I’ve realised that gearing matters for Half Monty and other Ramp type tests. Why? After all the HM is performed in ERG mode for the ramp section, so surely Watts is Watts, right?
Well I did a Half Monty test at the start of the pre-tour training schedule and did really badly. I know everyone always thinks they could have gone harder but this time I knew I did really badly. In fact I was down about 9% from my last test. I went through all the usual emotions before simply resetting my 4DP Profile to what I thought I should be able to do, but I still wanted to know why it was so poor.
It happened that I listened to a recent The Knowledge Podcast where Sir Neal and Sir Mac discussed types of trainers. Not the most exciting topic but it gave me the info I needed.
I have had an oval inner chainring for a long time and was aware that there may be issues with power meter accuracy when using oval chainrings. So I always used my trainer (previously a Tacx wheel-on, now a Wahoo Kickr Core) in the big chainring which is round. However, my local bike shop recently removed the oval and fitted a round ring. It wasn’t what I asked them to do but they struggled to get the shifting to work with the oval. In fact even with two round rings they struggled and I now find on the Kickr Core the bike drops from the big outer chainring to the small inner very easily. So I was forced to train in the small chainring.
So how does this affect the Half Monty test? Well when using the small chainring and a large back cog (to get a straight chain line) the Kickr Core flywheel is going a lot more slowly that it did in the large chain ring and small rear cog. Therefore it is much more likely to end up in the ERG cycle of death that we all hate, as the flywheel has a lot less momentum.
I think this also helps explain why I am such a poor climber. I find it much harder to produce the same watts for 5-8 mins up a climb, than I do to produce that power on a relatively flat section. I think I struggle to get the pedals past the dead spots in my pedal stroke.
So going forward I am going to predominantly use my trainer in lower speed gears to force me to bring the pedals through the dead spots in my stroke and hopefully this will help me with the real goal, which is to climb better.
Sorry for long post. Thanks for reading and hopefully this will help someone else to understand themselves better.
It may also explain for some people the differences in their FTP estimates from Half Monty to Full Frontal.
OTOH - the flip side of your argument is the tendency for running a larger ring/smaller cog generates more inertia in the flywheel, which allows your muscles to cheat to an extent by providing more resistance to changes in state like rapid cadence/power shifts.
I have found that I tend to drift more to smaller ring and larger cogs for efforts requiring more rapid state changes as the flywheel’s inertia doesn’t “coast” me through the effort, and allows me to feel (and adapt to) the change more readily. (And when I’m really fatigued, I’ve drifted back to large ring/small cog to make it ever so much easier! )
Of course the other downside of smaller ring is that Strava dings you on their mileage challenges for less distance traveled.
Another small cause for a drop in power when using a smaller chainring is greater chain articulation. It’s why track riders often use a huge outer ring and a larger rear sprocket. They get the same effective gear but there is less chain articulation and a small watt saving (single percentages or less). It can be exacerbated by a not perfectly clean drivetrain though. As for pedalling up hills, I did a study on the effect of gradient on muscular activation while pedalling, you can read it here
Which likely equates to win/loss at their level. I can probably get a higher watt benefit (compared to my own effort) by not slumping in the saddle with fatigue and by tucking in my knees!
Though FWIW, when in ERG mode, I always try to minimize articulation by lining up whatever ring/cog combination I use - force of habit, I suppose.
I read your EXC study write-up, and have anecdotally observed same while using my Kickr Climb this winter. The shifting of the activation chain is really interesting, even using only a (mostly) simulated gradient effect.
I’ve managed to dodge the Half Monty and Full Frontal for a while by just nudging my numbers up a little. I know it is not considered the correct approach but I have just kept increasing all of them to the best I have hit on the road this year.
Earlier this week I went to A Very Dark Place and didn’t find it too hard so thought my numbers might need to be higher. Time for a Half Monty.
I remembered the gearing and stuck it in ERG about 1/3 up the cassette, big ring at the front.
For the first time I didn’t feel after I stopped I could have gone much harder. My heart rate hit 205bpm - I’m 51 years old. (I have seen over 210 on the road recently).
The result? FTP +1, MAP +6.
I’m pretty pleased with that and also feel that the Half Monty gives valid results for me.
Main effect of gearing in ERG mode is how well the trainer responds to power changes. Effort at a given cadence will be the same irrespective of gearing. The usual recommendation is, and what I adhere to, small ring in double or middle in a triple crank, and then choose a gear in the middle of the cassette. I usual go for the one that lines up best with the ring in use.
Ramp test is done n ERG mode so use gearing as described above. Start at your best FTP cadence (often 85-90 rpm) and don’t decrease from that. It’s OK to go a bit faster. Going slower leads to the ERG death spiral. There really are no tricks or secrets. Just do it.