Andre,
For some years, the "Friction Facts" website published a series of reports on the friction levels of various components and lubes based on empirical testing; they were available for individual purchase and I bought most of them. Here is a little background on the former FF site:
https://www.cyclingnews.com/features/friction-facts-measuring-drivetrain-efficiency/The old FF site is still available through the Internet Wayback Machine here:
https://web.archive.org/web/20160307123619/http://www.friction-facts.com:80/test-results/individual-reportsAlmost two years ago, the FrictionFacts site was sold to CeramicSpeed, makers of low-drag bearing assemblies and components containing the bearings
https://www.ceramicspeed.com/en/cycling/The old FF technical reports are still available on the new CS website, now free of charge:
https://www.ceramicspeed.com/en/cycling/inside/test-data-reports/Per Pavel's observations, I think you will find this report interesting:
https://www.ceramicspeed.com/media/3502/cross-chaining-and-ring-size-report.pdfSome of their observations are surprising on the face of it but make sense on further reflection. For example, in...
https://www.ceramicspeed.com/media/3494/bearing-lube-seals-full-report.pdf...one of my favorite assembly and wet-weather lubes, Phil Tenacious Oil, was one of the least efficient
bearing lubricants, with among the highest average frictional losses in the test group making it seem a poor choice -- except in wet weather, where its relatively high viscosity clings like grim death to my chain. In adverse conditions, an exposed lubed chain has less friction than one whose lubrication has been washed away by road splash and rain...but that is for chains, not bearings and especially not for shielded chains or bearings. As you read the reports, you'll become aware of methodological limitations (a "drop" of lube is not equal across all lubes due to variations in viscosity and may result in comparative under- or overfill of a given bearing set or type resulting in secondary losses due to things like bearing "churn") and that a given lubricant's efficacy is very much a matter of horses for courses and whether or not friction reduction is primary or secondary to other goals like lubrication life or waterproofness. Factors like ball diameter (a Big factor when paired with various viscosities of lubricant), ball count, type and tolerance of seals (if any) and bearing design (i.e. cup-and-cone versus deep-groove Conrad-style cartridge bearings with various seals) all affect friction. As a result the same lubricant can have relatively low efficiency with some bearing combinations and much higher efficiency in others. Hub and bottom brackets have different requirements than chain rollers.
=====
I still have some older cup-and-cone hubs (Campagnolo Record, old Shimano 600, SunTour Superbe non-Pro, Sunshine/Sanshin Pro-Am) with holes factory-drilled in the center of the hub shell, covered by spring-steel clips. The idea being to grease the hubs for road use but to replace the grease with oil applied via the central clip-covered port for occasions where minimum friction was desirable -- things like Keirin racing (a Japanese 2km indoor track cycling event designed particularly for parimutuel betting) and hour-record attempts back in the day. I used such hubs for touring and commuting throughout the late '70s and early '80s. They were unsealed (I would sometimes wrap grease-soaked pipe cleaners in a spiral around the bearing dust caps for a modicum of weather sealing on commutes and wet tours), so I would occasionally use the oil ports to flush the hub with fresh, thick oil midway on particularly wet tours; it flushed any water or contaminants from the inside-out. The oiling ports worked well for that but I never noticed any difference in wheel friction in my touring use as there were too many other factors that muddied those waters -- things like rough roads and potholes.
Another site to view is ZeroFriction Cycling:
https://zerofrictioncycling.com.au/ They have a little different take on things geared toward sales but with some interesting FAQs and observations as well.
A couple addenda:
1) Like my Nomad with Rohloff, my Fixie has a perfectly straight chainline but no gearbox of any kind, no idler or tensioner, nothing but the chain, chainring and fixed sprocket. When properly lubed it is absolutely silent to my ears while riding and I have to be careful to ring my bell as I close on pedestrians who simply don't hear my approach otherwise. The gears last a long time, the chain less so because it has to resist not only forward pedaling forces but also rearward ones as momentum carries my legs through the top- and bottom dead-centers and as I apply rearward force to avoid excessive downhill speeds and to aid rim braking.
2) My randonneur (long distance day ride) bikes are setup with half-step and granny gearing, the chainlines offset toward the centerlines of the bikes and the most frequently used (cruising) gear combinations chosen to run with minimal deflection and so minimal friction; my favorites run in a straight line like my Fixie. As a result, drivetrain noise is minimal and with deliberately chosen large-diameter gears, component life has proven to be phenomenal compared to my derailleur bikes with crossover gearing that often runs at larger chain-deflection angles. Although the physically larger components are heavier (and being older and mostly non-indexed, also thicker), their reduced friction is noticeable and works nicely to offset the added weight as lifespan is increased. Larger derailleur pulleys help a lot too, minimizing the angles the chain must wrap around the rear derailleur's jockey and tension pulleys. Half-step gearing also means I have more usable gear combinations than I do on my bikes with crossover gearing and the gears are more readily available to me with less complicated shifting (13 usable out of 15 possible combinations for a 3x5 half-step discounting duplicates and excessive cross-chaining, 15/18 for a 3x6, and 18/21 for a 3x7 versus "only" 15/27 for my 3x9 crossover setup). For fun, I am currently setting up a go-fast bike with a 1x10, but the chainline deflection looks so scary in all but a couple combos, I am inclined to abandon the project and return to something more favorable.
Best,
Dan.
