Rubberbanding Power Question

I was just on a rubberbanding group ride and I gather from other threads on this topic that any PR on the route probably isn’t real, so my question is whether the average watts that I put out according to Strava is accurate? The group was a good bit stronger than I am and I struggled some of the time to stay in the midst of the pack, so I do think that I was putting out more watts than usual, but I don’t want to get all excited about an improvement that is not really there.

I have found the only sure way to know my output (other than expensive power meters) is to ride a known route as a time trial so there isn’t any drafting checking things. Or rerun the FTP test.


Yes, although your speed might have been artificially boosted by the “keep together” function, if it’s showing more watts then you did work harder than usual.

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I don’t think the rubberband changes your watts, just adjusts your speed.

I found rubberbinding in a strong group really taxing since when you’re trying to catch up with the front, your assistance is decreased but the stronger people in the front are held back less!

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Thanks, @Richard_Freeth, that’s a good idea - when I finish my FTP Builder training I will ride some of these routes again by myself and see where I end up. I’m on week 5 of 6 so I guess I will also be doing an FTP test in just a couple of weeks. There doesn’t look like there is one embedded in the plan, so I guess I’ll just rest up for a day or so at the end and do one.@Steve_Hammatt, thanks, that is what I am hoping :grinning:!
@Nicklas_Karlsson, I’m glad you wrote that. I had some technical difficulties (everything paired fine and looked good, but when I was transferred to the course it was as if everything had been unpaired - zeros across the board), and when I finally got in with everything working the feature that joins me with the group plopped me on the course within sight of the group, but way behind. I cycled like a madwoman trying to catch them. I must have eventually gotten close enough the the rubberbanding pulled me into the group. But, as you say, even then it sometimes felt hard to keep up. Interestingly though, the group leader had a technical glitch and popped out and then back in way behind the group, and when I slowed down thinking I would drop off the back and see whether I could have a team effort to get him back with the pack, I couldn’t drop off the back. Now I wonder whether I needed to just stop pedaling entirely. Not that I am a tech saavy person, but I do wonder how the rubberbanding algorithm works.
P.S. Sorry about all the individual responses. I now see the note that says not to do that. I’ll put them all in here and see if I can delete the others. Hope this works!

My guess is that algorithm is something like

“Sum all mass and all power output of the group and determine where the center of the group is and what speed does does point move at. Then adjust the speeds proportionally to the distance from that point to assist/hinder the person”.

Given that, if everyone would manage to keep their power level exactly, the would (on a flat road), gravitate towards that point. Of course, since nobody can keep their power output, the destination point keeps moving and, well, rubberbanding :wink:

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