Modulus

What the heck is "modulus", also known as Young's Modulus or the Modulus of Elasticity?  We see it with carbon fiber: "this road bike made by The Coolest Road Bike Company Today is laterally stiff and vertically compliant thanks to the high modulus carbon used in the frame."  

Since I'm back in school and taking tests, exams and quizes, here's one for you.  Which has a higher modulus:

A) Glass

B) Rubber

C) Magnesium

I'll give you the answer at the end.

Before we talk about how modulus can effect the way a bicycle rides, lets get some definitions out of the way. Stress is defined as a force over an area.  The unit is the Pascal (Pa  which is also N/m^2) or in english units, the familiar psi (pounds per square inch).  Strain is defined as the change in length over the initial length.  This is a unitless measurement (inch/inch or meter/meter) and is given as a percent or part per million (ppm).  Now that we've got that out of the way, we can see that the modulus (E) is defined as:

or simply, stress over strain.  Since the strain is unitless, the modulus is reported in Pa or psi (metric and english units respectively).  

"Hey, that's great and all, but what does it tell us?"  

Good question.  It does NOT tell us how strong something is.  Nowhere in the above equation do you see ultimate strength.  What it does tell us is how stiff something is.  

Think back to my quiz above and let me rephrase it.  Which of the materials listed is the stiffest? Disregard strength and you'll likely get the right answer.

So what does this have to do with bicycles?  Modulus is mostly mentioned with carbon fiber and here's why.  As Jon pointed out last week what we call "carbon fiber" is really Carbon Fiber Reinforced Plastic (CFRP)  And that plastic is... well, not something you'd build stuff out of by itself.  What it does do is bind all those thin fibers together, helping to keep them from buckling when a compression load is applied.  The higher the modulus, the stiffer--or more resistive to bending--and individual fiber is.  Since the fibers are all pretty darn strong, using a stiffer fiber allows the builder to use less of them to make that "laterally stiff" bicycle frame.  Less fibers equals a lighter weight frame.  

What about that "vertically compliant" bit?  That is usually achieved by mixing fiber types and laying up the cloth in different ways--by changing the orientation of the fibers.  Shape of the final tube also plays a HUGE part in the overall ride.

What about metal?  Steel and berylium are way up there in stiffness and aluminum is near the bottom of the list for metals.  Now, which bikes tend to ride the harshest?  That's right, aluminum.  Why?  I just said that aluminum has a relatively low modulus so it should have a low stiffness, right?  As anyone who has ridden an OLD Vitus aluminum frame can tell you, aluminum, when built to the same dimensions as steel, can be a very flexy ride.  The reason that modern aluminum bicycles are so stiff is due to the tubing size.  In order to eliminate the flexy-flyer feeling of those early aluminum frames, the tubes grew in diameter while shrinking in wall thickness.  This stiffened up the aluminum tremendously while retaining its lightweight advantage over steel.  If you were to build a steel tube the same dimensions as an aluminum one, the steel would be over the top stiff.  

So, to sum up, modulus is the stiffness of a material--a starting point, if you will.  From there, the builder adjusts the tubing shape and--in the case of carbon fiber, the lay-up schedule as well--to get the ride that they desire, whether that ride is ultra-stiff, more forgiving or somewhere in the middle.  

And the answer is: A) Glass.

Progression

I'm a numbers guy. I like to know my heart rate, the air temperature (to the nearest tenth of a degree, thanks), how fast I'm riding (+/- 0.1 mph), what my maximum speed was (again, +/- 0.1 mph), how far I went and, thanks to the ubiquity of GPS devices, where I went (with elevation, please).

However, when I want to know this information has changed over time.

I've been running computers on my bikes for... well... longer than I care to mention here. Let's just say that my first computer was a CatEye Solar. Man, that thing was huge! I also had the Solar II, which was even larger. Since then, I've had too many computers to list.

Until now. As the batteries have died, instead of replacing them, I've just removed the computers from my bikes.

I strap my watch to the bars so I know the time (I often have a narrow riding window, so not knowing the time is not a luxury), but otherwise, the only thing on my bars is my light.

At first, I missed knowing all of this information. It was similar to when I had to return the Edge 705 to Garmin, I really missed having that device on my bars. (Actually, there are times that I still do... but I digress.) Now, I just log my ride with my phone using a program that ties into the built-in GPS. I keep the phone's screen off, and it's stashed in my jersey pocket. I don't look at it during the ride at all. However, when I get back from the ride, I have all the numbers I want. It's my record of the ride.

I wrote about the three ways to use a GPS: routing, logging, and the displaying of information. Of these, the only I am using now is logging. What is the effect of all this? I am free to just ride. I still get my numbers fix, but I don't let it interrupt my ride.

Going from a state of high complexity and lots of information at my fingertips to no information and increased simplicity is the right kind of progression.

What's going on here at LAT

You might have noticed that we’ve been slacking off a little.  It’s Jon’s fault.

OK, not really.  

I thought I might take a minute and let you in on what’s been happening around Lactic Acid Threshold.  Last fall I decided to return to school.  So, I kept the day job, scaled back the hours a bit and hit the books full time.  I managed to keep up my riding—and writing—and kept up with my reviews.  Then Winter Term happened.  My riding slacked off as I struggled to keep up with my classes.  I managed, but not as effortlessly as I had hoped.  I continued to work the day job, too.

