What goes into designing a bike?

At my Studio, we, of course do a a lot of bike fits.  We also build a lot of custom bikes.  But not everyone that needs one has the dough for a full custom rig.  There are ways around having to go the full custom route, at least for some clients, but there are always compromises that take place.

This post is about how we go about finding the right fit for each client regardless of whether they are spending $15,000 on a custom carbon road bike or $1800 on a stock-sized steel hardtail mountain bike.

In the picture above is an size XS Wilier Izoard XP -- a $2500 carbon road bike.  Behind it is a Size Cycle; which is an adjustable bike we use to mock up various positions to see what the best fit is.  We can then take these raw contact points -- where the seat is relative to the bottom bracket, where the bars are then placed as far as reach and height, as well as the proper crank length.  If a client is interested in a particular bike, like this Wilier, I will mock up that bike's contact points on the Size Cycle and test from there.

Why not just get them on the Wilier to start?  Sometimes I do, but the Size Cycle allows for quicker adjustments, and makes it more likely we're going to settle on the best fit for that client, not just the best fit that's possible on that bike.  There are times, like with a client that came in last week, where the bike they were interested in would not provide the best fit, even with drastic alterations to it's components.  On the size cycle, we aren't limited by the bike, because all it's dimensions are adjustable.  To make the reach longer or shorter, I can change:

• the effective top tube length
• the seat angle
• the saddle fore-aft
• the stem length
• the bar reach
• and even the head angle (which changes how much reach the stem has).  

On an actual bicycle I can only change:

• the saddle fore-aft
• and the stem length

If I don't think we can make the bike work well  for them, I will talk to them about other options.  And, no, I don't just tell everyone they need to get a custom bike.  In this case, this client will spend less money on the bike I have proposed, than they would on the Wilier bike they were initially looking at.

So the first thing we get out of the way using the Retul infrared motion capture system is the saddle height and it's set-back from the bottom bracket.  While the set-back is important because it relies on the seat angle of the bike -- something that is not changeable once we have an actual bike under the client -- the saddle height is not of huge consequence because it is by far the most adjustable aspect of the bike via seatpost adjustment.  (we do still need to consider things like what shoes and cleats the client will use since the overall seat height plays directly with the overall saddle to bar height differential -- how much the bars are above or below the saddle).

After we determine the saddle height we begin on the reach and height of the bar.  Using the Retul, we can again make adjustments to find the optimal bar position.  We have to take into account the client's riding history (do they get numb hands, neck pain, low back discomfort?) as well as their medical history (have they had any orthopedic surgeries?  leg length issues?)

Once we have them comfortable and efficient, then I start with the 7th grade math and trigonometry.

What is my aim?  Basically to take this bar position (it's height from the ground and it's reach from the seat) and find out the easiest way we can achieve this position and STILL have room to move the bars up or down or further away or closer to the rider.  We establish this as a sort of middle point for the bar.

The reach to the bar is relatively simple -- there are only a couple variables.  We need to know how much set back the seatpost gives us, which we can use some simple trigonometry from the seat height measurement to get.  We factor in the effective top tube length, but using a measurement call the frame reach is more effective (this is the horizontal distance from the center of the bottom bracket to the middle point of the top of the headtube).  And then the length of the stem (with a bit more trig to take into account the rise of the stem and the head tube angle), is the final piece to give us the overall reach of the bike.

The bar height has more variables to consider:

A simplified list of the parts that determine bar height are (from the ground up):

• radius of the wheel and tire
• fork axle to crown measurement
• lower headset cup stack height
• head tube length
• upper headset cup stack height
• spacers under the stem
• and stem rise or height

There are a lot of limitations in these parts:

• radius of the wheel and tire -- this doesn't change much unless you get a huge tire on there
• fork axle to crown measurement -- while there are variations in fork height, we often are stuck with what a given manufacturer provides
• lower headset cup stack height -- sometimes this is zero with inset headsets (as in the Wilier above)
• head tube length -- again, can't manipulate this after the fact
• upper headset cup stack height -- varies anywhere from 5mm up to 25mm
• spacers under the stem -- most modern forks, we're limited to 35 mm of spacers
• and stem rise or height -- while we can alter the stem rise, if we need more height, 35-40 degrees, depending on the length of the stem, is usually all we can get, and this isn't necessarily optimal for handling and aesthetics

So I can do all the math and run the variables for the bar height by hand, but I have created a couple of customized excel files to make estimating the bar reach and height a little simpler. 

