Drive Train Efficiency

rudabagle

Like most, I am extremely unimpressed with everything bicycle buying guides. I feel like 99% of these "guides" are purely anecdotal and use no reliable testing methods to obtain objective results. Others have posted about friction-facts.com, which came into the lime light after VeloNews featured an article looking at chain lubes.

I thought Eureka! Finally, an objective review of cycling components. So like any good interneter, I tried to find a free copy of the friction-facts reports, but failed. I finally spent the 15 dollars to read more about the methods, results and interpretations for drive train components. My big take away surrounds these major parts, the chain, the chain lube, the derailleur pulleys, and the bottom bracket.

I have been "waxing" my chain for quit some time and (beware another anecdote) I can not stop recommending this to others. Even if there is not a watt benefit, the benefit of always having a clean (i.e. not black and oily) is the best.

In my next step to improve my component selection using objective data, I decided to upgrade the bottom bracket. Friction facts tested several BBs. Not every standard, nor manufacturer, but their biggest takeaway message was the quality of the bearing used in the BB have the strongest association with minimal friction loss, that is ceramic and steel bearings of equivalent "roundness" (or how close to a perfect sphere are they) will have the same coefficient of friction, or the same energy loss to friction. Ot the top 3 performing bottom brackets I choose the C-bear brand. http://www.c-bear.com/

I recently upgraded my frame to the Bianchi Oltre XR.2. The Oltre uses the 386evo BB standard. Now, friction-facts didn't test this standard and I am extrapolating from the reports take home message, bearing perfection is the main factor contributing to performance. I made a video showing the installation of the BB on Youtube. https://www.youtube.com/watch?v=ZZ0Rimpk1oo

My initial impression is positive. I replaced a "wheels manufacturing" BB. When applying a similar force the C-bear BB seems to spin one or more revolutions than the wheels manufacturing. Again, another anecdote and hard for me to tell if there is any perceived advantage (but when we are talking about 1-2 watts, you really would only notice these savings over many miles).

Thanks for reading and let me know if you have any questions.

Greg

imposter2.0

My question is - What on earth are you talking about?

6wheels

Better balls mean less friction!

slam that stem

What is he talking about? See the you tube video of Cancellara meditating in the starthouse before the TT Worlds a couple years back. Almost in a trance, he get up, steps over to his bike and spins the cranks backwards. They continue to spin for 3-4 revolutions. Amazing! Bikes never do that. Oftentimes, a bare crank barely does that.

Don't worry about quantifying savings. If you make a change to a component and you feel it spins easier afterwards that's all the proof you need. Try counting how many revolutions your bare cranks make before and after.

For another BB option, Prototype.pt is good. I have one of their BBs on my Cervelo and it's very smooth. They opted for very round, expensive steel balls rather than the ceramic approach. http://www.prototype.pt/product/bb-pressfit-41

I've read a lot on this as well and was left with a few principles: 1) bearing roundness is more important for bike applications than the material. Better to source the roundest quality of bearing than worry about ceramic vs. steel 2) do not overgrease, 3) avoid components with bearing spacers/holders, 4) remove contact seals where possible, 5) cone/cup allows for better fine tuning of play than cartridge, 6) alignment is crucial but difficult to remedy on carbon bikes or non-threaded BBs. You don't see shops reaming non-metal BBs or facing integrated head tubes.

I'd recommend your next culprit be the rear mech. The Berner solution is a good one. If you run Shimano/Sram there are also 12T pulleys you can buy - but careful of clearance, esp. on the top. And some argue that forcing the chain to bend more as it transitions from the larger diameter top pulley to the larger bottom robs energy.

The big "Italian secret" from the early 2000s which Contador's brother later tapped into was Gold Race and it turns out they're still around: http://www.cecchiniteam.it/ They do (I'll not say 'make') a chain but I wonder if it's just a treatment rather than a design. In biking applications which are dirty, treatments to a moving surface eventually wear off. They all do. Except maybe the plunger on a Fox rear suspension unit.

After you've done all you can with bearings you can move onto tyre rolling resistance, lots to read on that. Then after that aerodynamics.

imposter2.0

And when you've done all that, you can work on your fitness...

cycleclinic

You would be surprised how little power is actually consumed by BB, chains e.t.c. Changing bits for smoother running ones may save nothing or a small fraction of a % it is not exactly the first thing you do as getting a bit fitter makes a bigger difference.

Also the smoothest running BB's are square taper's. Didn't fit one of those did you? I am not faster however on a square taper BB compared to an external BB.

