Lies, Damn Lies, and Bias

Josh, Hottie, and Fatty talk about problems in data quality, sampling bias, confirmation bias, cherry-picking, and more (including a little detour into baseball). it’s great when data bolsters your beliefs or arguments, but it’s oftentimes way more exciting and enlightening when they don’t!

Got a question you’d like to ask? Text or leave a voicemail at the Marginal Gains Hotline: +1-317-343-4506 or just leave a comment in this post!

Subscribe using your favorite podcast platform (but be sure to rate and review us on Apple Podcasts).


  • Robert Jacobs

    Is it faster to shift up through the gears from a stop, or just leave the bike in a high gear and grunt it out until up to speed? Which method causes more wear on the drivetrain? Also for all the discussion and angst about tire pressure, I am wondering if there is a preferred tire pressure gauge that is both precise and accurate.


  • Michael Brooks

    Isn’t the foundation of science that someone comes up with a hypothesis and then we experiment to prove or disprove it?

    Anyway a question for Josh, I understand that a disc wheel can produce a sail effect at certain yaw angles, If I would like to go as fast as possible in a straight line Am I better of with a tailwind directly behind me or at an angle for a better yaw angle? Or again does it depend?

  • robbie morris

    first of all i want to say what a huge fan of your work i am. You have inspired me to search for marginal gains in every form of racing/riding that i do and i hope you continue to share your wisdom and insight with us less “engineering” type folk….my question is this if you dont mind me asking.

    so its time to replace the bearings in my mavic wheels and i want to go with a quality/low friction non ceramic bearing…. would i benefit from a angular contact bearing or are the quality radial bearings just as good for wheels…..if it matters im about 170 lbs and lucky to break 1400 watts in a sprint….thanks for any help and advice. I look forward to hearing your response

  • Jeff Dieffenbach

    Here’s an AJA question stemming from this Silca YouTube video on chain cleaning: (perhaps they’ll be answered in Part 2?)

    1. Is the chain cleaning Josh showed something to do just before waxing a chain, or also wet lubing?

    2. How often should this cleaning be done? In the case of waxing, it sounded like relatively infrequently.

    Some elaboration:

    - When I’m riding dirt, I might clean my chain every 4-5 rides depending on conditions—would this approach be used that frequently?

    - The process seems to go through a fair bit of degreaser and acetone—that may be great for a clean chain, but not so good for the wallet and the environment. When I clean my chain, I’m going through just a few ounces of degreaser in the Park Tool CG-2.4 chain cleaner. I’m sure I’m leaving all the dirt behind that Josh showed, and therefore giving up some watts, but I can replace the chain relatively frequently and still get a lot of life out of the rings and cogs.

  • Jon Dansie

    Question for the next AJA:

    What is known about the effect of wet roads on rolling resistance? I found some data from automotive tyres showing that the resistance increases. The authors theorised it was partly from hydroplaning impacts, and partly from the water cooling the tyre, hence increasing hysteretic loses. I would guess that the second effect impacts bike tyres similarly, but I’m leads sure on the first effect.

    Really love the show!

Leave a comment

Please note, comments must be approved before they are published

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.