I can plug in certain parameters, like for instance that I want to keep the stem to only 12 degrees of rise and no more, and this will tell me what bar height I'll end up with.

I can use this to determine if the frame and bike the client is interested in will work -- if the head tube is the right length, but also is the headset integrated into the head tube or does it have external cups?  Just this small variable change can make a big difference in whether a bike will work for someone.

Building a custom bike takes more knowledge about bike fit, handling and weight distribution, but it is much easier to get the bar position where we need it because I can manipulate the head tube to almost any length I want.  This will ensure that I don't need to use an excessive amount of spacers under the stem, or a high rise stem, etc.

When dealing with a stock sized bike, we're essentially stuck with the size of bike that the manufacturer has created.  Why not just get a frame the next size up to get a longer head tube if I need it?  The problem with that is as the head tube gets longer, so does the effective top tube -- so the reach of the bike may then be too big.

It's a lot to keep track of, but we have to (yes, have to - at least in my shop) do our due diligence to get the best possible fit for our client.  Anyone can build and sell a bike, but only the most particular professional can make sure that each and every client is as comfortable and efficient as possible on their bike.

There's more money in just selling bikes and getting them out the door, but we want to make sure that the bike will feel good in the shop, and 6 months down the road.

Check back later this week, and we'll have gone through all these variables and in the process of building a client's bike.  We'll post details of the build as we go, including why we chose certain parts and accessories

Stay tuned

--J

Trail musing

The above picture is of Andy's Loop out at the Tabeguache. It has been the ugly step-child of the trails out there. Just rode down it today - figured I'd check it off the list for the year -- still no flow to it. It's really not fun to ride up or down. It's a shame because it has so much potential. It could be a killer descent, and one of the longest out in this area.

As many of you know, I live on the western slope of the Rockies in Grand Junction, CO. It's a great place -- the redneck issue is becoming less of one each year, we have great weather (we are where the mountains meet the desert), and fantastic trail systems for running, biking, hiking etc.

This time of year, we get a lot of tourists coming to mountain bike here. There was once a time when they only frequented the Loma (Kokopelli) and Fruita (18 Road) trails. Now the local's favorite of the Lunch Loop -- not called the Lunch Loops despite what the signs say -- is seeing it's parking lot full nearly every evening and all weekend long.

We're happy to play the cordial host, but please, if you come to visit adhere to a few rules:

1. DON'T ride off trail. Even when you are crossing paths in opposite directions with other riders. Just barely pull your tires to one edge of the single-track, place one foot off the trail, preferably on a rock if you can, and lean your bike away from the trail. When you ride off the trails and create a new "scar" off the side of the trail, you'll be able to come back and visit it in 2 or 3 years -- it'll still be there; the desert heals very slowly.

2. Try to ride in smaller groups. Every weekend this spring I have seen huge groups -- 15, 20, 25, even 35 (!!) riders. This can't be fun for anyone in the groups -- the fast riders are always going to have to wait and the slow ones will feel guilty for slowing everyone down, but you also create a juggernaut on the trail that can take a lot of time to get through if you're a lone rider heading in the wrong direction. If you come over in a big group, try to break up into group of maybe 6-8 at the most -- you'll be a lot more nimble, everyone will get to ride more, and you won't irritate the locals. BTW this goes for riding anywhere -- we break up into boys and girls rides when we head to Crested Butte in the summers to ride.

3. Know the yielding rules. On a mountain bike you basically are supposed to yield to everyone -- hikers, runners, horses, and other mountain bikers going uphill. If a runner/hiker sees you and steps off the trail to let you by, it's because it's expedient to do so sometimes. Thank them.......and don't get used to it.

That's all for now. I want to reinforce that we love it that we're a popular destination, but you'll have a lot more fun if you're not stepping on everyone else's toes.

The high cadence "issue"

A lot has been made of “spinning” and keeping a high cadence in the last 10 or so years. Of course, many of us have heard the story about how Lance Armstrong optimized his riding style by changing his average cadence and in the process made himself into a grand tour contender.

Here is the basis of it: higher cadence has a lower muscular cost, and a higher cardiovascular cost. Lower cadence is a higher muscular cost, and lower respiratory cost.

When the muscular system is overly taxed, like in a hard one day bike race where you rode with a high wattage, but a low cadence, it can take a few days for the muscular system to break down and repair the damaged tissue. If you're just doing a one day race and won't race again for a few days to a few weeks, then this may be just fine, and as we will find out later it may be the best game plan to do well in that race.

If you're riding many days in a row, as in a grand tour (3 weeks) or a shorter stage race (say, 5 days to a week long), you won't want to carry this muscle damage from day to day, since recovery will be far from complete, and in fact, you could experience progressive breakdown, and a precipitous decline in performance.

The higher strain on the respiratory system has much shorter term down side. The respiratory system, our lungs and heart, can recover after a hard ride within a few hours. Think about that: imagine you just did a hard ride (at any cadence) that was an hour longer than any ride you've done so far this year. Your lungs may be a little “phlegm-y” for a few hours from breathing hard, but it's usually gone by the evening or in the morning. Your legs, however, can be sore for many days after.

The more consistently you ride, and the more consistently you race, the more useful a high cadence is. If you ride only a couple days a week or, more importantly, compete only infrequently then there is not much benefit to pedaling with a cadence over 90-95 rpm.

As with most things, “low” cadence is also a matter of degree. I would consider 90-95 rpm “high”. When the magazines and websites began touting the benefits of high cadence, many cyclists, as is common for their type-A, if-some-is-good-then-more-must-be-better attitude, immediately decided if 90 was good, then 110 must be even better. I had, and still have, dozens of bike fits every year where the client is spinning madly, in an obviously uncontrolled way to reach their high target. Things brings me to two points:

Extremely high cadence: 1. requires more coordination and pedaling skill and, 2. makes small mechanical deviations more likely to create injury

Doesn't extremely low cadence can also create injury? It may, but I can say from two points that cadence on the lower end requires much less coordination and skill and it does not make mechanical deviations (like a drifting knee) worse overall – this has been born out over years of performing bike fits.  Remember those clients spinning madly on their bikes?  Well, their 3D motion capture numbers were often all over the place: Knee Lateral measurements over 50-60mm each side, Knee Angles anywhere from 6 - 15 degrees, Hip Vertical Travel measurements excessive, etc. etc.  I would then make them shift into a bigger (harder) gear, and take another view with the infrared -- voila!  Usually about a 30% reduction in the aberrant motions.  Then we were able to get down to the business of finishing their fit.

Studies have varied, but the median for overall efficiency is somewhere in the low 80s, which, in my experience, fits with the clients who have the lowest incidence of injury. (Again, this is an average or a generalization over hundreds of bike fits, but indicative nonetheless.)

So should you grind up all your climbs at 45 rpms? Of course not, but there is no good reason to spin away at 110 rpms on the flats either.

"Will weight training help me this season?"

A question I get asked a lot, especially this time of year, is about weight lifting routines.  Specifically should my athletes (runners, cyclists, and triathletes) lift throughout the winter, and if they do it, when and if they should stop lifting.


Let me start by saying that, as a physical therapist, I do think that weight-lifting is beneficial for most every athlete, but the degree to which an athlete needs to participate can vary greatly.

I think that in the dark of winter, just about every athlete could see some benefit from a few weeks of weight lifting.  Will this make them stronger in the short term?  Certainly.  But they shouldn't expect to really hang on to any of this strength once they stop, and especially as they head into the summer racing season.  What's the point then?  While I wouldn't expect to see someone really cranking out significantly more watts I think the benefits for injury prevention or resistance are worthwhile.  Some of the structural changes that occur at the tendon and bone/tendon junction can help prevent break down of these tissues during hard training phases.  I know some people may say, "Well if it helps you during hard efforts, then it must make you stronger/faster".  Maybe.  It's no guarantee that the athlete who didn't do the weight routine, would definitely get injured; nor is it clear that he athlete who did the weight routine would be able to swim/bike/run faster or harder during their intervals.

I think triathletes have the most chance for gain with the weights -- the more "whole body" nature of the sport and the fact that triathletes tend to be bigger and more muscular than their cycling and running counterparts, makes it a good match for weight-lifting.

The problem with weight-lifting and these types of sports is two-fold:

1. the extra body weight is often not helpful and often becomes a liability -- again triathletes are exempted from this a little

and

2. sport-specificity is definitely not a strong suit of weight-training

The extra muscle mass is easy to understand, but what is the sport-specificity thing have to do with it?

Put simply, some tasks (specifically pedaling a bike is what I will spend the most time on right now) are too complex biomechanically to have the strength increases transfer over from weight-training.  Think about it this way:  when you train your quadriceps in the gym what is the most common exercise?  The squat or leg press, right?  How does the brain "see" this exercise from a motor-plan standpoint?  It basically breaks down like this:

distal quads activate (eccentrically of course) first to manage patellar movement -- progressive engagement of the majority of the quad muscles -- deeper into hip flexion the gluteals/hip extensors engage progressively -- then all these muscles work concentrically to reverse the motion

The most important aspect here?  BOTH legs are working at the same time in the same direction.

So what about the motor plan of a pedal stroke on the bike:

(starting at the top of the pedal stroke - 12 o'clock)

the gastroc-soleus muscles (calves) progressively engage from 12 until about 3o'clock as does the gluteus max (rear end), but the gluteus is done with it's power phase and on the decline even before 3 o'clock -- in this same time period the quad muscles (specifically the vastus muscles and the rectus femoris) are in the middle of their engagement and declining, and their involvement flatlines around 4 or 5 o'clock -- just before 3 o'clock the hamstrings start to engage and they peak about 4:30 and start their slow decline until about 8 o'clock -- after 6 o'clock nothing much is going on, but ideally the tibialis anterior and the hip flexors would be working powerfully from about 7 o'clock until about 9 or 10 o'clock (this does not happen to a significant degree, however, for all but the most talented of pedalers) -- at 9 o'clock the rectus femoris begins it's phase and the vastus muscles start a bit later at around 10:30 -- and then we're back at the beginning.

What's the most important aspect here?  ONE leg is doing this complex sequence while the other is doing the OPPOSITE while positionally opposed 90 degrees.

The second most important aspect?  On the back side of the pedal stroke (from 6 until 9 o'clock specifically) our leg can't get out of the way fast enough of the rising pedal (and it's rising because our opposite leg is powerfully pushing it down) so everyone (yes, everyone - even the most efficient pedalers) is exerting a sort of "negative torque on the pedals with their recovering leg.

Back to the weights:  If you are training your quads/gluts to push downward with more force, invariably they will be doing so with more speed as well.  If you haven't improved your body's ability to get the recovering leg out of the way, that leg will only be exerting more "negative torque" and your net gain of power is roughly zero.  Can you train the legs to improve during their recovery phase -- basically training to improve hip flexion?  Possibly, but their is a significant limitation of this as well and it has to do with another aspect of sport or task specificity -- cadence.  Often we're pedaling at roughly 90 rpms.  Do we ever do weights at this frequency?  It's not really feasible. 

