FarHorizon

I find that when in the "3-OClock" position, my knee is a few inches in FRONT of the pedal spindle, despite having a set-back seatpost and having the seat rails mounted all the way aft. I find this VERY uncomfortable. When my leg is fully extended on a down stroke, however, I can lock my knee.

Igualmente

Well, something is wrong. What size/model of bike? What is your cycling inseam?

FarHorizon

I'll measure it today. The make/model is a Kona Unit. I'm assuming the proper way to measure is BB center to top of seat tube (minus radius of seat tube)? Is this still a valid measure for bikes with sloping top tubes?

Pants inseam is 32" so I'm guessing that floor to pelvic bone is about 33?

FarHorizon

OK - This is more comfy:



With this setback, my knee is within ¼" of being directly over the pedal spindle at the 3:00 position. The bars are still a bit too far forward now that the seat is about right, though.

My gut feeling is that this just isn't the bike for me... I've tried a half-dozen seats & posts and at least three different stem/handlebar combos. Not comfortable no way no how.

fietsbob

Free .. for Now, take bars out of stem turn stem around facing back, put bars back in.

FarHorizon

I'll give it a shot, Bob.

Igualmente

I'm trying to understand the setup a bit better. Is it correct that:

1) seated on the saddle, with your heel on the pedal and the pedal crank at 6:00, your leg is nearly straight?

2) the setback on the saddle in your photo is (just guessing based on a photo) more than 10cm or 4"?

3) that with the above, you end up almost at KOPS?

It almost seems like what you are aiming for is a beach cruiser geometry with a very low seat tube angle (like 68 to 70 degrees) which will put the saddle well back. Not really sure about that though, just a thought.

79pmooney

I have two road bikes with seatposts with much of that setback. Both bikes are completely custom. I went 74 and 75 degrees on the seatposts to 1) allow a forward position for the rea wheel so it will not slip when I am climbing out of the saddle on wet and dirty roads and 2) keep the rear wheel well anchored on descents on those same roads. But with the steep seat angles, a "big" setback seatpost will still be right at the forward limit on the seat rails. So I had 60 mm posts made for both bikes. Works out really well. (a 72.5 degree seattube and 58 cm bike frame puts a standard Campy or like seatpost right at the center of the rails. But such a seattube angle means either a poor handling bike or no room for fenders/bigger tires.

I have ridden bikes from 64 to 55 cms (used bikes with horizontal drops; if I am picky about frame size, my options get a lot more limited) and made them work with custom deep quill and very long stems. In fact the -20 degree 180 mm stem I had built for a 25" frame is now serving just as well on a 21.5" frame (sticking up a LONG ways! The quill is so long it is almost hitting the brake bolt. Safe insertion is not an issue.

My take on whether a frame fits is 1) can you stand safely over the top tube, 2) can the right weight balance be achieved over the wheels and can posts and stems be found or made to get the right fit. I bring a tape measure to any frame I am considering, get the ST, effective TT, HT, CS, WB and drop dimensions. Also the BB to TT/HT intersection. This is enough to draw up the frame. Then I know what stem will be required and the wheel locations vs the BB for weight distribution.

Now the OP here is asking in effect two questions. One about his optimum position and the other about the bike and how to accommodate that position. The OP better not take my approach and have multi $100s stem and post made to accommodate this bike to him until HE KNOWS what his body needs. $100 spent with a good, unprejudiced fitter with a Serrotta type fit bike might be money very well spent. Then he can look at his bike with a clean eye and decide the next move.

Ben

FarHorizon

Decision made. The Kona Unit is going to Craigslist pronto. I don't like the geometry, I don't like the fit, I don't like the steering.

I've put the original knobbies back on, removed the cow-horn bars for the original flat MTB ones, and reinstalled the original chainwheel and rear cog. AMF, Unit.

This was a learning experience. First, never buy a bike without an extensive test ride. Second, don't buy a bike with the intention of turning it into something it wasn't designed to be. Third, if it doesn't seem to fit, then don't buy it.

Fortunately, nothing much lost but a bit of time and a few parts (and a bit of foolish pride). A sadder and a wiser man he rose the morrow morn.

jyl

How tall, what is bike inseam?