Difficulty in ERG mode while changing chainrings

[bradchang]

Hi,

Does anyone have the experience that after changing chainrings (for example from 52/36 or 50/34 to 48/32 or 46/30) I did feel the difficulty increased on same target power (under ERG mode)? Even keeping same cadence under same watts level, feel intensity is getting higher. Why?

Brad

[chidlow]

Probably one of the biggest threads on this forum, enjoy!

Big vs Small Chainring - Same Power (ERG Mode Gearing)

I recently did the Antelope workout which has 10-min intervals at around 90% FTP. Since I use a smart trainer in ERG mode, I normally do not shift gears and just leave it in my small chainring and a cog that makes the chain straight. Five minutes into the first interval, and holding a cadence of 85-95 (Antelope recommendation), I found myself really struggling. I shifted to the big chainring and one cog easier (one cog easier just to offset the big chainring a bit), and finished the second and …

[jdman]

Yep - it is a huge can of worms. My advice - don’t! If you time trial on flattish roads like on the UK tt scene then use the big ring and a middle cog and stick with it for FTP test and sessions. If you mountain bike or climb a lot in road races stick to the small ring and a middle cog. Whatever - pick one gear and stick with it…maybe change up or down one cog at the back in between training blocks to avoid wearing out one cog