I am planning to buy a bike on bikes direct and I know my bike size is 50cm (I'm 5'6). However, the bike I'm planning to buy says the bike for people my height is 46cm. Does anyone know whether there are any inaccuracies with the bike measurements on bikes direct? Or should I just go with what the website says and buy the 46cm?



https://www.bikesdirect.com/products/..._al_xi_sc1.htm

Just curious, what's your inseam? (Jam the spine of a book up your crotch and measure from the spine to the ground.)

To save time converting the Geometry Chart numbers, standover height for the 46cm frame is 29.1in and 50cm frame is 30.4in. While standover height isn't everything, we can at least get a better idea of which route to take.

My inseam roughly 29.5inches.

I would do some of the online fit calculators then call or email BD directly. From what I've heard, they are very helpful in making sure you get the right size.

The 46cm frame would be the proper size.

I would be very careful with that evaluation. If you are going to order a bike have a look at the specifications listed with each bike. Compare this to the bike you are presently riding and then select from there. I purchased from Bikesdirect and was really pleased with the bike, but not with their recommendation for fit. Thankfully I have ridden for years and knew the specifications req'd. Beware!

I ride a 56 from one bike company and a 58 from another. You can't necessarily compare one brands size to another. I got burned by this once when I bought a used bike on Ebay. Buying without riding it is to some degree going to be a guess. Therin lies the problem with buying online.

Of course, just getting the frame size correct is only the first step in a good bike fit. Then there are all the other variables. A good LBS would, of course, help you with this and change out parts (usually for free) that need to be changed to get a correct fit.

I would go with what the website says, after writing them or emailing them about your concern, prior to the purchase. Then after the purchase, if you need to exchange the size, due to improper fit, you should meet less resistance.

Size 46 in that particular bike has an effective top tube measurement of 53cm. That sounds about right for someone 5'6".

I just ordered the sc2 which is the same frame and got the 46.. I am the same height as you.. You have to pay attention to the other sizes in geometry and compare them.. 46 is the right bike even though you could get away with the standover on the 50 the bars will be too far forward. It through me off at first too.

Compare the saddle to bar reach of your current ride to the reach of the frames you're interested in. Call BD and ask them to measure it for you. Safer to go smaller and buy an additional longer/higher stem if you have to, but if you're a non-competitive rider or live in a mountainous area you might prefer a shorter reach, perhaps even shorter than the stock set-up.

If you are between sizes, I would definitely get the smaller size.

You pays your money, you takes your chances. Read the geometry charts, flip and coin, decide.

That bike is a relaxed geometry bike. As an example, I'm 5'9" and ride a "medium" Giant OCR-C which also has a substantially relaxed geometry. The actual seat tube measurement of the "Medium" Giant is 50cm and a perfect fit. But if I try to ride a standard frame with a 50cm seat tube, it would be too small. Given the sizing chart from BD, I'd recommend that you buy the small, 46 cm frame that BD recommends for you.

Hey, I have a 47 X 56.5 custom bike with a sloping top tube among others in varying std sizes. A std frame a 53 or 54 fits my "stand over" (sorta) but the top tube is too short as I have a long trunk, so I normally buy a 56 and let my "boys" tickle as the top tube length is more important. A short top tube makes your rear wheel jump off the ground when climbing or sprinting hard. I'm careful with the getting on/off part. Most bikes are "square" with equal top and main tube lengths, some, like some of the Italian brands, are "short" with the top tube 1cm shorter than the seat tube. A few companies make em long (+ 1 cm on top) and a few offer square, long or even short options in their production models

It depends on your relative measurements. At your height, but with very short legs and a very long body, I ride a 50 cm, relaxed geometry, Lynskey Sportive frame giving me only a fraction of an inch clearance for the dangly bits, but I still need a 120-130mm stem with no spacers for reach.

Call them up and get their opinion over at BD. I'm sure they'd be more than happy to help you out.