What's the answer?  If you're going to work on your strength do it on the bike where you have the specificity of the pedal stroke motor plan and where you can work on training the recovery leg to improve with the power phase.

For my athletes, I have them do specific intervals on the bike to work on strength AND cadence in a bilateral and a unilateral manner.

So if you don't get into the gym this spring after being diligent through the winter, don't sweat it too much.  Often there are other, more efficient ways to use your time.

video/picture bike fit?

The new version of the Retul software is going to come with video capability so that after capture periods with the infrared portion the fitter can show the client pictures and video of them pedaling to correlate the numbers that the fitter has from the infrared, and give it a second visual aspect.

Why did it take so long to incorporate video?  The main reason is that pictures and video are a poor means of measuring in a bike fit.  Even with expensive video systems, like the Dartfish video software, it comes down to the user placing points of rotation on a picture, and making measurements based on that.  Even with a large LCD display the picture of the cyclist might be 12-15 inches tall, at most, and placing an anchor point at the hip for instance, it would be easy to have it be "off" by a large margin. 

In fact, infrared and video systems have been tested side by side, and the video's margin of error consistently comes out to at least 10%.  Infrared measuring on the Retul usually runs at a margin of error of 0.2 mm (two-tenths of one millimeter).

Is it a big deal to be that accurate?  Even clients who are already pretty happy on their bike, benefit from the infrared because small refinements have shown large gains in pedaling efficiency and power.  10% error is too much to significantly impact aberrant mechanics and fix pain patterns on the bike, but it may help with "showing" clients very gross changes and malalignments.

So I guess it was a pretty good idea that Retul decided to use it this way.

The bike geometry problem

I know I've mentioned this one before, but it continues to cause issues every week, with at least one client that ends up on my fitting table that I need to bring it up again.

Carbon bikes can be a very good thing.  They can be comfortable (although often this is not usually a consideration of the stock bike company), they can be light, they can be stiff, and they can look cool.  The problem is that now they are cheap.  It costs so little to manufacture a carbon fiber bike that often the uber cheap and uber pricey stock frames come off the same lines, from the same hands, lay-up schedule and materials.


Okay, so that is another problem I can get into later.  The problem I want to talk about right now is molds.  Not like the fungus, but the casts that they create the frames and tubes from.  I don't have as big a problem with the frames as the forks.  If you look at the geometry charts of any major brand, and if they list the fork dimensions on the website (which more and more often they do not), you'll see that for a particular model the fork axle to crown and rake measurements are the same for every size.  Put simply, they use the same fork for every bike from 48 cm up to 62 cm.  The head and seat angles (and sometimes the bottom bracket heights) are altered between the sizes.  This doesn't seem like such a big deal until you look at the effect some of these angles, coupled with the fork rake measurements affects the handling of the bikes.

In general, the fork and frame angles are great for the "middle" size bikes -- the 54s, 55s, and 56s, or there-abouts.  But the small and the large bikes are sacrificed.  I've seen 76 degree seat angles on small bikes, and some steep head angles on the bigger bikes.

Not sure if you're bike is affected this way?  How does it handle?  Are you comfortable descending on the bike?  Do you have a "speed wobble"?  Even on the flats, do you have trouble holding a straight line?

Unfortunately, this problem is more and more common now with all the carbon manufacturing out there.  A well balanced bike fit is one way to lessen the problem, but even this has it's limitations.

Ride well.

Getting a coach

I've been coaching athletes for about 7 or 8 years now, and it grew out of a natural extension of being a physical therapist.  As a PT I need to educate and guide my clients in different aspects of their lives (strength, flexibility,nutrition, sleep patterns, body mechanics, alteration of work duties, etc.)  to effect a meaningful recovery.

Coaching athletes is at once easier and more difficult than rehab-ing.  Easier in the sense that my athletes are willing to do whatever I tell them so that they usually accomplish the goals; harder in the sense that expectations are much, much higher.  That part I like.

