Which muscles does a tri bike help? (Page 2)

Quite a number of years ago I applied to a program to become the first pilot to fly a human powered aircraft across the English Channel. It was called the Daedelus Project.

As part of the engineering behind the project student engineers at MIT and Cornell University experimented with different orientations of the pilot/human engine to yield best aerodynamics and most effecitve power transfer. At one point an ergometer- exercise bike- with 180 degree adjustment for seat angle was developed for testing difference effective "seat angles"- from prone recumbent to supine recumbent and everything in between.

The study yielded little measurable difference in power output through the 180 degree arc of power transmission to the drivetrain from the rider/pilot. Ultimately, the pilot was placed in a conventional bicycle orientation, roughly vertically oriented. Here is a reference:

http://en.wikipedia.org/wiki/MIT_Daedalus

What we learned from Daedalus, and subsequent studies, is that seat tube angle does not exert an effect on pedal power.

But Keep Reading...

Early bicycle designers arrived at the roughly 72-73 degree seat tube angle from a rudimentary observation of the lower anatomy. They noted that the quadriceps group of muscles: vastus lateralis, vastus medialis, vastus intermedius, rectus femoris and the large muscles below the knee- the gastrocnemius, tibialis group and soleus, seemed to do most of the work in the pedal stroke. The 72-73 degree orientation seemed to facilitate that.

Interestingly, they were right. It was an impressive accomplishment at the turn of century (1800's to 1900's) given the lack of diagnostic equipment in sports then.

Fast forward to the late 1970's, early to mid and late 1980's when triathlon is born and popularized. A guy at Scott USA named Boone Lennon invents the aerobar after Pete Penseyres uses a rudimentary version in the Race Across America (RAAM).

Soon after two enterprising lads with fast wives, Dan Empfield and Ralph Ray, designed a bike specifically built around the aerobars (and for women, their wives). As Dan Empfield told me back in 1987- "It is built from the aerobars back".

The bike opened the angle between the femur and the torso at the top of the pedal stroke facilitating a more comfortable, open torso to femur orientation. It made using aerobars more comfortable. This was the first popular triathlon bike, the Quintana Roo Superform. The first bikes had 80 degree seat angles. The prototypes had 90 degree seat tube angles. The angle eventually moderated to the current status quo of 78 degrees.

What Empfield and Ray did not realize at the time, was that- while the steeper seat tube angle was more comfortable for use with aerobars than a traditional road bike, that most athletes ran faster after riding a steep seat tube angle bike with aerobars than after riding a road bike.

This was quantified in a study called the "Garside Study" by Ian Garside and Dominic Doran published in the Journal of Sport Sciences in June, 2000. Athletes did, empiracally, test faster running on a treadmill after cycling on an indoor trainer with a steep seat tube angle. Since the test was performed indoors on stationary apparatus, the variables of environment (wind, temp, etc.) were limited.

Since the Garside study a few studies have emerged repeating the protocol and debunking the result. The debunking of the Garside study has, however, been largely debunked itself. Empfield writes about the controversy (and confusion) here:

http://www.slowtwitch.com/Tech/What_science_says_of_seat_angles_222.html

That's the science.

Now, the opinion...

I started triathlons in 1984. No aerobars, no steep seat tube angle bikes. When I met Dan Empfield in the combined HED/Quintana Roo booth in Long Beach, California at the annual bike show I had already been using his wetsuits. He gave me a bike. I rode it. I was faster on the bike and run.

Years have gone by and I have raced through several "eras" of the sport, hundreds of triathlons on every continent where triathlons are raced. Bottom line: I know I am faster on a tri bike. Both on the bike and on the run.

In 1986 I did the Bud Light Ironman World Championships in Kona, Hawaii. I finished in about 11:37:00 something on a conventional road bike with clipless pedals and bladed spoke, tubular tire wheels: state of the art for that time.

Years later I did Ironman Canada, a much more hilly course. 10:27:00 something. I went back to canada again and went just over 11:00:00 hours. Despite the fact that I was much older and had a huge shopping list of injuries I still went considerably faster on the new technology/aerobars, steep seat tube angle bike.

"Attempting to be aero" on a road bike... I should have been more clear. Most people, when on a road bike fitted as a road bike, will still try to drop their upper body in an attempt to decrease resistance (unless they're drafting in a peleton). Doing this for a long time IS detrimental to trying to run afterwards. Opening up that hip angle again (via a proper tri fit) will alleviate that hip issue and make it much easier to run off the bike. In that way, a tri bike DOES spare muscles for the run.

Thanks Tom, was hoping you'd chime in.

Your knowledge never ceases to amaze me.

I think it is interesting  that someone can dismiss the tri-bike helping the run as a "Myth".

In this sport we talk about "fit" being so crucial, and in a fit we make adjustments in centimeters and millimeters.  Every minor change moves the way your body moves and the way different muscles pull on various muscles, and/or joints.  With that said the geometry of a tri-bike is different from a road bike, no matter how you try to adapt the road bike.  So there is no possible way that the two different bikes can not have different affects on your body, and hence change how you run. Everything we do during a triathlon is interrelated.

as far as the original post i would say your glutes had something to do with your stride after you are fatigued.  But that is just a guess.

I have no evidence one way or another.

I'll just say that most people who say they run better off a tri bike than a road bike started with a road bike...then moved to a tri bike.  It doesn't make sense to start with a tri bike and race tris, then buy a road bike to race tris and compare how they run off the two. 

That being said...when someone takes an extra $1000-$5000 out of their pocket to invest in a second bike...one that is tri specific...it is usually accompanied by an increase in training, dedication, and excitment for the sport.  Those factors probably play a big factor in why people now may feel they run a lot better off the bike than they used to.

I started with a road bike, did my first ever tri with clip ons, then got a used TT bike as I knew I was hooked.  For those 3 other tris I did with my TT bike in my first season, I struggled to run much more off the bike than I do this year.  The primary reason why I run much better off the bike this year is 99% due to my increase in bike and run fitness.