Over the winter, I made a couple changes to my bike to address some things I thought I could improve my bike split.
1. I went from a compact crank (34/50) to a mid-compact crank (36/52). This was to address spinning out on downhills
2. I reduced the crank arm length from 165mm to 150mm. This was to open up the hip angle.
Both changes worked. Much less spinning out and the more open hip angle made for more comfortable running off the bike. I got busy training with this new setup indoors over the winter and was hitting some good power numbers. Once I got outside, I was riding my normal routes and despite putting out more power, I am slower. I am riding the same Trek Speed Concept with the same Favero Assioma Duo power meter, wheels, helmet, front hydration etc.... Also... I am the same weight at 145 lbs.
I have 2 examples of identical rides one training and the other Ironman Chattanooga 70.3. Here are the results from my garmin 520
Training route Before Changes After Changes
53.4 miles 53.4 miles
2:43:55 time 2:47:35 time
172 avg pwr 199 avg pwr
182 nor pwr 207 nor pwr
80 avg cad 80 avg cad
19.5 avg spd 19.1 avg spd
IM Chatt 70.3 Before Changes After Changes
56.7 miles 56.7 miles
2:29:33 time 2:40:40 time
172 avg pwr 178 avg pwr
183 nor pwr 199 nor pwr
80 avg cad 86 avg cad
22.8 avg spd 21.2 avg spd
The way I see it, there are three things that can be the cause....
1. Favero Assioma Duo power meter is not reading the same. This seems unlikely because they have a reputation for being consistent. There has been a firmware update but again this seems unlikely.
2. I don't understand the affect shortening crankarm length has on the power output to the wheel.
3. Some unrelated issue sucking up watts. I installed bbinfinite derailleur pulleys and bottom bracket bearings, new chain and rear cassette for the beginning of this race season. There is nothing apparent to me that is binding while the bike is on the rack. I am going to take it to a local shop and have my drivetrain inspected to be sure.
Any ideas would be greatly appreciated
1. I went from a compact crank (34/50) to a mid-compact crank (36/52). This was to address spinning out on downhills
2. I reduced the crank arm length from 165mm to 150mm. This was to open up the hip angle.
Both changes worked. Much less spinning out and the more open hip angle made for more comfortable running off the bike. I got busy training with this new setup indoors over the winter and was hitting some good power numbers. Once I got outside, I was riding my normal routes and despite putting out more power, I am slower. I am riding the same Trek Speed Concept with the same Favero Assioma Duo power meter, wheels, helmet, front hydration etc.... Also... I am the same weight at 145 lbs.
I have 2 examples of identical rides one training and the other Ironman Chattanooga 70.3. Here are the results from my garmin 520
Training route Before Changes After Changes
53.4 miles 53.4 miles
2:43:55 time 2:47:35 time
172 avg pwr 199 avg pwr
182 nor pwr 207 nor pwr
80 avg cad 80 avg cad
19.5 avg spd 19.1 avg spd
IM Chatt 70.3 Before Changes After Changes
56.7 miles 56.7 miles
2:29:33 time 2:40:40 time
172 avg pwr 178 avg pwr
183 nor pwr 199 nor pwr
80 avg cad 86 avg cad
22.8 avg spd 21.2 avg spd
The way I see it, there are three things that can be the cause....
1. Favero Assioma Duo power meter is not reading the same. This seems unlikely because they have a reputation for being consistent. There has been a firmware update but again this seems unlikely.
2. I don't understand the affect shortening crankarm length has on the power output to the wheel.
3. Some unrelated issue sucking up watts. I installed bbinfinite derailleur pulleys and bottom bracket bearings, new chain and rear cassette for the beginning of this race season. There is nothing apparent to me that is binding while the bike is on the rack. I am going to take it to a local shop and have my drivetrain inspected to be sure.
Any ideas would be greatly appreciated