With the below measurements, would size S be suitable for Lynskey Cooper CX -

Inseam 75cm
Trunk 68.5cm
Arm 63cm
Height 178 cm

Intended use - commuting, touring, group ride, general purpose riding

Simple question, but not an simple answer. First, do you know for sure that a Lynskey would fit you well? Second, here's the "problem" with the question, body measurements are quite poor indicators of bike fit. Other factors internal factors would be flexibility, core strength, current/previous injuries/issues, type of rider. Then add the external factors (which you did touch upon), distances and types of riding/racing, terrain, etc. etc. etc. etc.

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"Suddenly the thought struck me; my floor is someone elses ceiling" - Nils Ferlin

i prefer the CX for the following reasons -

1) titanium - durability, ride quality, nice finish, ...
2) rack mount - touring
3) fender mount - fender mount
3) disc brake mount - riding in rain and less maintenance required as compared to cantilever
4) tire clearance - wider tires would be more suitable for my intended use
5) availability - one of the few established titanium frame-makers that LBS in my country are dealing
6) budget - consider all above, it is more affordable than Moots, Firefly etc

The Sportive would also match all except tire clearance (28mm to 34mm).

The LBS don't have any bike to try on...

Are there any simple methods which i can determine my flexibility, core strength etc?

That inseam seems exceptionally short for your height. Posting your actual saddle height would be beneficial. I would expect a saddle height of around 65cm with that inseam. If you saddle height is a lot more, then you've mismeasured your inseam.

I'm just the opposite, 9cm shorter, with an 83cm cycling inseam and 73cm saddle height.

The size S is probably the only one with enough reach for your very long torso, but the standover height is greater than the inseam that you posted. That could make for some uncomfortable situations.

Even with my much longer legs, I'd buy the XS.

If you know the TT length and seat tube angle of your current frame, what stem length are you using with it? It should be easy to make a comparison.

http://www.lynskeyperformance.com/store/cooper-cx.html

You are right, the saddle height is about 68cm

The effective TT is 56cm, STA is 74 degs. i am using a very short stem of 60mm.

My current bike size is definitely wrong. The seat tube length c-t is 58cm, and standover height is 83cm. I experience aches at the back of my heel.

That's why i am more cautious to get a proper sizing

You are a similar morphology to a friend of mine - but even longer torso and shorter legs.

Looking at the Lynskey Geometry, you would probably fit on a small or a medium seeing as there is only one CM difference in the TT. There is a two CM difference in the HT though so you really would ideally try both before deciding.

If that's simply not possible, I'd probably go for the small as you'll have more standover height.

You may need a number of headset spacers though depending on your preferred riding position.

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Not everything that counts can be counted. Not everything that can be counted counts.

i assumed you consider ETT as most important figure for frame size. If so, i agree with that since there is less allowance with saddle setback and stem length.

How does HT length affects fit, comfort and efficiency?

Head tub elength will not be a problem. This frames uses a conventional press-fit headset that will have a stack height of 25-30mm. Spacers could always be added, but with such a short saddle height, there will not be any problem with saddle to bar drop.

The bigger issue is how you arrived at a 60mm stem length with a 56cm TT. Have you ever had a professional fitting? With your long torso, I'd expect a much longer stem.

Either the XS or the size S would allow a longer stem to be used. Since the STAs are so similar, any reduction in The TT, would add the same amount to the stem length.

Thanks for spending time to explain that


Eh...no. It was a mistake
Can you clarify on how i can calculate the proper ETT?

There really is no way to calculate the TT length that you need. Stem length would go a long way toward getting the reach that you need.

As I noted, the size S frame has all the standover height that you can tolerate and only has a 54cm TT length. Even with my very short torso, I use a 53cm TT, with a 110mm stem, but I do use short reach bars. If I had normal reach bars, I'd use a 100mm stem. I would expect you could use a 54cm TT and at least a 120mm stem with standard or even some long reach bars. Standard reach bars are around 85-87mm, measured c-c. There are a few brands with more reach, but you have to be careful to properly understand how the reach is measured.

Get a fitting - this isn't a question for an Internet forum.

Despite the previous poster's comments, I will respond to your questions. Yes, I always size bikes off the top tube as first order of priority because in my experience, if the bike is too long or short there, it will never fit properly. I'd always aim to achieve a TT that is comfortable with between a ten and twelve stem. After that, I look at standover and head tube - really looking for a balance of aesthetics and fit. Then I look at geometry to be sure there are no weird angles of other aspects that will affect handling. I'd be looking for all of those boxes to be ticked and would rule a bike out if it was wrong on any of those major categories. Even if you can't ride a Lynskey in advance, try a few bikes at your LBS that have similar dimensions and see how you fit as that will give you a very and I stress very - rough guide. I hope that helps.

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Not everything that counts can be counted. Not everything that can be counted counts.

Thanks for the valuable suggestion and advice. There's no doubt that top-notch professional fitting will yield the best result. Before i decide to go that direction, it is beneficial to gain a better understanding of the logical and scientific methods people are using. "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime."

Wow and here I thought I was the only truly short legged cyclist, always envied everyone and their nice saddle to bar drop...

Your measurements look pretty similar to mine. We're the same height with the same trunk size, but your inseam is a couple cm's longer and your arms are a few cm's shorter.

Personally I'd buy the S frame due to the seattube angle of the XS. I find a 74.5deg STA can make it difficult to get the setback where I'd like it.

*Disclaimer: I have gotten a "professional" fit (Speciazlied's BG Fit) but fitters here are a joke. It was a complete waste of money. I checked with the other fitters and they'll charge $350 and that does not include any followup adjustments should they get the fit wrong the first time around. That being said, after much tinkering on my own, I'm quite comfortable on the bike.