike around right now to do these measurements, but if I run across one
in the next little while I will endeavour to get the numbers for you.
As for the travel setting, the default setting we use on the computer model
is the 4" position."
Last edited by mrdy; 02-24-2005 at 07:23 AM.
"Be not afraid of going slowly but only of standing still." - Chinese Proverb
Last Post: 03-01-2005, 06:03 AM
Last Post: 11-29-2004, 02:19 PM
By NAHTNOJ in forum 29er Bikes
Last Post: 08-20-2004, 06:06 PM