That article is selling you an empty wallet. Will you actually enjoy a ride any more now than before. Just ride and stop chasing the most marginal or marginal gains.

earthvspace4XTuUWcX

Team Sky might be interested in a 0.001% efficiency saving but it makes bugger all difference to me :roll:

taon24

Easiest way to reduce the friction losses of a BB is to remove all forms of sealing. Unfortunately this means more muck getting in and either cleaning or the bike getting cleaned (Cancellara) after each use or accepting a loss of bearing performance, beyond the losses involved in the sealing, due to build up of gunk. You'll probably pay more in replacement bearings more frequently. Personally I'd go for a cheapish BB for less than GBP 15 and replace as needed.

rudabagle

@imposter -- Correct, fitness is the best way we amature racers/riders can improve our performance. I agree with you 100%. However, my main point still stands: really nothing out there gives a 3rd party objective review of bicycle components. When I found the friction-facts website, it was a big relief.

@taon24 -- Correct. In fact, friction facts top performing BB was not sealed. The Gold Race BB @slamthatstem mentioned was the top performing BB. Since I do not feel like cleaning my BB after every ride, I opted for the sealed option.

@thecyclingclinic and @xdoc -- So you are kinda correct, in this example the c-bear BB consumes .3 watts of 250 watts, while the dura ace BB consumes 1.5 watts of 250 watts. While 1.5v watts only represents 0.6% of your 250 watts being lost to friction, the improvement from dura ace to the c-bear option is an 80% increase in efficiency and changes your watt loss to friction to only 0.1% of 250 watts. This may not be significant over the course of 30 minutes, but it certainly adds up over the course of a 4 hour race. Now, the article is not selling me anything. I purchased the article to understand which components are better than others. I merely used it to make an informed purchasing decision. Of the top performing BB, the c-bear was the cheapest at 130 us dollars, which compared to the total cost of my bike is peanuts. Now, had I gone with Hawk racing or Ceramic Speed, their BBs cost upwards of 350 us dollars. Clearly, I chose the option with the best quality to price ratio as I also don't like an empty wallet but I also prefer to buy true quality over "brand" quality. But I agree, a lot of this stuff is a wallet burner and I would not recommended it for the weekend warrior, but for amature racers, IMO, I would.

@slamthatstem -- So my next step is the rear derailleur pulleys. Friction-facts also tested this out. The top performing pulley system was the Berner system, saving you on average compared to the DA system 1.3 watts. Now this is great, but the cost to upgrade to the Berner system is a little more significant than the c-bear bottom bracket. I think their system costs around 270-360 euros. That is a little steep for just 1.3 watts of savings. But maybe i will have some fun and purchase the upgrade.

I will report back with a couple of updates regarding the BB performance (all anecdotal and probably biased to my hopes, but the placebo effect is a real thing and like @slamthatstem says, if it feels better that is all that matters), but for now, I took her out for a hard ride this weekend and was quite pleased. I know my opinion is extremely bias but it did feel better than the previous BB, my pedal strokes just seemed very calm and fluid. No noise, no weird vibration, just solid stroke after stroke hammering home.

meanredspider

Given the obsession with weight in this sport (where 50g represents less than 0.1% of the total system mass and, I'm sure, quite a bit less in overall energy requirement), I don't think it's unreasonable to look at parasitic losses.

bompington

rudabagle wrote:

... placebo ...

MountainMonster

OK, so that is what the labs say.

What is the difference to cycling in the real world? All this research surely must make a big difference?

earth

@ rudabagle

Don't worry the cavalry is here


While I was giving the bike a good clean I decided to change the jockey wheels as they were a bit worn and chewed up. I decided while I was at it I might look into ceramic bearing wheels. So I went looking for reviews and found the friction facts site. I paid for the results and it was enlightening. The Tacx ceramic wheels had the third least friction but are about the same price as Shimano steel bearing ones. Absolute best price/performance and I got them for a bargain price as well. The difference may only be small but I paid no more than standard ones so why not?

I have also been trying waxed chains with mixed results. On the fun bike I am getting about 300 miles out of a waxed chain before it need rewaxing. During those 300 miles it is smooth and silent and totally clean. Nothing sticks to it. Very impressive. It does take a bit longer to apply than normal lube but if I spend 20 mins every 300 miles then I'm not fussed. Wax is cheap. Friction Facts shows that the Purple Extreme lube I normally use is amongst the worst for friction and I can say from experience it does not last as long as wax.

