Results 1 to 4 of 4
  1. #1
    ups and downs
    Reputation: rockyuphill's Avatar
    Join Date
    Nov 2004
    Posts
    13,865

    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?

  2. #2
    LBS Manager
    Reputation: Johnny Hair Boy's Avatar
    Join Date
    Jul 2004
    Posts
    1,892

    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.

  3. #3
    mtbr member
    Reputation: GearHead's Avatar
    Join Date
    Dec 2004
    Posts
    1,008
    Quote Originally Posted by rockyuphill
    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 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.

  4. #4
    1946:2006:2066
    Reputation: FireDog46's Avatar
    Join Date
    Jan 2004
    Posts
    1,455

    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.

    Edit:

    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."

    michael
    Last edited by mrdy; 02-24-2005 at 07:23 AM.
    "Be not afraid of going slowly but only of standing still." - Chinese Proverb

Similar Threads

  1. Replies: 67
    Last Post: 03-01-2005, 06:03 AM
  2. Kona Explosif 2004 <-> 2005
    By Maixle in forum Kona
    Replies: 1
    Last Post: 11-29-2004, 02:19 PM
  3. Fisher 2004 v. 2005 geometry differences?
    By NAHTNOJ in forum 29er Bikes
    Replies: 0
    Last Post: 08-20-2004, 06:06 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •