Road Bike Sizing: Why It's Confusing

When things used to be simple

It used to be fairly simple to know what size of bike you were buying. For example, a 54 cm frame usually meant that the seat tube was 54 centimeters.  Most often this was measured from the center of the bottom bracket to the center of the top tube. Top tubes were almost always level with the ground, and were usually within a centimeter of the length of the seat tube (i.e. traditional geometry, figure 1). Bikes were often built in 1 cm increments, so not only was it easier to know what you were buying, but there was a wider range of sizes from which to pick than today.   

Figure 1. Traditional frame geometry

Sloping top tubes and compact geometry

Nowadays, a 54 cm bike may not necessarily mean the seat tube is 54 cm, and it may not even mean that the top tube is 54 cm. This confusion stems from the fact that most road bikes no longer have a level top tube - in other words the top tube isn't parallel with the ground (what is known as sloping or compact geometry, figure 2). Bikes built this way can have much shorter seat tubes than they used to, especially if the top tube has a slope greater than a few degrees, so the actual seat tube length is not going be of much in help in determining the frame size any longer.  Since seat tube length is no longer a good benchmark for sizing, the top tube length has become the new yardstick for bike sizing.

Figure 2. Sloping/compact geometry

Top Tube length defined

Since top tube length is now the best way to determine a bike's true size, it's important to have an understanding of how top tube lengths are measured, especially on a bike with a sloping top tube.  If the top tube is level (again, like in figure 1), then the measurement given will probably be its actual length - simple. If the top tube is sloping (figure 2), the bike manufacturer may list both the actual top tube length and/or the effective top tube length in the geometry specs. The effective length can also be known as the bike's "horizontal" or "virtual" top tube length (again, figure 2). Whatever the nomenclature, the meaning is the same - it's a theoretical number that represents what the length of the top tube would have been had the frame actually been built with a level top tube. The effective top tube length is the best way to know exactly what size bike you are buying. Here's the problem - many bike companies don't list the size of their bike to correspond to the top tube length, or they list the bikes by sizes such as Small, Medium, and Large, which really tells you nothing about the true size of the frame.

Some confusing real world examples

Let's say you know you need a bike with a 54 cm top tube. Here are some of the options you can find at the shop where I do my bike fits (Revolution Bike Shop):

1. 50s Colnago CLX 3.0 - The size refers to the seat tube length. The effective top tube is actually 54cm.
2. Medium/53cm Look 566. Although Look lists this bike as a 53cm, not a single tube actually measures 53cm! The effective top tube is 54.2 cm.
3. 54cm/Medium Focus Izalco - The effective top tube is 54.3 cm.
4. 54 cm Felt F or Z series - the effective top tube is 54.5 cm.

So, only one of these bikes actually has a 54 cm effective top tube - the Colnago, yet it's a size 50s (the "s" stands for sloping). It's no wonder I see so many people on bikes that don't fit quite right - given the variety of ways manufacturers size bikes these days it's easy to get confused.

Know your size

The moral of the story is that you really have to pay attention to the frame geometry charts, especially if you are buying off of the internet, and haven't had the chance to do a test ride. It should go without saying that the first step in your bike purchasing journey should begin by:

A) determining your ideal effective top tube length, and

B) what type of geometry is best for you (racing or performace/comfort)

 

Armed with this information, the frame geometry charts will help you quickly eliminate any bikes with geometries that may not fit your anatomy and/or riding style. 

Six Key Bike Measurements: Park Tool Positioning Charts and Tutorials

Every cyclist should have some of their key bike measurements recorded. Without this information it's going to be difficult to get your position dialed in should any of the following apply: 

• You travel, pack your bike, and need to build it up again.
• Something comes loose and slips, usually the seatpost or handlebars
• You have work done at a shop, and they accidentally change something
• You install a new stem, seatpost, saddle, and/or handlebars
• You want to duplicate your position on another bike
• You want to test ride a bike and get your position close to your current bike 

The measurements you'll want to record for road bikes* are as follows: 

1. Saddle height
2. Saddle height over bars (saddle to handlebar drop)
3. Saddle to handlebar distance
4. Saddle to hood distance
5. Saddle tilt
6. Saddle setback (saddle fore/aft) 

*Time trial and tri positions are bit more involved, so additional measurements should be recorded. The Park Tool link below will guide you through the process. 

It's important to make sure that your measurements are repeatable and consistent, and it's usually best to use protocols that are widely recognized and accepted. I use Park Tool's Road Positioning Chart to record everything; they also have a great online tutorial which will demonstrate how each of the measurements should be taken. Here are the links where you can download both the PDFs, and view the tutorials: 

• Park Tool Road Positioning Chart (one is for road, and the other for TT and Tri)
• Park Tool MTB Positioning Chart 

Here are my thoughts on each of the key measurements: 

Saddle Height 

The distance from the center of the bottom bracket to the bottom of a board or straight edge, placed across the length of the saddle (taken in line with the seat tube). Is this your actual saddle height? Probably not, because most saddles are not flat, so there will usually be a gap between the bottom of the board and the top of the saddle. The flatter your saddle, the closer this measurement will be to your actual saddle height. The more cupped your saddle, the farther this will be from your actual height. The purpose of this measurement isn't to necessarily capture your actual saddle height, but rather to establish a method that will allow you accurately record changes or transfer the same saddle height to another bike. 

Saddle height over bars (saddle to handlebar drop) 

Park Tool has two methods for recording this, and I prefer the one where you take two measurements and subtract the difference. First, record the distance from the floor to the bottom of a board or straight edge across the saddle's length (taken at the nose of the saddle). Next, record the distance from the floor to the tops of the handlers. Subtract the second measurement from the first one, and you'll know how high your handlebars are over your saddle. Keep in mind that since the first measurement is taken at the nose of the saddle, any change in your saddle tilt will also change this measurement. If you raise the nose of your saddle, it will cause the saddle to handlebar distance to increase.    

Saddle to handlebar distance 

This is the distance from the nose of the saddle to center of the handlebars at the stem. All of the following can change this distance: saddle height, fore/aft position, adding or removing stem spacers, and/or stem changes (either a different length or different rise). This measurement is typically the benchmark for "reach to the handlebars." 

Saddle to hood distance 

Although not recorded on the Park Tool Chart, I also recommend taking this measurement. It is the distance from the nose of the saddle to the tip of the brake lever hoods. This distance will change for all the same reasons mentioned just above, but this distance can also change even if the saddle to handlebar distance remains the same. Why? If you change to handlebars with different reach dimensions, rotate your handlebars, and/or change to a component group with different hoods, your saddle to hood distance can change, yet the saddle to handlebar distance at the stem will remain the same. 

Saddle tilt 

Using a straight edge across the length of the saddle, record the angle from horizontal using an angle finder, or even better, a digital level. I also recommend recording the level of the saddle in the approximate area where your sit bones rest. I have written an entire tutorial on this critical, but often overlooked, measurement. 

Saddle fore/aft (saddle setback) 

Drop a plumb bob from the nose of the saddle and measure the distance from the center of the bottom bracket to the plumb line. This measurement can change if you change the tilt of your saddle, even though you may not have changed the fore/aft position of the saddle on the rails.

Changing Saddles

You'll notice one constant in every one these measurements - the saddle. Change your saddle and almost every measure can change, especially if the new saddle has a different length. Changing saddles can be one of the most significant changes you can make to your equipment and it can really take some time to get everything dialed in to the way you had everything before the change. My advice when you are getting a new bike is to use the same saddle you've been used to riding, otherwise its going to be a real chore trying to replicate your position from your old bike. Of course, if your current saddle is not comfortable, then by all means make the switch.

Lastly, many of my clients are cyclists who had recently purchased a bike, and then found they couldn't get things to feel quite right, or even ended up in pain and discomfort; they simply couldn't figure out what had changed. Carefully recording your position and keeping the same saddle (or a new one of the same make and model) goes a long way towards knowing exactly how a different bike may change your position. 

Grand Opening! Revolution Bike Shop and HERevolution. Saturday, October 22nd, 12-5PM

Please join me this Saturday, October 22nd from 12-5PM for the Grand Opening of both Revolution Bike Shop and HERevolution (women's and kids multisport clothing and gear).

Both Revolution Bike Shop and HERevolution are located at:

235 S. Hwy. 101

Solana Beach, CA  92075

(800) 985-7814

Here's a link to the Google map.

As many of you already know, all my bike fits are now done at the bike shop, and I'd love meet those of you who haven't had a chance to stop by and visit my new home away from home.

It will be a great day of fun with FREE GIVEAWAYS, LIVE MUSIC, FOOD and DRINKS, TEST RIDE BIKES, KID FRIENDLY ACTIVITIES, and 10% OFF ALL PURCHASES MADE THE DAY OF THE GRAND OPENENING.  

The shop is a dealer for Felt, Focus, Look, Colgago and Guru, and we'll have extra bikes on hand for the Grand Opening so you can test ride some of the new 2012 bike and killer closeout deals on select 2011 models.

You can find road, Tri, mountain, communter, and cruiser bikes, in addition to a full service repair shop headed by Dan "Dano" Rock.

I'll look forward to seeing you this Saturday at Southern California's only His and Hers Bike shop.

When poor bike fit may not be the cause of your discomfort

There is an almost endless list of aches, pains, and injuries that can result from poor position on a bike, anatomical irregularities (i.e. a leg length difference), or less than ideal pedaling biomechanics – all issues that can be addressed by a competent professional bike fitter. Even if a bike isn’t the right size, oftentimes there are enough workarounds available to enable a bike fitter to assist a cyclist in eliminating, or at least alleviating, many chronic discomforts. 

There are also certain aches, pains and even injuries that definitely fall into the self inflicted wounds category – a situation where the cyclist themselves may be their own worst enemy and a bike fit may not help.  Are you doing something while logging saddle time that may cause pain that is completely avoidable, and can often be resolved without seeking professional help? Maybe you have even already been to a bike fitter for a nagging problem (maybe even me), yet you continue to be tormented by any of the following:  

• numb hands
• sore shoulders
• tightness between the shoulder blades
• stiff neck
• sore/tired lower back
• knee pain
• Achilles tendon pain
• Foot pain at ball, and/or toe numbness  

If you’d like to know some of the possible causes of these all too common self inflicted wounds, read on.

Locked arms 

It’s astounding how common this problem is, especially among recreational cyclists. Do you lock your arms out straight when riding in the hoods position? If so, you greatly increase the likelihood that you’ll get numb fingers and hands, sore shoulders, tightness between the shoulder blades, a sore neck, and even a sore back. Why? You are not using one of your body’s built in shock absorbers, which is your elbows. Always strive to keep a slight bend in your elbow, maybe 10-20 degrees; this will help keep the road vibration and jarring from beating up your body. Cyclists who lock their arms out straight also have a tendency to bear their upper body weight on their hands, which is almost certain to cause discomfort of some kind. For some, these locked arms are simply a bad habit that needs to be broken, but there are also definitely bike fitting issues that can cause these problems, and some cyclists simply can’t maintain a bend in their arms due to poor position or an ill fitting bike. Locked arms are often the result of a saddle that is tilted downwards (it seems I mention this in nearly every article), and/or being too stretched out on the bike, and/or having the handlebars positioned too far below the saddle – all are issues that can be remedied during a bike fit.  

Cadence/RPMs too low and/or pushing big gears 

Grinding away in big gears is a great way to cause knee problems, usually at the top or front of the knee. It’s also a great way to fatigue the lower back and cause Achilles tendon soreness, especially when too large of a gear is used during extended climbing efforts.  Pushing big gears combined with low pedaling revolutions can also contribute to, or cause, toe numbness and foot discomfort.  I recommend trying to keep your average RPMs (revolutions per minute) at 85+ on flat to rolling terrain and 70+ when climbing. Some cyclists will do okay staying within my guidelines on flat terrain, but will really struggle when climbing. The best solution for monitoring your RPMs is to buy a cycling computer with cadence functions, and then work toward retraining your leg muscles to spin more quickly. Some cyclists would be better served by actually changing their front chainrings, and will want to switch to a compact crankset (commonly a 50/34 tooth combination). If you are already using a compact crankset, then you might also consider a rear cassette with a lower bottom gear (i.e. 26-28 teeth; SRAM offers their Apex group with a 32 tooth low gear).  Less experienced or heavier cyclists may even be better off with a triple crankset, which will give them a much wider range of lower gears from which to pick.  If you think you are too strong to need smaller gearing, but can’t maintain at least 70 RPMs when climbing long grades, your ego may end up causing some possible down time due to sore a sore knee or Achilles tendon.

Riding too much 

As we age it becomes ever more critical to allow muscles and connective tissue to repair after hard or long efforts. I hate to be stating the obvious, but as we get older, we simply don’t recover as well as we once did. Ligaments, tendons, and cartilage seem to be particularly susceptible to strains and tears as the body ages. Adequate rest needs to be part of every cyclist’s game plan. Many will ride for years and years with poor positioning and less than ideal biomechanics without the slightest pain, and then suddenly something will go wrong, usually after about 40 years of age; I see these folks on a weekly basis. It would be nice if I could offer simple guidelines so you could gauge the amount of down time required to avoid pain and injuries, but there are simply too many variables involved – every cyclist’s situation in unique. Poor bike fit and the stress of exercise are but two factors in the equation, as there is an almost endless list of things that can inhibit the body’s ability to recover, with work and family stress at the top of the list. If you are an experienced cyclist and you find yourself with an ache or pain that you can’t connect to a sudden change in bike position, and you ride hard and/or long more than three days per week, your body may be telling you it’s time to cut back. It’s also possible that a long dormant issue has finally reared its ugly head, your body can no longer repair itself between efforts, and you’re going to need some professional bike fitting help.

