Road Cycling - Is the seatpost too high?

My wife has very long legs and a short torso. She rides a compact frame Schwinn Fastback. But, in order to get the seat height correct, she has about 10" (25 cm) of seatpost showing. The seatpost is in the frame past the min insertion mark, so it is in fine.

The frame is compact with a decent angle on the top tube. If the top tube was straight, about 2" (5 cm) would be removed from the seatpost height.

Her riding position looks ok. In fact, when comparing the overall reach suggested on wrenchscience.com with the reach on the bike, it is almost dead on.

She says that it is comfortable. When test riding other bikes, this was the only one she felt good on. She has done several 40+ mile rides on it without any problem.

However, people keep on stopping her and saying that the bike doesn't fit her.

A custom frame is not in the cards right now. But, I agree that that would be the best solution.

Will this cause her any problems?

If her thighs hit her torso when she is pedaling, she is bent over to far, and the stem needs to come up or a stem with more angle needs to be installed. If her thighs are not hitting her torso, and she is comfortable, she should be fine. It sounds like you've checked all the parameters, she's got the correct reach-fugetabowtit.

There is no problem riding a compact frame with plenty of exposed seatpost. This is a useful way of achieveing a "custom" fit for a short bike.
Do check the layback of the saddle. For a good ballpark figure, her knees whould be vertically above the pedal spindle **when using correctly sized cranks**.
You can alter the layback of the saddle using saddle rail adjustment, then you have to swap out the seatpost for one with more or less layback of the clamp.

In the old days, seatposts came in one layback only, so custom seat-tube angles were required, but these days, ST angle is less critical.

Originally posted by MichaelW
There is no problem riding a compact frame with plenty of exposed seatpost. This is a useful way of achieveing a "custom" fit for a short bike.
Do check the layback of the saddle. For a good ballpark figure, her knees whould be vertically above the pedal spindle **when using correctly sized cranks**.
You can alter the layback of the saddle using saddle rail adjustment, then you have to swap out the seatpost for one with more or less layback of the clamp.

In the old days, seatposts came in one layback only, so custom seat-tube angles were required, but these days, ST angle is less critical.

KOPS is not an ideal way of checking if the bike fits since it onlyholds true if you're on a flat road.
Reach and leg extension are the most crucial dimentions, followed by seat tube angle
If shes comfortable and her knees don't knock her elbows when riding on the drops then she sounds like she has a close to ideal fitting bike.

Also if the bike's dimentions measure up to Wrenchscience's fitting system then the bik is probably perfect. Their system is well sorted.
You can also verify that by using <http://www.bioracer.com> and a few others. Each will give you slightly different dimentions but statistically they all give you the same answer

"Knee Over Pedal Spindle" (KOPS) is not ideal, but it is the best there is. If the rider wants to ride forward or back from that position, that is a personal choice, but KOPS provides a measurable starting point.
If you look at manufacturers geometry tables, smaller frames are built with steeper seat-tube angles. Riding a small frame with a highly extended post will result in a more forward saddle position than a larger frame with shorter post extension.
Personally, I think that smaller frames are steep to allow KOPS with proportionally long cranks, which is an odd way to design a bike.

All this technical discussion aside, you can setup the points of contact (pedals, saddle, bars) to be in a comfortable position, on a variety of different sized frames.

All this technical discussion aside, you can setup the points of contact (pedals, saddle, bars) to be in a comfortable position, on a variety of different sized frames.

exactly hence the reason I say it shoud'nt be used for sizing. KOPS should be the last thin you look at.
Reach and frame size first. then find the ideal position for your pedalling style.

I set up my Litespeed in reverse ie ignoring KOPS and came out with my knee ahead of the axle (high cadence suits me).
The longer front centre gave me a greater variety of positonal choice.

Thats the only reason say Don't use it. It is a useful check but the set up shold not be determined by it.


Comfort first ie reach and frame size and set up from there to maximise power.

Originally posted by TimB
exactly hence the reason I say it shoud'nt be used for sizing.

I think of KOPS as a filter -- a proof that a frame doesn't fit, rather than a sure indication that it does.

If you can't achieve KOPS without going to extremes -- changing the seatpost to add or remove a great deal of setpack, moving the saddle all the way forward or back, etc. -- then you should avoid that frame, IMO.

I also think that KOPS should be the setup normally used when determining whether the top tube is of correct length.

You may not ride the bike that way, but if you can find a frame and crankset combo that puts you at KOPS with the saddle centered fore/aft on the rails, and the reach is good with an average (110, 120) stem, then you may have found the perfect frame. It will allow you to adjust your reach or your saddle position without seriously affecting the performance of the bike.

RichC

good points RichC If used as a filter I would agree that is still has a place in sizing.
A proper bike fit tool like wrenchscience has, should be still be the starting point though