I just realized that Specialized and Giant make 6 sizes of their frames. I think this is why I am having a hard time fitting on their bikes. Which manufacturers offer more sizes?

In the world of compact geometry, offering six sizes is very generous. Standard geometry (horizontal top tube) bikes from large producers usually were offered in 2 cm increments of seat tube length. Even so, fit was not so easy with them, because of the need for stand over clearance and the short head tubes. With 6 sizes of compact frames 3 cm between seat tube sizes would cover a 18 cm range (46 cm to 64 cm for instance) which is plenty. And the 3 cm spacing should be no problem for fitting on a compact frame as standover is no issue and the head tube heights are more generous.

When you say you are having trouble fitting on a bike, do you mean in reality trying out bikes in a shop, or do you mean trying to match the catalog specs to your measurements? With compact geometry it is really very simple. You find the size that has the top tube length and head tube height that you need or the closest match. You adjust small discrepancies in top tube fit with stem length. You adjust small discrepancies in head tube height with the number of spacers you use under your stem and also the stem angle. Within the range of sizes Giant (for example) offers, you shouldn't be more than say 10 mm of stem length or 10 mm of spacer height away from your optimum fit. Those discrepancies are easily corrected with stem and spacers and are essentially a non-issue. The only problem I could see that doesn't fit into this category is if you are off either end of the range, i.e. too big of their largest size or too small for their smallest. I hadn't thought that was the problem.

Another approach instead of correcting discrepancies with stem length and spacers is to shop for fit. Despite the nominal similarity of bike sizes among different brands, each brand has a different geometric formula, longer or shorter top tube, and taller or shorter head tube to name just a couple of the areas of difference. So there are many more than six sizes, just not within one brand. You have to compare the different brands to get a sense of all that is available.

Do you mean smaller increments between sizes or a greater range of sizes? If you are fairly normal in proportions and fit requirements, all manufacturers offer small enough increments that can accommodate a proper fit through appropriate selection of components and subsequent adjustment.

Every manufacturer has slightly different sizing, so a 56cm Specialized is not quite a 56cm Giant. Given that there are literally dozens of companies making excellent frames, there isn't a huge need for that many frames. Colnago has many more sizes I believe. Colnago can afford to do more frames because the lugged construction is much easier to vary than a monocoque frame. Ultimately, since you can swap stems, it just doesn't really matter. I ride a 57cm frame, with the correct stem, I can find the same position on a 54cm frame.

If you're having that much trouble finding a bike that fits, I suspect something else is off.

I suspect troller error

Colnago Master comes in 17 sizes. Buy now!

Then there is that! Several such posts in a row.

6 sizes is plenty. If you can't get a good fit with 6 sizes, you're probably looking at the wrong style of bicycle for your riding style and fitness level.

c'mon do it!

No mass produced frameset with their endless compromises and monotonous sameness will meet your precise & exacting requirements.
A full-on custom is the only way to go.

-Bandera

That obsolete thing will never do, it doesn't even have a carbon fork.

If you want to have fun, you can look at this fit calculator... hehe

https://www.competitivecyclist.com/St...ulatorBike.jsp

Yep; becoming tiresome ... time to hit 'ignore'.

Tsunami https://tsunamibikes.com does custom aluminum frames starting at $800
Sanner Cycles https://ww.sannercyclies.com does custom lugged steel frames starting at $1500
Nelson Titanium Products https://ntpbikes.com does custom titanium frames starting at $1800
Quiring Cycles https://www.quiringcycles.net does custom welded stainless frames starting at $2300

I've ridden titanium for 17 years but have to say stainless steel with contrasting fillet brazing has a certain elegant appeal.