The “weekend warrior” syndrome 

Of course, the flip side of riding too much is not riding enough.  Even if you have ideal position on the bike and near perfect pedaling biomechanics, if you go out once a week or only on the weekends, and ride hard and long, you’re more than likely going to have some discomfort.  This is especially true for those who ride hard on both Saturday and Sunday. I also find those who do a group ride on the weekends, but don’t ride the rest of the week tend to really dig far too deep. Many “weekend warriors” do avoid injury, since their bodies have adequate time to recover before the next suffer fest, but they are often riding in discomfort. This discomfort can of course be caused by issues related to poor bike fit, but it can also be a simple matter of lack of miles – a tired back, butt, and legs can be your constant companions once your weekly ride extends past a couple of hours. If you experience discomfort on even short rides during your weekly outing, then it is probably time to see a bike fitter.

Choice of frame material

Aluminum frames can beat up your body; this despite the use of a carbon fork. I know there are some frame builders out there who may take exception to that statement, but I rode on an aluminum frame with a fairly relaxed geometry (shallow seat tube, longer wheelbase, longer chainstays) for a couple of years and would never do so again. I found aluminum to be fairly harsh and jarring, which is not going to help with a wide variety of discomfort and pain, most notably hand numbness, neck and shoulder pain, lower back fatigue, and saddle soreness.  Many newer cyclists don’t want to spend over a thousand dollars on a new bike, and since most manufacturers will offer aluminum frames on their entry level bikes, it should come as no surprise that I see many new to the sport complaining of issues I can often trace back to jarring. Steel frames are more forgiving, as is titanium, but those frame materials are rarely seen on an entry level performance road bike, especially titanium.  Steel used to be very common on lower priced bikes, but nowadays it’s usually aluminum. Carbon fiber is usually going to be the next available option after aluminum, and if you can afford the extra money, I’d strongly suggest doing so.  As the next best option, which is usually not quite as expensive as a complete carbon fiber bike, you might also consider an aluminum frame with carbon fiber chainstays, seatstays, and/or seat tube. Lastly, aluminum can be a good choice for those who compete (particularly in criteriums), and want a bike that is both light for climbing, and super stiff for sprinting.

Cleat Placement: Fore/Aft Position

Myth vs. Reality

Many widely practiced bike fitting protocols and procedures are based on little more than traditions handed down from fitter to fitter through the years. In many cases there is good reason to follow these rules - time and again they have proven to be the best approach. Yet, there are other fitting protocols founded on "wisdom" that amounts to little more than old wife's tales, such as setting the distance from nose of your saddle to the center of the handlebars to match the distance from your elbow to the tip of your middle finger. Another one of my favorites is setting your reach to the bars based on whether or not the front hub is obscured by the handlebars when you're in the hoods position (I've already written two articles discussing reach to the handlebars, both here and here, and you'll find neither of these outdated methods mentioned).  

Metatarsal bones (blue/green area)

Standard Fore/Aft Cleat Positioning

Another standard fitting protocol that may not be entirely correct is the traditional way the fore/aft position of the cleat on the shoe has been determined. Conventional wisdom almost always uses some variation of the following: 1. locate the first metatarsal head - the boney bump on the outside of the foot, just below the big toe (see the above illustration; it's the area where the green shading meets the light grey area below the big toe); and then 2. affix the centerline of the cleat so that it runs directly through this spot or just behind it (you'll now have the cleat positioned over the ball of your foot). Also, the larger your feet, the farther behind the first metatarsal head the cleat should be positioned (up to 1cm or even more). Following this guideline, it is oftentimes difficult for those with an above average foot length (US size 10.5+, or Euro size 44+) to position the cleat far enough to the rear.

Midfoot/Arch/Heal Cleat Position

There are fitters who have broken with tradition, and have taken an extremely different approach to cleat positioning, advocating a midfoot/arch placement. I even saw a guy out riding recently with the cleat placed directly under the heel of his shoe. I'll admit, I have no experience with these methods, since both would require drilling new cleat holes in the shoes and affixing new threads. I don't possess the expertise to attempt such a solution, so this is one theory that will go untested in my practice, at least for the time being. It's also worth noting that moving the cleats this far to the rear could create a potentially dangerous amount of toe overlap with the front wheel.     

