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Discussion Starter · #1 ·
Hi all,

I am curious how these things work...I am currently on the following bike:

size - 57cm
tt - 56.5
head angle 73
seat angle 73
head tube 18.4
front center 59

I have my seat slammed to the front on a zero offset post and am barely able to get my knee to the spindle with a plumb line

I am being told the following should fit me, but I do not see how with the greater seat angle and longer TT length

size - 54.5
tt - 57.0
seat angle - 72.5
head angle - 73
reach - 39.1
head tube - 17

Does the head tube make that much of a difference? I am 5'11" with about a 33" inseam.
 

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I'd first question the accuracy of your plumb line use. Your leg proportions would have to be very far outside the norm for this to really be the case.

but no, moving the seat back via the seat tube angle won't magically move your knees forward.
 

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I agree with Jay, you should get someone to help you with the KOP measurement. With a 33" inseam, I can't see how you would have the seat all the way forward on a 57. I'm riding a 56, have 31" or so inseam and have to use a major setback seatpost.

Your seat may be too high, that will move your knee back.
 

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Discussion Starter · #4 ·
This is why I have such a headache...I had someone try to fit my current bike and said it is too big. My knees are about 1.5" too far back. Lowering the seat made me a little cramped.

I am balking at the new bike because the geometry seems off even though the dealer (who I've been told is a great fitter) says it works.

FWIW, the Two size calculators agree on a 55 frame with a 55-56 TT. Which, once again, makes me wonder why my current bike doesn't work.
 

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barely able to get my knee to the spindle with a plumb line
KOPS (knee over pedal spindle) is just a basic starting point of bike fit, not the be-all-end-all measurement. Check out this, this and this.

I'm close to your height / inseam and use 54cm frame with similar geo to the latter one in your post. I have tried KOPS method but it didn't work well because of my longish femurs. Proper fit is not an easy process and it takes time to fine tune.

Are you having problems with your current frame? If so, what are those?
 

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you're 5'11, look for a bike with an effective top tube of ~55cm or thereabout. And based on your post, it does seem like that's what you need. 57cm is too large.
 

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Discussion Starter · #7 · (Edited)
I have ever been through 4 saddles in 7 years because I ride on my perineum (and saddle nose) too much.

This winter, I focused on using my sit bones and killed my hamstrings.

Edit: heavy on the hands too
 

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I may be mis-understanding - OP has been on the same bike for 7 years and still cannot get fit correct?

Seems like something is off in the measurements. I also suspect the bike it is too big.

With that - A smaller bike is not going to change much in the way of KOPS. The seat tube angle and saddle height (distance b/t bb center and top of saddle) determine the distance the rider is behind the BB/pedal spindles. Regardless of reach/effective TT length, and the like, the seat height (distance between the bb center and saddle top) should be the same (your legs don't get longer or shorter on different size frames).

A more slack seat tube angle (new bike 72.5 vs 73 on old bike) will move OP further back relative to the BB - thus making the situation worse, not better.

I have short femurs relative to my height. I prefer steeper ST angles (74°). YMMV.
 

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Discussion Starter · #9 ·
Honestly, I'm beginning to wonder if my bike is not the reported geometry...I bought it as a closeout when I was still relatively new to cycling and don't know the official year.

This bike has been ok but never 100% comfortable, even with a few fits.

I really don't want to spend the money on a new bike, especially since I want one with an ISP (Giant Propel ) and don't feel like having a no good fit too late.
 

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Discussion Starter · #11 ·
The main re-fit that I did raised the saddle significantly. I had better power and my knees felt better, but that's when I began to feel more stretched and perineum-pained.

I flipped my stem but am still pretty heavy on my hands
 

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I, too, moved my saddle back from the KOPS position. I do have size 11 shoes, and proportionally short legs.

And I really notice the difference on slight changes to the saddle tilt.

Stack and Reach to compare bikes

I use stack and reach to compare different bikes. It determines where the bar will be placed compared to the crank axle (bottom bracket). So it's easier to see that the bars on Bike A are 2cm farther forward and 1cm lower than Bike B, for example. Most sizing charts include stack and reach along with the other measurements.

It's easy to measure your existing bike with a level and a weighted string (and a helper makes it way easier.) It's the center of the crank spindle, and the center of the head tube top.

(Seat tube angles can be a little different from each other, which positions the saddle forward or backward. But that can usually be compensated by moving the saddle on it's rails.)

 

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I think 'your' fit is all wacky. Without more details, photo's, & measurements what do you expect from the forum?
I know a guy, he swears he has higher output than the 'one' who's name can not be spoken. But gets dropped regularly on our rides. In fact he quit riding with us. He has his "story" and will not listen to anyone who tries to help him. Sound familiar?