So what to look for in a coach?  I think there are 4 things to look for:

1. Credentials
2. Experience
3. Athletic background
4. Repoire

Credentials can be tricky.  There are many "weekend credentials" out there, so don't be fooled.  A "CPT" is not a physical therapist, but rather a "certified personal trainer" which is a distinction that can be obtained in a weekend.  USA Cycling will certify someone as a "Cycling Coach" by merely completing a take-home test.  There are many more out there -- these educational companies are a big business these days, so don't be fooled.  Do a little research to find out what it takes to become what your coach has as credentials, and lean toward people with advanced degrees in the field of the exercise science/physiology etc.  Although, this too can be a problematic since you can obtain a degree and become a "doctor" from shady "universities" that are unaccredited or have numerous times lost their accreditation, like California Coast University.  Bottom line:  do some digging, and find out what your coach had done.

Experience:  Find out who your coach has worked with.  What level of athletes has he or she worked with?  Professional?  Newbie?  As a new-comer to a sport, you may not want someone who works with pros -- they might have a poor understanding of what your needs will be, and certainly the reverse situation wouldn't work very well.  every good coach should have a list of athletes with whom you can talk to about their experience.

Your coach's athletic background is just to verify that they have undertaken the sport you wish to train for.  You wouldn't want to take advice from someone about how to train for a triathlon when they haven't done one themselves.

Repoire: Your coach should be a good communicator and there should be some semblance of a relationship between the two of you.  There is no need to be "buddies" but you do need to be able to talk to each other.

Elite athlete turned coach

I often see ads for former pro and semi-pro athletes hanging out there shingles as coaches once they retire.  This seems like a normal progression -- they've spent a number of years preparing themselves for the height of competition, so making the leap to guiding others doesn't sound like a stretch.

The problem with this lies in the reason they excelled at their sport.  I know, at first, this doesn't seem like a problem, but put simply, they could be good at their sport in spite of their training techniques.  I have read so many accounts of very talented athletes breaking all sorts of basic rules in regards to training that it has become almost routine.  There's the short-course triathlete who puts in 750 miles per week on the bike, all at long, slow pace, or the Ironman racer who puts in a 25-mile road run a week before their big race, because they "do better when they ramp up their mileage right up until race day."  In most cases, these athletes don't do things as infinitely stupid as this, but they just do what has worked for them, without regard for what might have worked better.  Many pro athletes don't alter their programs much from year to year, because "it worked well in the past so why mess with it too much."  There is not much understanding of the principles behind exercise physiology and human performance.  And, yes, perhaps breaking the rules was exactly what helped them achieve their outstanding results, but just because their top flight physiology responded to it doesn't mean that the average (or even the slightly above average) athlete will.

Elite athletes, I have found, tend to also have a poor grasp of what it "feels" like to only be able to run a 25-minute 5K.  They might have broken that threshold before they were a teenager.  I have seen a number of programs written for age-group athletes with significantly varying intensities for different intervals, which is great, except that many of these athletes didn't have this many different "speeds."  When they run, they may have their marathon pace (which is the same as their pace for any run over 45 minutes) and their 5K pace (pretty much the same as their 10K pace), and that's it.  And yet, their coach has prescribed 3 to 4 different speeds/intensities in one single workout. 

Time strapped athletes are also often ill-served.  I know Chris Carmichael just came out with a book about how to maximize training effect for the busy athlete, but this is not a new idea.  There are many of us out here that have been helping guide these athletes with time-saving, effective workouts for more than a decade.  I know amateur athletes who have been turned away by a coach because they only had 8 hours a week to dedicate to training.  The elite-turned-coach may have a really tough time coming to grips with the fact that their client is making decisions on the road whether to ride 15 extra minutes or to stop early so they can cool down and stretch.

It definitely can be confusing, so do some research and find someone you're comfortable with.  If you need to tell them to bump up or back off with the schedule more than twice, then maybe they aren't the trainer for you.

Best of luck