Finding the Sweet Spot

I'd like you to try an experiment. If you have access to some carpeted stairs, try bounding up them bare footed, taking maybe two stairs at time. Notice where you launch off of the bottom of your foot with each stride up the stairs (I'll bet it's not your midfoot/arch). Wouldn't it make sense to affix the cleats so that the center of the pedal spindle (also center of the cleat) is also located in this same place on your foot? Bounding up a flight stairs seems to closely mimic standing on the pedals during a climbing effort or sprinting, doesn't it? Those are definitely two instances where you want maximum force applied to the pedals. I know this little experiment doesn't exactly qualify as a scientific study demonstrating where peak forces are generated on the foot when cycling, but it certainly passes the common sense test. It's too bad we can't precisely locate this sweet spot on the balls of our feet and shoes, and affix the cleats there, as well.

Another Alternative

So, somewhere around the ball of the foot seems to make the most sense for the cleat placement, yet following this guideline still leaves many cyclists plagued with toe numbness, burning sensations, and pressure points ("hot spots") on the balls of their feet.  The typical advice to cure these issues is almost always to move the cleat even farther back, placing the cleat closer to the heel - sometimes this works, sometimes it doesn't, and sometimes it make the situation worse.  I find this solution effective for a surprisingly small number of my clients. Often, foot discomfort can also be cured or alleviated by moving the center of the cleat ahead of the first metatarsal head, approximately in line with the second metatarsal head (again, see the above illustration; it would be the "knuckle" located below the second toe, which is actually closer to the front of the foot). Could the almost universally accepted approach for cleat placement simply be wrong? Is the second metatarsal head the better place for the fore/aft positioning of the cleat? I haven't come to any definitive conclusions, but it appears this location is certainly a better spot for some cyclists.  

Trial and Error

Today's super stiff carbon soled shoes can sometimes minimize the need for locating the ideal fore/aft position of the cleat. Yet, for some, these same stiff soles actually seem contribute to foot discomfort, so it seems likely that cleat placement still plays some role in foot comfort, regardless of sole material or stiffness. The "best" cleat position may also be partly determined by one's preferred pedaling cadence - I've noticed those with higher pedaling speeds (95+ revolutions per minute) tend to prefer the cleat more forward on the shoe, while those with lower RPMs seem to prefer a more rearward position.  Saddle height, saddle fore/aft position, and saddle tilt may also have some impact on cleat positioning. I could go on and on, but I think you get the idea. Ultimately, this is one fitting protocol that doesn't lend itself well to a simple formula or universal procedure - the ideal fore/aft cleat placement may vary widely from cyclist to cyclist, and it may take a bit of trial and error to get it just right.

Persistent Problems

If you are plagued by chronic toe numbness and/or burning sensations on the balls of your feet, and have already tried moving the cleats both forward and backward without relief, it could be that your shoes are the problem - either the shape of your shoes is just not a good match for the shape of your feet, or as mentioned earlier, the sole may be either too stiff, or not stiff enough.  It could also be that your particular pedal model or shoes don't allow the cleat to be either moved far enough forward or backwards (Speedplay makes a baseplate extender to address this issue). Some cyclists also get relief from the commercially available footbeds/insoles made by Specialized, eSoles, Superfeet, and the like.  Lastly, any of the following could be the root cause, especially if the discomfort is only on one foot: cleat rotation, improper stance width, leg alignment issues/need for wedging, pelvic asymmetry, leg length differences, and basic positioning errors. Sometimes, no amount of self help is going to do the trick, and it could be time to see a professional bike fitter who specializes in the foot/pedal interface. 

Update (7/16/11): Too much or too little room in your shoes can certainly contribute to foot discomfort. I had a client who had been tormented with hot spots/burning sensations on his feet for months and they went away immediately after he switched to a thicker sock. I suspect a thicker insole may have also done the trick. Some may have the opposite problem, and should try thinner socks. Some people even need a different thickness of sock for each foot.

Low cadence, big gear mashing can also cause foot discomfort. If your pedaling RPMs (Revolutions per minute) don't average at leat 75, especially on relatively flat terrain, try using smaller gears and make an effort to get the RPMs up to 80+.  RPMs can really drop during extending climbing efforts, so take special care to use appropriate low gearing to keep the pedals ticking over at 70+ RPMs.