Music!

I watched and read anything I could on seatpost height (saddle height), but have a tiny question that might come simple to 90% of you.
I have my seatpost set up so that my leg is 90% extended (I know that, that is recommended), but, here's where my problem is. At the lowest point of the pedal cycle, should my foot by parallel to the floor, or should the ball of my foot be lower or higher?

Side note: I have a Panasonic dx-4000 stock with a SR Laprade seat post. It comes numbered. At "optimal height" for myself, it is at 1. That's near the base of the seatpost. It has approximately two and a half inches in the frame, and 4.5 to 5 inches outside the frame. With that seatpost am I lingering on a catastrophe?

Panthers007

Standing on your heel, the pedal should be at the bottom of the crank. Adjust the seat to this. Then as you pedal (on the balls of your feet) - there should be a small bend in your knees at the bottom of the stroke.

DaveSSS 

Here's a common starting point. Set the saddle height so the foot is horizontal with the leg fully extended at the bottom of the stroke. During normal pedaling, most people pedal with a 2-3cm rise of the heel. This heel rise creates the commonly recommended 30 degree bend at the knee at the bottom of the stroke. The knee should not be almost fully extended during normal pedaling. It should have a significant bend.

If you don't raise the heel, then the saddle would need to be lower. There's no right and wrong to heel rise, but no reason to intentionally drop the heel at any point. This had been proven by studies of trained cyclists. Ankling is a waste of energy. You won't see Alberto Contador dropping his heel as he climbs to win the TDF.

Music!

Thanks to all who replied. I took a picture of myself while on the saddle to check my own form from the size. To my shock, my knees are incredibly bent. 0_0 Wth? I felt I had reached the best saddle height and didn't realize that my legs were that bent. Now the problem lies in my second question. With said seat post with only two inches left in the frame, is it even safe to go up another few cm? I mean, should I just buy a new seat post, or will this SR Laprade seat post fare well with only 1.5 in inside the frame?
Thanks again.

davidad

Look at your pedeling style late in a hard ride. You will find out how your foot naturally falls. If you pedal toe down then raise the saddle a little to compensate.
I use the 89% of leg length that I read about 15 years ago in Lemond's book. 89% of leg length measured from the center of the BB to the top of the saddle along the seat tube.

daveizdum

Is there a minimum insertion point on the seat post? Look for some markings.

Music!

Yeah, actually, about two cm below my current setup there is yet another line, but it is incredibly sketchy how close it is to the end of the post. Should I quit my arrogance and assume the manufacturers knew wth they were on about when they marked it?

daveizdum

If this is the post that came with the bike, I'd trust the manufacturer. If you're nervous, there are plenty of seat posts that aren't expensive. A longer one would also give you the opportunity to raise the post in the future, if you decide that it needed it. A cheap new one would be <$20.

Music!

Thanks a lot. I really do feel uneasy about that seat post holding onto nothing but the desire to keep it in. I will buy another seatpost at an lbs with about two to four inches added in length, my seat post - upon further analysis - is about an inch too low (yikes). Is there any sub $20 you would recommend, really it's no biggie, but you might have a favorite.

joejack951

If the line seems really close to the end of the post, it's very possible that the seatpost has been previously cut to reduce weight. Seatposts generally have the line at least a few inches from the end of the post. I would not use a post that was only inserted an inch into the frame.

neil0502

Old rule of thumb: no more than about a handful of seatpost showing.

Doesn't work so well on frames with compact geometry, but ... holds up fairly well .... generally.

operator

Fitting over the internet is like trying shoes on over the internet.

Teemu Kalvas

If you don't know whether someone's cut the post at some time, you should not have insertion less than 2.7 times the diameter of the post. Also, the bottom of the post must always be below the top tube joint, irrespective of any post markings and post manufacturer advice, otherwise you'll be risking the frame.

DaveSSS 

The absolute minimum is 5cm or the post should at least extend slightly below the bottom edge of the top tube.

FBinNY 

Definitely, you need a longer seat post. At only 1-1/2 inches of insertion it fails both critical tests for determining minimum insertion.

1- it should exceed 2 diameters of the post, (ie. 2x 27.2 + 54.4mm) so the post is wellsupported in the tube and won't cam out, or overly stress the seat tube's thin walls.

2- it should extend below the bottom of the top tube by at least 1" so it supports rather than stresses the frame down to and beyond the top tube/seat tube joint. This is an important consideration when seat tubes extend beyond the top tube, since the minimum insertion mark on the post may be inappropriate to this application.

Music!

Thanks to all who replied! It is decided I need a new seat post.

Music!

Wait, one last question, fbinny, you said that it would mess up my frame. I used the bike in that state about 4 times. How much damage did I do?

Music!

New info. The max seat height is 268, mm? Measured from where? Top of the saddle or the metal for the seat post?
Thanks!

FBinNY 

Unless you're fairly heavy, I doubt anything happened yet, but imagine what might have, if the post were pushed back. Look for dents or ripples in back of the post where it met the frame, and a bulge in the front of the seat tube lined up with where the bottom of the post was.

26.8mm is probably the diameter of the post and just happened to be written below the minimum insertion mark. Usually manufacturers print all the info just below that mark so it won't show when the post is used. Like I posted earlier, that line represents the minimum from the seat post makers point of view, but may be too little for certain frame designs.

Music!

All correct fb, that is the size. I found one on JensonUSA, because my lbs doesn't carry any 26.8s.
At JensonUSA it's $16 link: https://www.jensonusa.com/store/produ...+Seatpost.aspx

Also, I assume 350mm would be the sweet spot, but I have three numbered questions:
1. Is that seatpost worth it? (any equal or lower price better options?)
2. How much seatpost should be inside the frame (percentage of frame)?
3. Where the I measure the seatpost from, the top of the clamp or the bottom of the clamp? (it is pivotal)

Thanks, this is all really informative.

Panthers007

If a 350mm seatpost is too short - you need a larger frame. $16 is quite inexpensive for any new seatpost. My Thomson seatpost runs around $80.

Don't forget to slather the post with grease, and smear some grease into the seat-tube as well. Your future-self will thanks you.

Music!

350mm is too short? I only need about 2 more cms. Also, the frame is not too small, it's the best fitting frame I've had in a while. Could you please elaborate on how 350mm is too short.
I will grease; that's good advice.

Panthers007

The operative word is "If" - not "Is."

Music!

Haha, panthers! I must sleep earlier. Agreed.
300mm might do just as well, but maybe the extra 50mm will add more support to my frame.. Sketchy reasoning.
Again, thanks.

Panthers007

You can always shorten a seatpost. But you can't lengthen one. Unless you're insane and have a TIG Welder.