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What size road bike should I get?(6 posts)

What size road bike should I get?Herm
Nov 14, 2001 6:58 PM
I am 6'1 and a half, i will most likely reach 6'2 considering I am only 16 and probably going to grow a slight bit more. I am just wondering generally what size people usually get at that height. also I forget how much room I should have between my crotch and toptube when standing over it.
Thanks in advance, Herm
Careful here . . .jacques
Nov 14, 2001 8:18 PM
Herm, you need to rethink your question a bit. The room between your crotch and the top tube when standing over it, you need to forget about. With proper sizing, you'll have plenty. Here's how to take a shot at proper sizing:

1. Find your crotch-to-floor distance. To do that, take your shoes off. Cram a big book, spine up, into your crotch. At the same time, jam the book against a wall. Mark the wall where the top of the book spine rests against it.

2. Measure from the floor to that mark on the wall, in centimeters. Multiply that number by 0.65. That's a ROUGH, theoretical frame size guide. (For example, if you measured 89 centimeters from the floor to the mark on the wall, your theoretical frame size would be 89 x 0.65 = 57.85, rounded off to 59 centimeters).

3. With your theoretical frame size written on a piece of paper, approach some knowledgeable bike riders and ask them to help you pick a frame. They might look at you and decide that you would do better on a 57 centimeter frame with a long top tube, or perhaps on a 60 centimeter frame with a short top tube. It depends on your build - more specifically, on the ratio between your lower body (legs) and upper body (trunk and arms).

Don't let anyone make you straddle a bike and pronounce cheerfully that you have "just the right amount of room over the top tube." That method of frame sizing sells a lot of bikes, but it's no good for serious riders.

Good luck.
Some good advice hereGregJ
Nov 14, 2001 10:16 PM
Go here to read a bit more on this. Pay particular attention to the part about TALL riders. I think you may find that the .67 advice will put you on too small of a frame.

Know that bike makers measure their frames in different ways, so a 58 c-c in one brand may be equivalent to a 61 c-t in another. Bikes differ in top tube length as well as height. The folks on this board frequently get very wrapped up in finding a bike with just the right top tube. They are right to a point but it can be very confusing to someone purchasing a first bike and buying a bike by top tube length may not be feasable by the choices available in your local shops. I would not fret too much about it. Stems are easy to change and your local shop should be able to swap a stem out if it is determined that you need something longer or shorter than what comes on your size bike.
re: look for sloping top tubedzrider
Nov 15, 2001 5:16 AM
It's not likely that you'll find a bike that fits perfectly both today and the day you reach your full height and weight. I didn't stop growing until I turned 21. Bikes with sloping top tubes are meant to accomadate a wider range of sizes by using longer seat posts. If you get one that is as big as you can comfortably and efficiently use today, it will allow for more growth before it's entirely too small.
ditto on sloping top tubebigrider
Nov 15, 2001 8:33 AM
That is right on. Get a bike a little to big for you now with a sloping top tube. Use a short stem (70 -90) to get the proper reach. If and when you grow you can raise the seatpost for your longer legs, slide the seat back to fit your longer femurs, and lengthen the stem up to 130mm to fit your longer torso. Leave extra on the tube steerer of the fork so you can adjust w/ washers. Or better yet buy a threaded headset bike so you can adjust it if you could find it on a new bike.
The problem with a non sloped top tube is if your standover height is maxed and the top tube fits you now if you grow there is no ability to lengthen your reach unless you buy a bike with a long top tube length design like a lemond and put a short stem on it to start out with.
Colnago C40 B-Stay + Free Campagnolo Carbon Crank + Wheelset Prince
Nov 16, 2001 4:13 PM
Hi Herm

Generally guys who are 6'1" wiegh in at around 195 lbs.

When we fit these bikes to big guys we usually supply the Colnago CT1 or C40 with sizes 62 cm C-T

Here is the formula.

0.67 x Inseam Length (cm) = C-T Bike Frame Size.

Note one thing about Colnagao their top tube is relatively short.

It could that relative to your legs you may have longer or shorter torso and arms. So even though you have the correct bike size (seat tube length), the top tube can sometimes be to long or short.

So sometimes with Colnago because of the shorter top tube you may have to fit the bike using top tube length.

This is the formula to size top tube length ;

(Torso Length + Arm Length) / 2) + 4  = ( Top Tube + Stem)

Note three important thngs about fitting Colnago ;


If the seat tube length gives you the right top tube length + stem length then fine use 0.67 x inseam.

Go ahead and buy a Colnago C40 from me, contact me at and I'll give you the most unbeliavble of offers.


Having used the above two formulas ;

A. Seat Tube ;

0.67 x Inseam Length (cm) = C-T Bike Frame Size.

B. Top Tube + Stem Length ;

(Torso Length + Arm Length) / 2) + 4  = ( Top Tube +

and the top tube is too long then what you have to do is buy a frame with the correct top tube + stem length.

The top tube can be longer because you have relatively
shorter torso and arm length.

This will mean a slighlty smaller Bike Size (Seat Tube Length).

This will give you the correct top tube + stem length.

However, the seat tube length will be to short for you.

Since you want the correct seat tube length i.e. Correct Bike Size, you will have to use a 350mm 27.2mm Campagnolo Carbon Seat Post, this extra long seatpin will give you back the cm that you lost in sizing the top tube. ie gives you a longer seat tube length.

The Colnago Carbon seat post is 28mm, what you have to do is insert a 0.8mm metal tube into the Seat Tube.

