CymruMog

I wonder if any bike fitters, or those with a better understanding of the field than me can help? I currently ride a 52cm Condor SuperAccaiao and a S Canyon Grail alongside a M Orange Clockwork MTB. Different bikes for different terrain, so not directly comparable (Condor & Canyon not a million miles off each other though). I want to buy a Vitus ZX1 EVO, but can't decide between S and M sizes. I want it to be closer to the Condor in terms of fit. In comparison:
Condor - Reach 384mm, Stack 533mm, ETT 537mm, ST c-t 520mm, HT 135mm
Vitus S - Reach 381mm, Stack 522mm, ETT 537mm, ST c-t 490mm, HT 112MM
Vitus M - Reach 387mm, Stack 543mm, ETT 551mm, ST c-t 510mm, HT 130mm
According to the height chart I'm pretty much bang in the middle. I know a bike can be made bigger, but not smaller (within reason), but bought a Diverge last year that was too small so am now super-nervous about getting a mail order bike wrong again.
Just looking for some views as I gather some info to try and make a decision.
Many thanks.

Iride01 

I'm not a fitter. I've just messed and experimented with my fit on my bikes all my life. I also try things just to see what it does. You can do that too. You won't be harmed permanently in the process. Here are my thoughts...

Seat tube length alone doesn't tell you anything. Saddle height is driven by your leg length and that will need more than just knowledge of the seat tube length. You need to know if the saddle on the smaller size will get to the height you need without exceeding it's limits for the seat post length. It probably will since you apparently ran their sizing calculator. Seat tube is aero, so probably their design and not one that you can easily get a longer one if needed.

The HT I'm thinking is the head tube length. Can't imagine why that should matter. The head tube length is pretty much driven by the frame stack that the designers wish to have for that size bike and the 700C wheel and fork that will be on it. What concern do you have for head tube length?

If you want to compare fit as in your actual position on the bikes to your Condor, then you need to be looking at where your butt and hand positions are. So measure from the saddle to where you put your hands on the hoods and on the drops. And also the difference between the saddle height and the bar height. Then you'll have to figure out on the other bikes where that will be. So knowing stem length and bar reach & bar drop of all the bikes will help with that.

If you've got your bars on the Condor at their max height or have gone to extremes to give you a different bar position from what is normal for it, then you probably shouldn't be comparing for the same frame stack and reach. As well, the frames are different materials with designs for their different qualities. So there'll be differences that will seem odd to you that some equate with their comfort even though it's just different. And probably there are little differences of tube angles, bb drop, handlebar width, fork rake and trail that will also give you a different perception

So the same fit might not be what you really want. You just won't know until you ride the bike in the conditions you intend to ride it in for the amount of time you intend to ride.

oldbobcat

Read geometry charts, relate them to the bike you're currently riding, know some of your own dimensions, and understand your body morphology. I classify bodies into five types, gorilla, tyrannosaurus, dachshund, spider monkey, and average. I'm sure you can picture their characteristics. Each type has its own fit concerns. For instance, gorillas on endurance bikes with tall head tubes and short top tubes (high stack to reach ratio) might find themselves sitting up too high. Dachshunds and tyrannosauruses need to beware of too much handlebar drop. Spider monkeys have to watch out for too much reach. Most stock frames are built for averages, but some models disfavor certain types. Study them.

Kontact 

Curious how the stack can be within 11mm but the HT is 24mm different. That just demonstrates how these kinds of measurements aren't standardized.

Anyway, it looks like the small Vitus is closest to the Condor. You'll need one extra 1cm spacer.