I see that study entitled "Exogenous Ketosis Impairs 30-min Time-Trial Performance Independent of Bicarbonate Supplementation". It does not negate their earlier study.

Here's what the new study concluded: ketone ingestion impairs performance, and that taking bicarbonate along with ketones does not fix the problem.

Seriously, if you want to perform better on long efforts, skip the ketones and eat more carbs.

Also, I can find no evidence that "all the pros" are downing ketones. Several teams have experimented with them, but most of them have abandoned their use, citing lack of results. On the other hand, every pro team is downing massive quantities of carbs.

Edit: This ketones/bicarbonate/carbs discussion is off topic. Maybe we can keep this thread about training for efficiency, thanks.