Jim Manton's thoughts on bicycle fit and aerodynamics from his seminar at Tri Town Bicycles.
Jim Manton is the founder and owner of ERO Sports. He is regarded as one of the world's best bicycle fitters and top cycling aerodynamic experts.
Below are Jim's key thoughts and points from the Bicycle Fit and Aerodynamics Seminar held at Tri Town Bicycles on 8/6/19. Audio files can be found at the bottom of the post.
Thoughts on Bike Fit
- Many cyclist tend to run saddle too high
- A common mistake is for rider to 'drop the heel' or 'push the heel down' during the down stroke. Results in knee hyper-extension (read our prior blog post on "How To Make an Effective Pedal Stroke")
- Many triathletes ride too far forward, result is have to "hold themselves up" to prevent falling/sliding off front of saddle.
- With that said, you don't want to be too far back either... there is a balance point he is looking for.
- The humerus (upper arm) should not be perpendicular to the ground (this would result for most riders in a position that is too compact).
- Most riders are not stretched out enough.
- Getting aero is not only about getting low.
- Ultimately the 'aerodynamic fit' goal is to get you as small as possible, but w/ the understanding that an unsustainable position will be slow due to the need to come out of the aero tuck.
- "Always trust what you feel"
- Get shoulders in as narrow as comfortably possible.
- Jocelyn McCauley has the bicycle fit of the future.
- The "mantis" position tests fast, but requires a "cup" armrest to be comfortable. Every person Jim tested has been ~15w faster in the mantis position.
General Thoughts on Aerodynamics:
- "Aero Pecking Order":
#1 Bike fit and position.
#2/#3 Helmet and clothing are interchangeable based on individual rider.
#4 Race wheels
- Only thing as bad as a flat shape when it comes to aerodynamics is a cylinder shape. Unfortunately our body is mostly round, cylinder-like shapes.
- The "dimples" on golf balls (or some wheels and clothing) roughs up the boundary layer of air around an object resulting in less drag.
Thoughts on Clothing/Helmets/Equipment:
- Triathlon bikes are getting about as fast as they can get.
- "Skin is slow"
- A fast skinsuit can offer more time savings than a race wheelset
- Helmets: if your position is good, most of today's aero helmets are testing fast.
- Helmets that test consistently fast are the Giro Aerohead and Louis Garneau P09.
- One of the worst aero helmets is the Rudy Project (didn't clarify model).
- One of the best suits of all time is the Louis Garneau skin suit. It consistently test fast on all athletes.
- Hair on legs/arms tends to 'rough up' air too much. A bit of stubble may be faster than smooth skin but has not confirmed this.
- "Behind the Saddle" (BTS) hydration systems are not always aero, but tend to work well for most athletes.
- Disc wheels are always the fastest option.
- Race wheels are important, but tire choice also priority. Not all wheels test fast with different tires and tires width.
- Going from a Continental Gatorskin tire to a Grand Prix 5000 could save 15+ watts.
- One of the fastest wheelsets he has ever tested is the ENVE 7.8, but only with a 25mm tire.
- HED wheels are almost always near the best in regards to aerodynamics, and work well with most tire sizes (unlike ENVE reference above).
- Downtube water bottle not a big aero penalty and can be better than a BTS option if it allows you stay in the aerobars for longer.
General Thoughts for the Triathlete:
- Triathlon is a sport that favors economy of effort.
- If getting more aero gains you 5min of free speed for your bike-leg, it would be wise to only bike a couple min faster for the bike leg and use that saved energy to run faster.