effects of the position of the seat, offset...

[faded1004]

hey, i was just wondering what was the main effects were for seat position in terms of offset.

logically, i would think that moving the seat will move the balance of the bike to the rear... not good for climbs if i am correct. and downhill you have to stay above and behind teh seat right?

so does 10mm-25mm make a huge difference? if i lean forward normally and stay off the seat on downhill, does that mean the offset won't make a big deal?

the reason for this offset question is because i am thinking about swaping out my seat post and put in something to lengthen the distance from bar to seat... mainly for comfort riding with GF.

so let me know what you think...

thanks!

[Zippy]

The position of your seat is only relevant when you're sitting on it. When you're standing on the pedals, what matters is the position of your center of gravity relative the the center of the bicycle. Get whatever seat post feels right to you.

Don't forget: raising your seat will require you to move it forward since a seat post is angled. Lowering it will require you to move it back to maintain the same set-handlebar ratio.

You may also wish to mark or measure where you have everything set currently to give you a reference point for making adjustments.

Good luck!

[genusmtbkr5]

No need to get an offset seat post unless you feel that you want distance away from your cockpit and you already slid your seat back. When you are in your riding position, typically your bars should be lined up with your front axle when you look down and you're seated comfortably on your seat. It wouldn't be a bad idea to get a fitting done so you don't start getting back aches or knee problems when riding a long time. Another thing to consider is you won't be able to lower the seat as much because of the offset.

[faded1004]

okay, so what i was thinking was right... not a big deal as most of the time you aren't really on the seat... unless you are just cruising...

gene, i will have to check that handle bar sight measurement... i never lookd at that...

interms of what i have already... i think it is good. i have the seat all the way back on the rails already and that is why i wanted to try out alittle offset to see how it feels. so far, i got the perfect height for the post, so now it is off to check out offset and also maybe do alittle more work on actual seats too...

edit:

okay, looks like there are alot of things to worry about in terms of fitting... man, i dont even think i thought about 80 percent of these things when building a bike! here is a quick link incase anyone is wondering the same things in terms of fitting to a bike...

http://www.rei.com/learn/Cycling/rei/learn/cycle/clfitf

i am going to have to ride tomorrow and take pics of my posture... i will try to post it and get som feed back incase there is something really bad that i can't see...

[RS VR6]

I recently used the kneecap-over-the-pedal spindle measurement for my saddle fore/aft...and my butt feels alot better. Turns out that my saddle was too far back.

[Pho'dUp]

faded, there's a ton info. on fit. too many variables to get into especially since everyone's body, bike, and riding style are different. Even the knee over spindle is just a general guide.

just a tip. Keep a notebook of your bike(s). what parts are on it, and measure as many things as you can before you start making changes. i.e. handle bar height, cockpit length, saddle height, saddle position fore/aft, etc.

this will also help you when you build a new bike. you can get it dialed really fast than just guessing at how to set things up.

[Nagaredama]

The whole bike fitting thing is based on road bikes. Typically riding on the road you're in the same position for long amounts of time. When riding on dirt your position on the bike is very dynamic to deal with turns, rocks, drops, and the rest of the terrain.

Find a comfortable saddle position and rock it.

Lee McCormacks randoms thoughts on things like cockit length and saddle height.

http://www.leelikesbikes.com/cockpit...aapablity.html

http://www.leelikesbikes.com/seat-he...-maverick.html

[2wheel_lee]

Originally Posted by RS VR6

I recently used the kneecap-over-the-pedal spindle measurement for my saddle fore/aft...and my butt feels alot better. Turns out that my saddle was too far back.

Hopefully you meant the bone just below the kneecap. This is really the best way to set up the fore/aft seat positioning. Having the seat even 10 mm too far rearward does greatly affect your efficiency. Unfortunately, I see a lot of people who have their seats way to far rearward to try and make up for a overly short cockpit. I think that's a big mistake. You're much better off having a short cockpit than to have your seat too far rearward. As RSVR6 said, your butt and your legs will thank you.

Seat height can be within about an inch of range (depending on the person's height), and it'll be ideal. This is a matter of comfort (recommended knee bend angle is about 25-35 degrees, which is what translates to about 1" of seat height for me). Remember, as the seat goes up, it also goes rearward, so you have to remember to adjust it accordingly.

[RS VR6]

At first it was the kneecap...then according to MBA...the center of the kneecap...then lastly I read the bump below the knee.

I don't know if it was in my head...but on my first "steep" climb of the day...felt alot easier to pedal...

I made my own pendulum measuring thing, by tying a long piece of string to a nut.

[jeffj]

Adjusting the saddle position is the first thing to get right, then all the cockpit fit issues can be addressed. Moving the saddle fore and aft affects all the cockpit adjustments.

I just use cheap stems until I get the saddle position sorted out and then use the various stems to find the right bar position before investing in a good stem of the right size.

If it's easier to do so, you can measure from the kneecap and plumb to the front of the crankarm instead of the C/L of the pedal axle.