While all of this was happening, Jon’s day job picked up as well, so both of the LAT writers were buried.  

The end result was that our thrice-weekly posts dropped off.  

We’re heading back to prime riding season and our posts should begin picking up.  It’s an odd fact, but when we aren’t out riding outside it’s much harder to write.  Riding on the trainer just doesn’t quite cut it.  But, since the riding season is back underway*, we should be getting back to our more regularly scheduled postings.  Thanks for sticking with us.

*That and my day job is no longer a hindrance.

New Gear: Bont Road Shoes

Carbon fiber is, by itself, not stiff. It's basically a cloth. However, when combined with epoxy resin, the result is both very strong, and very light. Of course, as cyclists, we all know that carbon is light and stiff. No surprise there.

Let's talk about this plastic--this epoxy resin--that engulfs the carbon fibers. Imagine one such plastic that got soft and malleable at relatively low temperatures. What you have is custom, heat-moldable carbon.

The Bont cycling shoes I just received use one such material. 160 degrees in the oven makes the shoe hot (but not too hot to touch), and just soft enough to mold as it cools. These shoes are light, stiff, and moldable. In fact, they can be molded as often as needed.

It turns out, that's a good thing. So far, I haven't gotten the molding right. They seem fine until I get on the bike and start riding, at which point, they start to hurt. Hopefully, I can get them right and get in some long time with them in the coming months.

Where I Started

It’s dumping rain—with snow predicted later this weekend—and I’ve been thinking about cycling and how I got started.  I apologize ahead of time for the less than upbeat post.   

First, I grew up with bicycles.  My first bike didn’t have training wheels.  My dad taught me to ride in the parking lot of our apartment building over the course of the weekend.  I was so banged up the second day, from all of the falling down that happened the first day that I my dad had to literally pry me away from the railing so he could finish teaching me.  I was perfectly happy to stay a non-cyclist forever.  

Instead, I ended up learning to ride, and I’ve ridden ever since.  I’ve now been riding for more than 30 years.  Riding was freedom to me.  We used to go all over the neighborhood, leaving the house whenever we could.  We’d ride in the woods and on the street; we’d make jumps—you know, the plank of wood and a cinder block—and we’d ghost ride our bikes, too.  And, for the most part, it was a family affair.  My family has three boys, one of them you know—Jon, the other poster on Lactic Acid Threshold, is my younger, taller brother—and we would ride all over the place.  Usually, though, I was chasing after Mike, my older brother.  

In fact, my first real crash happened very early on—if I remember correctly, I must have been 7 or 8 years old—and Mike was the one who got me home.  I smacked my head pretty good and was unconscious.  There were no helmets back then and I was moving pretty good, nearly 40mph I’m sure, really, on a 16” wheeled bike.  Yeah, at least 40… and hit some gravel.  Down I went.  I woke up at home.  Man, that was a weird feeling.  

I continued to chase Mike as we grew up.  He was fast.  I got into mountain bikes around 1986—that first mountain bike was a Schwinn Mesa—and he stayed in the road bike world.  Naturally, this made it hard for me to keep up on the road, but I justified it by telling him that I was having more fun.  Now I do both.  

Mike no longer rides.  He had to hang up his wheels for good around 1995, or so, after being diagnosed with Multiple Sclerosis (MS).  

MS is an autoimmune disease that attacks the central nervous system.  It inhibits the communication that happens between the neurons of the brain.  Because of this, Mike can no longer ride a bicycle.  In fact, he has trouble walking and standing now, and mostly is wheelchair bound.  

This week is MS Awareness week.  Bike MS is a charity event that happens all over the United States.  Chances are, there is going to be one in your neighborhood some time this year.  I’d like to challenge you to pick an event and ride it.  Like cancer, there is no cure for MS, but strides are being made to improve the lives of those who have it, and to lessen its impact in their lives.

Next time you ride, think about how you got started.  I know I will, and I’ll be thinking about Mike.  

Transition to Spring

I'm losing my patience.

After years of riding indoors, like all cyclists everywhere (that's a sweeping generalization I don't intend to backup with fact, by the way) I'm ready for the winter months to be over. Actually, the last few days have been gorgeous. The threat of rain has never turned into anything but a threat. Sure, it's been windy, but even wind, the greatest of all my nemesi, er nemesises... nemesisisi... Whatever.

Even wind would be welcome after being indoors. So, I swap out wheels, get my gear together, and bring my bike to work in the hopes that I can get in a lunch-time ride. Heck, I even got into Outlook and scheduled the time with myself. But, for two days in a row, the force of evil at work have conspired against me and I've had to work through lunch. Today will be no different.

The problem is, once I've made up my mind to get in a real-live-outside-moving-around-getting-somewhere ride in, it's difficult to bear going back indoors. In addition, I can no longer just roll out of bed in the morning and find my roller-setup ready and waiting. Suddenly, I have to prep again for riding indoors. And doing that--making the time and making the changes necessary to get on the rollers again--means I'm no longer ready to dash outside at a moments' notice.

At this point, I've suffered through the long cold darkness of the winter and I don't want to waste all the fitness I've tried to keep by being too lazy to switch configurations, but I'm tired of needing a backup plan to get on my bike.

I need shorter work days, and more free lunch-times (there's no such thing as free lunch--even under this administration). This morning, I made the change and got back on the rollers. If the rain/snow doesn't come tonight, I might even try riding outdoors tomorrow again.