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How to size the Crux frame set

David Hudson Oct 23, 2013 02:50PM PDT

Debating between the 49 and the 52 Specialized Crux carbon disc frame set. I normally ride a 51 road in cervelo, I'm 5'6" with a little under a 29" inseam.

Normally I would go with the 52 since 49 SOUNDS so small, just looking at that raw number for size, (anything in the 40's sounds really small, like for a 5'3" women or similar), but, of course, it's just a single number, and there's more to it than that.

My current Scott Team cross frame is "labeled" a 52, but shares similar measurements to the 49 crux in some areas (in others it's a bit closer to the 52 crux.) I like my Scott, and consider it to fit relatively well, but if someone were to ask me "if it's not perfect, would you consider it a slightly too big or slightly too small" - I would say slightly too big. Not much seat post sticking out from my seat tube!

For standover and top tube, my scott is right in between the 49 and 52 Crux, but the Reach and Stack measurements are quite interesting--the 49 Crux is almost identical in both to my 52 Scott.

Consequently, I'm leaning toward the 49 Crux. Thoughts please. Thank you!

(virtual) Top Tube for Scott: 525
Crux 49: 513
Crux 52: 537

Standover for Scott: 763
Crux 49: 754
Crux 52: 773

Reach for Scott: 370
Crux 49: 369
Crux 52: 375

Stack for Scott: 541
Crux 49: 541
Crux 52: 554

Up 2 Rated Down
Kyle Blomquist Oct 25, 2013 08:26AM PDT SPECIALIZED Agent
Hi, David!

Fitting a bike to a rider is an important process that directly affects the ride quality and comfort of a bike - but it's one we can't tackle online.

The best fail-safe method for determining proper size is to stop by your local Specialized dealer and let them provide you with a technician's fitting. The experts at your Specialized dealer are skilled at bike fitting and will help you find the appropriate size to fit your individual needs. You can also take the opportunity to test ride bikes in different sizes to see what feels best for you. We recommend the following when test-riding for size:

Pay heed to how your body feels differently on the different bike sizes. Is your torso cramped? Are you too far extended? Are you positioned too uprightly? Too aggressively? Also pay heed to how well you can control the bike in different sizes. Does the bike feel too snappy and uncontrollable? If so, it is probably too small. Is it too sluggish and delayed? If so, it is probably too big.

You can find contact information to set up a test-ride at your nearest Specialized dealer here:

There are many factors that go into determining which frame or bike size is best for you. Fitting a bike is similar to fitting clothing in that even though one particular size might be the size which is intended for your basic measurements, you may find that a smaller or larger size is more comfortable for you personally. This is because each person's physical dimensions and attributes (arm, torso, or femur length; flexibility, skill level, etc.) are slightly different, which can lead to different frame size requirements even for people of the same height.

If you are between sizes, we generally recommend going with the smaller size, as is it easier to make a smaller frame fit a little larger than the inverse.

Differences in bike sizes are felt most in the relative distances between the pedals, saddle, and handlebars. All of those distances can be manipulated to a degree on any frame size by swapping out crank arms, seatposts, or stems. A bike or frame of optimal size will generally have you riding comfortably with stem, seatpost, and crankarms all at middle lengths and not at either extreme.

It is possible to provide rough guidelines based on your height and inseam length, but these are only a starting point for a proper fitting with your local Specialized dealer. has a great resource which provides this rough guideline here:

If you have additional questions in regards to sizing, feel free to contact your local Specialized dealer or email us at You can also call us M-F 8:00-18:00 MST at 1.877.808.8154.

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