What Size?   Don’t feel bad if you are not sure what size bike you require – I’ve seen seasoned roadies and triathletes rolling around on frames that are either too large or too small.  Further compounding the bike sizing question is the huge range of geometries and components that make answering this question quite difficult.  Following on from the article in the last edition, I’m going to provide you with a quick reference guide to finding your perfect fit on a mid priced road bike.  I’ll also point out a few things to consider that will help making this bike easy to fit up with some tri bars come race season.     OK, so what size reasonably priced roadie do I need that I can also use for tri?  Good question.  The two most important measurements you need to understand are the effective top tube length and the head tube length.  As long as you buy a bike with the correct top tube and head tube lengths, the rest of the bike geometry will pretty much take care of itself (that’s a slight exaggeration but you’ll soon see what I mean).  Lets deal with the top tube first.  The difference in length of the effective top tube between the smallest adult road bike (for someone about 5ft 2’) and the largest adult road bike (for someone about 6ft 5’) is only 10cm.  I say effective top tube because for some time now bike manufacturers have been making frames with top tubes that slope down towards the seat tube.  They do this to make the frame stiffer and a bit lighter (otherwise known as ‘compact geometry’).  This has become very common on most frames but it makes measuring the effective top tube (the distance between the top centre of the head tube through to the centre of the seat tube in a horizontal line) more difficult.  Why do you want to know the effective top tube?  Because for most of us the effective top tube of the bike should correspond with our arm length.    To find out what size you need, do the following:  Stand upright but relaxed and let your arms hang by your sides.  Have a friend prod your shoulder, feeling for the centre of the socket joint.  Now run a tape measure down the arm to the base of the wrist.  <insert diagram>  For shorter people this measurement will be about 49-54cm, mid sized people will have a measurement of around 53-57cm and the taller among us will measure about 55-59cm.  The arm measurement that you record will be reasonably close to the effective top tube that you need.  eg. a person who stands 173cm tall might get a measurement of 53cm resulting in requiring a bike with an effective top tube of between 52-54cm.  Most frame manufacturers publish both the sloping top tube length and the effective top tube length.  Simply match your arm measurement to the effective top tube length and voila you will know your frame size.       Is that it?  I thought it would be more complicated than that…   Don’t worry; it is a bit more complicated.  Once you know the effective TT that you require and you have a short list of bikes that you like, its time to look at a few other factors.  First of these is head tube height.  Generally speaking, those of us that can stretch down and touch the floor with flat hands are far more flexible than those of us that struggle to tough our shins, much less our toes.  Perform a quick stretch test.  If you can go hands flat to the floor you don’t need to worry about the length of the head tube on the bike.  For the rest of us a taller head tube will work better than a shorter one.  The reason for this will be apparent come tri season when you bolt your shiny new aerobars on the bike and try to put your elbows where your hands used to go.  Once you want to go aero, most road bikes don’t have a tall enough head tube to allow you to reach the aero bars without causing you to loose power through the pedal stroke.  The solution to this is to either run lots of spacers under the stem (somewhat ugly and dangerous) or buy a bike with a taller head tube in the first place.   So the two most crucial bits of information you need to know to figure out your correct size is your arm measurement (corresponding to the effective top tube length of the bike) and a selection of frames with slightly taller head tubes (a good example of this is the Colnago Ace) which shares the same geometry of its bigger brother the CLX except that it is 20mm taller in the head tube in every size making it an ideal road/tri bike.     A few other thoughts…   Test ride the bike.  I can’t stress this enough.  Borrow a friend’s, hit the shop up for a spin, steal one (and later return it).  The reason that the test ride is critical is for two reasons.  Firstly, you may not like the ‘on-road’ ride of the bike.  You won’t find this out on the wind trainer or by patting it; some bikes just don’t ride well under some people.  I’ve ridden $15K bikes which I didn’t like as much as some $3K bikes.  There was nothing wrong with the bike; it just didn’t feel good to me.  Back your own judgement on this one.  A bike ‘feels’ bad to ride is not likely to get better just because you paid for it.  Secondly and very importantly – check out the steering.  It needs to track straight and turn smoothly.  This is vital if you are planning to attach aerobars and hang most of your body weight off the front end of the bike.  Bikes that feel skittish and shaky will feel even worse once you put the tri bars on.  Your road/tri bike needs to feel good to you and it needs to be manageable to steer when you rest most of your weight on the handlebars.   Also… Take a tape measure into the bike shop with you and don’t be afraid to use it.  The geometry charts provided by the manufacturers can be out by up to 15mm on some bikes and some of the floor stock may not have a size printed on the bike.  Once you know the effective TT you are looking for its easy to run a tape measure over a bike and see if it’s going to be your size.   And lastly.  I don’t care how cheap, how much on special, how much of a ‘deal’ a bike is – it must fit or it’s just an expensive paperweight.  The argument that the seat post and stem are adjustable to make the bike fit is an outright lie.  The adjustability of these components is there to make a bike that fits you, fit you perfectly.  They are not there to shoehorn a XXS onto a six foot man or squish a 5ft6’ woman onto a megadeal bike with a 60cm effective TT.  If you are in any doubt about a certain bike size being right for you, then ask.  Ask the shop guy to explain why they think the bike fits you, check with your friends who understand bike fit or a coach.  The point is if you are in any doubt about a frame fitting you, then don’t buy – learn more first.   So that is a quick summary on finding a road/tri frame to fit and how to knock out some frames that don’t.  Get this piece right before you consider groupsets/wheels/weight or any other factor.  Bike fit comes first and all the bits and pieces follow on from that.