Results 1 to 11 of 11
  1. #1
    mtbr member
    Reputation:
    Join Date
    Sep 2008
    Posts
    20

    Question about GT Marathon 3.0 seat height

    I purchased a new GT Marathon 3.0 today from Performance Bike. Based on the sale they were running, I was able to get it for $850. Based on the components that the bike has, it seems like a pretty good deal.

    I am fairly new to mountain biking and I have a question about the seat height on this bike. This may be a dumb question, but I am going to ask it anyways.

    The seat will not adjust down as far as I need it to. When I am on a bike, I am use to being able to touch both feet on the ground, while sitting on the bike. When I try to adjust the seat down, it is still too high.

    What is the normal guideline for how high your seat should be? Also, is it possible to shorten the seat post by cutting it, or do they sell shorter one?

  2. #2
    mtbr member
    Reputation: sanjuro's Avatar
    Join Date
    Sep 2004
    Posts
    1,975
    You can always cut your seatpost down. However, saddle height is based around leg extension from the pedal at the bottom of the crank rotation, not if you can touch the ground. Actually, if you can touch both feet to the ground, your saddle is not high enough.

    A simple way to get the correct leg extension is heels to pedals. With the heel of your foot on the pedal, at the bottom of the crank rotation (i.e., the pedal is closest to the ground), your leg should be almost fully extended.

    After you determine your correct leg extension, then try lowering your seatpost. Mountain bikers typically want to be able to lower their saddles about 2-4 inches for technical descents.

    If your seatpost is too high then, just lop off the difference. If you cut the seatpost too short, you could break the post or even the frame. There should always be at least 3 inches of seatpost inserted into your frame. This is referred to as Minimum Insertion.

    Finally, since you bought your bike from the experts at Performance Bikes, how tall are you are and what size bike did you get. You might have gotten the wrong size bike.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Dec 2006
    Posts
    62
    I am 5'10" tall and just got a Force and have been tweaking the fit myself coming from a hardtail myself I have the following to add.
    -on my hardtail the BB is about 5cm lower than on the Force so you need to account for that when thinking about saddle height. Don't Worry about your feet touching the ground on my best saddle setting i hardly touch the ground with the tips of my feet.

    Measuring fit by yourself is almost impossible but if you are going to get in the ballpark place you and the bike on a wall you can use to lean on, saddle height is important but also is the position of the saddle on the rails. As sanjuro said you should be able to with your leg extended with your heel over the pedal your leg should be close to straight then when your toe is over the spindle of the pedal it should be about right NOTE: this is just a good starting point! You should also be measuring the inside of your knee to the spindle of the pedal with a plumb line.

    Forget about touching the ground with your toes the most important thing is that pedaling feels good keep in mind when you have weight on the bike your toes are closer to the ground.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Sep 2008
    Posts
    20
    Thank you for your detailed reply. Your info makes perfect sense to me. Based on your description on how to adjust the seat, it is OK. The only issue is, I do not believe I can lower the seat an additional 2-4 inches.

    I feel confident that the frame size is correct for me, but I have probably been running my seat too low. I guess I just like the comfort of being able to put my foot down quickly without falling over.

    I may want to shorten the post a little bit. How do I cut the seat post? Can I just use pipe cutters?

  5. #5
    mtbr member
    Reputation:
    Join Date
    Sep 2008
    Posts
    20
    I did not consider the different height of the BB. I am coming from a hardtail (Rockhopper) and I noticed that something was different feeling. It is probably the BB height different.

    Thank you for your advice.

    I am like a kid with a new toy. This is my first full suspension bike and a bike with Disc brakes. It is too bad it is so cold here in Ohio, so I probably will not ride on a trail for a few months.

  6. #6
    mtbr member
    Reputation: sanjuro's Avatar
    Join Date
    Sep 2004
    Posts
    1,975
    Quote Originally Posted by brianr34
    I did not consider the different height of the BB. I am coming from a hardtail (Rockhopper) and I noticed that something was different feeling. It is probably the BB height different.

    Thank you for your advice.

    I am like a kid with a new toy. This is my first full suspension bike and a bike with Disc brakes. It is too bad it is so cold here in Ohio, so I probably will not ride on a trail for a few months.
    Well be careful about this. The hardtail saddle will be at the same height, whether you are sitting on the bike or not.

    When you sit on a full suspension bike, the saddle height to the floor will decrease. So if you can't touch the floor when you are sitting on the bike, then the saddle is way too high.

    I also learned this one the hard way. I had to an emergency dismount from my downhill bike, which has 8 inches of rear travel. With the saddle down, I have no problem touching the ground, but when I jumped off the pedals, the top tube slammed into my nuts!

  7. #7
    mtbr member
    Reputation:
    Join Date
    Sep 2008
    Posts
    20
    Ouch, yes I would prefer to avoid that happening.

    What is the best way to cut the seatpost?

  8. #8
    mtbr member
    Reputation:
    Join Date
    Mar 2007
    Posts
    4
    Sorry to revive this.. .I've got the same bike and I agree the lowest height setting is just right to maximize pedaling. However I want to lower the bike 2-4inches for descents, I cant shift my weight backward fast enough as the seat is in the way. Had my first crash because of this.

    Any tips on how to cut?

  9. #9
    mtbr member
    Reputation:
    Join Date
    Dec 2006
    Posts
    14
    Miter box and a hacksaw has always worked for me, and takes like a minute to do. Never had good luck with a pipe cutter, And remember if you cut your seatpost you MUST move your minimum insertion line.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Mar 2007
    Posts
    4
    Thanks! will do this this weekend.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Sep 2008
    Posts
    39
    I had the same issue, bring it into Performance.
    They'll answer all your questions & give you advice on the spot.
    They'll help you figure out a starting point for your seat height & also cut your post if needed. I had this done when I bought mine.
    So far their customer service has been top notch.
    Your correct seat height is whatever you feel comfortable.
    Base it on when you're pedaling, not when you're stopped (thats the standover height of your top tube)
    As stated, you may adjust it depending on your riding style & type of trail.
    There's no perfect set up, and as you ride more, you may feel more comfortable & want to change the height.

Posting Permissions

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