bagi

For road cycling, is a size 56 frame suitable for someone 183 cm tall? What sizing do you recommend based on experience?

SoSmellyAir

While a size 56 frame of a certain model may well be suitable for someone who is 183 cm tall, it may not be suitable for you even though you are also 183 cm tall.

It really depends on the ratio between leg length and torso length, and (to a lesser extent) torso length to arm length. See the description under Body Dimension here: Stigmata - Gravel Bike | Santa Cruz Bicycles

In addition to that, different bikes may have significantly different frame geometry even though both bikes are nominally a size 56. Stack, reach, and effective top tube length, among others, are more relevant measurements to compare between different bike frames.

datlas 

It’s complicated as it depends on your proportions and flexibility as well as bike’s geometry.

If you are “average” proportions you probably want a 58cm bike over 56, but that’s just an educated guess.

These decisions are often best done in person.

Jrasero

56cm to 58cm

BUT this heavily dependents on the bike brand and geo and your overall body.

I ride anything from a 47cm-50cm but I also have comfortably ridden 44cm and 52cm bikes

best thing to do is go to a bike shop and pick the bike you think you want and sit and preferably ride the bike in the 2-3 most suitable sizes. Or if you have a bike already that fits you, compare the geometry to the geometry chart of the bike you want

And even if you get the frame and reach right you still probably need to think about bar width and crank length which isn't always suitable off the rack

Iride01 

And even if a 56 cm frame of a particular model is the correct size, you might not care for the position it gives you. IE, Race fit, very relaxed fit or somewhere in-between. So that's also a consideration for you.

But as mentioned, just because a 56 cm frame of one model might be the most ideal size for you doesn't mean every model of bike/frame in a 56 cm is the ideal size. It's really best to try out the bikes and see what you like. A few places will still let you ride them for a while. However that's getting fewer and fewer. But a ride in the parking lot isn't as good as a 10 mile ride. I did both with my last bike purchase and the 10 mile ride had me picking the opposite size bike of the parking lot ride.

Welcome to BF!

eduskator

It's not as simple as comparing a number with another number. I measure 185cm and like my bikes a little smaller than the average so I usually buy 56cm / ML frames if the other specs are within the range that I like.

What's your inseam (inner leg length)? This does also make a difference when determining the proper frame size for you.

Note that for most bikes, the XXcm is not an actual measurement of anything (it used to be or can sometimes be the seat tube lenght). It's a number to indicate the approximate size and this is why some brands choose to put letters instead as frame sizes (Giant and Canyon for instance).

PeteHski

56 or 58 would likely fit depending on a load of factors and personal preference.

tFUnK

I had a co-worker who is 6'4" borrow my 58cm Cannondale roadie and while it worked I think ideally he should have been on a size larger. Lots of variables as others have mentioned. I am 181cm and can ride 56 or 58 but I prefer 56. I can get by on a 54 or 55 with a 110mm stem but a 56 or 58 with a 100mm stem feels right for me.

veganbikes

Maybe? but also on the flip side of that coin...maybe not? There are a lot of factors involved with fit and a number on a frame and someones total height isn't really going to help any of those factors. The total height yes but inseam plays a part and reach and other considerations and a 56 frame is not a 56 frame necessarily because I have seen numbers and ridden bikes and they don't always match up.

bruce19

Previous comments have said what I'm about to say. Sizing a bike using only height can be a big mistake. I start with my inseam (82.55 cm) and multiply by .667 (LeMond formula). This puts me at approx. 54/55 cm frame size. Bear in mind this uses a virtual TT not sloping TT. FWIW I have had a couple professional fittings and this is what they determined too. Based on fittings I also know that my TT should be approx. 55 cm. So, as some would say, a "square" 55 works for me.

eduskator

To add to my other reply, a 58cm bike will also have bigger components (IE 44cm bars instead of 42cm, longer stem, crank arms of 175mm instead of 172.5mm). This said, if you are in between, I'd get a 56cm for sure if you feel good on the bike.

DaveSSS 

I agree with starting with cycling inseam. Mine is 84cm and I'm only 168cm tall (long legs). Using TT length and frame size numbers is outdated and meaningless these days. All brands I've looked at list stack and reach. Those two numbers tell all you need to know about fit. I do pay attention to the seat tube angle, just in case a model has a too steep STA and a proprietary post with only 15-20mm of setback. On a small frame, 74-75 degrees is common.

Stack should be selected based on your preferred saddle to bar drop. I use around 11cm, so I use a stack of as little as 505mm if I plan to use a -6 degree stem or up to 525mm if I use a -17. With a short torso, I avoid a reach of over 380mm.

Jrasero

I agree. Maybe this is just a short guy concern, but if I can't clear the bike to begin with I believe I shouldn't be riding that size. This obviously isn't the case with taller people and/or with bikes with compact frames with sloping TT. From there look at reach and stack, but IMO this is really predicated in knowing your reach and stack numbers to begin with and IMO that only comes from riding a lot of bikes and reading a lot of geo charts

crazyravr

For reference I am 188cm tall and ride M/L Defy with 120mm stem. Fits like a glove I like smaller fitting bikes with longer stems.

eduskator

At 188cm on a ML Defy, you must have a short inseam? Did you leave all spacers on your fork tube? That seatpost must be close to its maximum height!

crazyravr

Almost at the line. Removed couple spacers. I have 88cm in seam.