What it is
Grouping lets you cluster multiple segments that share similar characteristics (e.g., “Flat with headwind”, “False-flat climb”, “Steep descent”) so they share one power target in optimizations. You can also think of it as an execution layer on top of segmentation: segments are the physics resolution; groups are the race-plan resolution.
Why it matters
Simpler race plan: fewer targets to remember → better execution on race day.
Intentional trade-off: you sacrifice a little theoretical optimality for a plan you can actually ride.
Technical limitation: There is a hard limit (20) to the numbers of power targets you can optimize. So if you have more than 20 segments, you need to group them or fix the power for some of them.
Where it lives
Grouping is defined inside an optimization (pacing or equipment), not in your course definition. You can try different groupings across versions without changing the underlying course.
How it interacts with the model
Optimized groups: leave a group set to “will be optimized” and the solver finds one target for all its segments.
Manual power (group): fix a group to a specific wattage to exclude it from optimization (by toggle the group power on).
Manual power (segment): a single segment can be fixed when it's not part of a group; toggle the manual power on and that segment won’t be changed by the solver.
When to group
After you’re happy with basic segmentation and wind (forecast updated), apply grouping to collapse the plan to meaningful buckets.
Regroup for different race contexts (e.g., windy vs calm) and save the results as versions.
Good patterns
Terrain-driven: Steep climb, Climb, False flat climb, False flat descent, Descent, Steep descent (this is what is done automatically).
Wind-aware flats: split flats by exposure: Flat with headwind, Flat windless, Flat with tailwind (this is what is done automatically).
Surface-driven sections: where Rough surface warrants distinct targets. This requires custom groups which is not available for all subscription plans.
Tips & pitfalls
Re-check that wind is up to date before grouping—changing segments requires a forecast refresh.
Avoid over-grouping huge mixed sections; keep groups internally consistent (terrain + wind + surface).
Remember: reapplying automatic segmentation later can overwrite manual segment edits; regroup after segmentation is final.
Example workflow
Load/trim/segment course → update forecast.
Apply default grouping for entire course.
Leave most groups optimized; fix manual power only where you must (e.g., neutral zones).
Run, review, and iterate with versions for different grouping ideas.