If you get a fit, then raise the seat 2", then flip the stem, then move the seat 1" forward, guess what, you don't have the 'fit' anymore.
 

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1. Forget KOPS, it's meaningless.

2. Establish the saddle height right for you.

3. Establish reach and drop right for you. Your comment about flipping the stem on a frame that is probably too large is worrying.

4. Try a one size smaller frame. 55-56 mm ETT. Although in light of #3 I'd think an "endurance" frame.

5. Forget about an ISP frame. Not only are they a stupid idea, they are an especially stupid idea for someone playing with getting a comfortable fit.
 

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The main re-fit that I did raised the saddle significantly. I had better power and my knees felt better, but that's when I began to feel more stretched and perineum-pained.

I flipped my stem but am still pretty heavy on my hands
If a change in fit caused pain elsewhere and that pain won't go away, then that would be considered not the right fit.

Heavy on hands usually means the saddle is too far forward and or saddle tilt is too far down at the front.

It's beginning to sound like your current frame is one step too large for you, IMO.
 

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With his long legs, he should probably be on a frame one size smaller than the "standard" sizing would indicate.
 

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You're smart for being hesitant to buy a new bike until you're satisfied with your fit.

People can be pro/anti KOPS. I have no problem with either camp (I'm pro myself). If you want to fit your bike by KOPS then at least you have a baseline to compare your current fit to and it lets you know where you must change to achieve it.

I think that for your height and your description of your seat post and position, you've got something wonky going on. Backing that up is your statement about wearing out saddles, riding on your sit bones and hamstring pain, and the "heavy on the hands" statement.

I suppose you could have very short femurs or cranks that are too long. I agree that considering the alleged specs of your current bike, the specs of the proposed bike would NOT be an improvement for your fit problems. In fact, theoretically you'd want a STEEPER seat angle. Personally, I see nothing wrong with the specs of your current bike and would expect it to be an easy fit for you.

If you can't experiment with measuring your position using a trusted friend, you may have to continue to shop for a fitter that will listen to your concerns. You could try posting still photos of you on a trainer and the forum collective might get a better visual of what can be changed to help you.
 

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OP - I too am 5'11" with a 33.5 inch inseam. Further I have short femurs.

I have always ridden a 56cm frame and would not consider a 57cm as it would be too big for me. My main Bike has a 73.50 seat tube angle paired with a zero offset seat post. It is the most comfortable frame I have ever been on period - Look 585 - no longer available. My seat rails are clamped about in the middle.
I have it dialed in with KOPS - as noted this is a baseline to work with. However as an older rider I find subtle changes to have negative impact on my comfort - so KOPS it is. I have been dialed in for the better part of ten years - only changing stem lengths in that time.

All this beeing said - I believe you need to find a top flight fitter - and whatever changes are recommended do them over a period of time to let your body adjust - rather than dramatic changes all at once. Before you go to the fitter, you may want to go on wrench science or another website and plug in your measurements in the fit section just to see what they recommend - again this is not the ultimate authority, but a potential baseline. if you do this on Wrench Science, do not use the LeMond option as this is with a very slack STA - doesn't sound like that would be what you need.

As for the second recommended bike in your original post - that would fit worse than the one you have - whoever is recommending that to you is not doing you good service - maybe they do not have any 56 cm in stock. I would not trust thier judgement.

Further you should try riding a 56 cm as a comparison. When I have ridden a 57 it felt like I was towing / pulling the back wheel as it wasn't as under me as it should have been - and pushing the front for the same reason + the seat post was lower enhancing the towing / pushing issue.

The other question I would have is do you have any physical issues that would require such a long head tube on your current bike? - It would appear there is not much seat to bar drop. Or maybe the bars are higher than the seat? Further how long is your stem? These factors could contribute to your shoulder problems.

There is a lot to cover here.

Yuou can make a bike fit someone with a few compromises - Or you can buy a bike that is right sized and fits properly from the outset - the second option is always best.
 

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Discussion Starter · #20 ·
Thanks to everyone. You have all been more than helpful.

Long story short, I had a guy do a fit earlier this year and said he could not fit it without a compromise, which has always been a concern with my current bike. I really do not want to buy a new bike but do not to hurt any more.

I had 2 bikes that I liked, but talked myself into the Propel because I like the idea of the aero, like the bike shop, and it would look good for a friend. The guy is supposedly a top-flight fitter and recommended this size, but the geometry numbers bothered the OCD, A-type engineer in me. Since I know very little about bike fit, I wanted to seek advice from someone with no skin in the game.

I think I will go back to the SuperSix Evo that has a much better geometry for me (55 TT, 73.8 angle) and I liked possibly more. Who knows, maybe I will try the Gan too.
 
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