How high will this seat post be ?

Work out what your bike size = 0.67 x Inseam Length.

The difference between the bike size (0.67 x Inseam length) and the seat tube length is how much Seat Post Length you have to add to the seat tube. This gives you the correct total Seat Tube Length.

For example, you size is 56cm C-T the seat tube is 54cm to give the shorter top tube. You are short of 2 cm in the seat tube so just add 2cm of seat post length (insert the seat post into the seat post and just bring it out 2cm) .

Note you will have to use this as the base for adjusting the Saddle Height (0.883 x inseam length) with the additional 2cm.

However, in most cases the stem length can take care of this problem. But for a minority of people they would have to pursue the above method.


If the top tube length is to short. Use the Top Tube + Stem length formula to get the correct top tube length for your torso and arm length. This could be because you have relatively longer torso & arm length and relatively shorter legs.

This will give you a longer seat tube, but because you have to fix saddle height at 0.883 x Inseam length, this will give you a relatively shorter saddle height ( relative to seat tube), you will be well within your saddle height even though your seat tube length is longer.

For example your .67 x Inseam gives you a size of 54cm

this bikes top tube length doesn't fit you.

You have decided to go with a 56 cm Size Seat Tube Length because this size gives you the right top tube length to fit your long torso and arms. However this might give you a seat tube length of 58cm.

4cm more than required.

But because your saddle height is 0.887 x Inseam = 71.4 cm this is still longer than the seat tube length of 58 cm. So this bike will fit you no problem.

Note one important factor when you adjust up and down top tubes like this. This can change your SADDLE TO STEM DROP. No problem. You can raise the handlebars up or down into the correct position by using Spacers. You can increase the bar height by 5 inches or 11 cm.

Did you get all that ?


It is always a trade of between Seat Tube and Top Tube. Depending on your relatively shorter or longer torso arm and leg lengths.

If you are going to buy a Colnago C40 or CT1 buy from me. Contact me at and I'll give you the most unbeliavble of offers.

Even if you don't buy from me let me kow how you find this information and how you get on. You can post a reply to this message or just email us.

One last thing don't go into a bikeshop to buy a Colnago buy having the salesguy getting you to stand next to the bike. This will be disastrous.


Ever saw a 6' guy with a long torso and short legs ?
Ever saw a 6' guy with short torso and long legs ?
Ever saw a 6' guy who is between those two ?

Ever saw a 6' guy with a long torso, short legs and really really long arms ?

Yes you have. It's the guy at the cycling club who humiliated you. Quick throw him a banana.

So in your case you would have to start with a 9cm stem. As you grow you just replace the stem with 10-11-12-12-14 cm Stems.

Without knowing your Inseam / Torso and Arm Lengths I can only give you an example. You can post a reply with your dimensions or email me with your dimensions and I'll give you the correct bikefit.

Here is the example ;

Get this.

0.67 x Inseam = Bike Size C-T

0.67 x 81.5 cm = 54.6 cm = Rounded Up = 55 cm C-T / Seat Tube Length

A Colnago 55cm C-T seat Tube equates to a 54.3 cm Top Tube.

If your "cockpit" length is 68 cm this means that the difference of "Cockpit Length 68cm - Top Tube Length 54.3cm = Stem Length 13.7 cm

The Colnago C40 comes with the Colnago ITM Stem.

The ITM stem comes in lengths from 9 cm to 14 cm.

Since you need only an additional 13.7 cm cockpit length, you will need a 14 cm stem.

You can just about fit. So relax your not yet a gorilla.

Your saddle height is 0.883 x Inseam 81.5 cm = 72 cm ( 55 cm Seat Tube + 17 cm Seat Post Length. )

For later, note that your seat post length is 17 cm

goog noos ?

Ha ?

Note one very important thing when fitting any bike, if you buy a frame which is exactly your size, then this will be a tight fit. You should always buy a frame slightly bigger than your actual bike size, because this gives you a more comfortable fit.

Do you know that you can even have a 9 cm Stem and 59 cm Top Tube (Cockpit length 68 cm - 9cm Stem Length = 59 cm top Tube Length)

A Colnago with a 59 cm Top Tube has a 64 cm Seat Tube.

Since your saddle height is 72 cm (Your saddle height is 0.883 x Inseam 81.5 cm = 72 cm) and the Seat Tube is 59 cm. This means that the Seat Post length is 13cm (72 cm saddle height - 59 cm Seat Tube Length.)

How you noticed anything ?

The 55 cm bike gave you a Seat Post Length of 17cm

Seat Tube Length of 55cm

Saddle Height of 72 cm

Top Tube Length 54.3cm

Stem length 14 cm

Cockpit length 68.3

The 64 cm bike gives you a Seat Post Length of 13cm

Seat Tube Length of 64cm

Saddle Height of 72 cm

Top Tube Length 59cm

Stem length 9cm

Cockpit Length 68 cm

With a 68 cm cockpit length

you can have a longer stem 14 cm and a shorter top tube 54.3 cm

or you can have a shorter stem 9 cm and a longer top tube 59 cm

either way note how your cockpit length remains the same at 68 cm.

With a 72 cm Saddle Height

you can have a longer seat post 17 cm and a shorter seat tube 55 cm

or you can have a shorter seat post 13 cm and a longer seat tube 64 cm

either way note how your saddle length remains the same at 72 cm.

Did you get all that ?

No you didn't.

For all this to sink in you'll need an hour or two.

Let me know how you get on.

Over and out.