On the commuting bike however it's a different story. I am lucky if I get 120 miles out of a chain before it gets noisy. So I have gone back to lube for now. I have spoken to Friction Facts about it and they put me onto the guy who makes molten speed wax. He was very helpful in suggestion how to clean the chain and apply the wax. The application is everything it seems and some chains might be a bit too tightly made to allow wax between the moving parts.

jgsi

What a load of old tosh... it's a bloody shop selling snake oil... and overpriced components.

rudabagle

@MontainMonster -- You are correct. The lab study has great internal validity. However, we can say nothing with regards to external validity or generalizability (are these results representative of the real world?). Nevertheless, it is a great start. My main point is that there are minimal entities providing objective reviews for the plethora of options we have. Being a researcher, I am not going to go on some marketing campaign or some anecdote from a rider. I was just expressing my experience using an objective, third party reviewer of bicycle components to inform my purchasing decision. The difference between the top performing brands is minimal, but the price varies significantly. I can not alone quantify my experience with the lab tested top product with any sort of authority, but as I describe, I perceived a difference and acknowledge it could be placebo, or related to my own bias (the lab said it was better so it must be better). Given that, the lowest level of authority would be expert testimonial (i am not). The next level could be a review of pro-riders, the components they use, and the results they obtain. Again higher authority, but the results would have significant limitations. Finally, if we could perform some sort of randomized controlled trial within the pro peloton, we may be able to draw real world conclusions.

@earth -- SWEET! I am a huge proponent for chain waxing. I too have had problems with my commuter bike and keeping the chain waxed for periods longer than 300 miles. I think you hit the nail on the head, my commuter is a SS with a wipperman chain. Maybe the bigger width chain needs to be waxed more frequently? RE the 20 min time commitment: Another method that you may want to consider is purchasing 6 chains and waxing them all at once, for a 20 minute wax job you would potentially get about 1800 miles. In the end, you would be looking at about 3-4 wax jobs a year (also if you start with new chains and new cassette and chain rings you would extend the life of all the components)

rudabagle

@JGSI -- unfortunately, friction-facts is not a shop, and they are not really selling anything besides information. Second, their reco regarding chain lube is paraffin wax, the cheapest of cheap. But you are right, for someone who can only produce 216 watts for an hour (http://www.trainerroad.com/career/jgsi), these marginal gains mean nothing. @imposter's comment was spot on, you need to work on your fitness...

earth

The price of the Friction Facts test results are little more than the price of a couple of monthly magazines. The reviews in those are rarely worth anything. I couldn't even describe some of them as reviews - a photo, a description of the product and few stars beneath.

For the about the same price from Friction Facts you get the results of objective tests. I see a wider market for this.

jgsi

rudabagle wrote:

@JGSI -- unfortunately, friction-facts is not a shop, and they are not really selling anything besides information. Second, their reco regarding chain lube is paraffin wax, the cheapest of cheap. But you are right, for someone who can only produce 216 watts for an hour (http://www.trainerroad.com/career/jgsi), these marginal gains mean nothing. @imposter's comment was spot on, you need to work on your fitness...

you are most welcome to make yourself known to me at the Shropshire rounds of reliability rides in February.. after 40 miles at a certain pace , the last thing on your mind will be friction facts , mate.

rudabagle

@JGSI -- Well, since we are not even on the same continent, it seems unlikely. Also why so vague with your challenge? What is this certain pace you talk of? I had no intention to be rude or point your current performance (in)abilities, but you obviously came out swinging. So I will continue down this road, as bullies suck and should be put into their place. The terrain you routinely train on is, flat. Not so hard a task to push out 18mph for 50 miles with only 990 ft of elevation gain. What exactly do you feel is a competitive pace for such a stroll? It is understandable that you are feeling strong, with your recent 30+ PRs, and picking fights with this new found sense of confidence is exactly what bullies do. Regardless, if I am ever racing in the UK or you decide to race in the Northeast US, I would welcome a meeting and civil discussion on the topic. I have nothing to hide (you can find my information as easily as I found yours). Then after the dust settles, we can go for a ride, at a certain pace of course !

Again, the main message in this post, we need more objective reviews for cycling equipment, @earth agrees too.

Finally, What is on my mind during races or hard sessions at a certain pace? I am always looking for an edge, friction-facts is definitely an edge. Rather than horde the information, I decided to share my experience using it with fellow cyclists, and as expected a couple of trolls came out to play, all good, it is the internet afterall.

Finesilver24

rudabagle wrote:

@JGSI --... But you are right, for someone who can only produce 216 watts for an hour (http://www.trainerroad.com/career/jgsi), these marginal gains mean nothing. @imposter's comment was spot on, you need to work on your fitness...

Epic come back!

However Greg, the question remains. What actual real-world difference would an average rider get if they changed, for example their entire set up to the the lowest possible friction parts available, how will this affect my FTP (316W recorded on a powertap)?

rudabagle

@finesilver -- Your FTP will not change. In this example if your FTP is 316 watts and your drive train consumes 10% (31 watts) of that energy into friction loss (ie heat and noise being generated within the drive train) then only 285 watts are available to propel you forward (overcoming other barriers to speed as well: aerodynamics, friction within your wheel hubs, rolling resistance from your tires, and your mass). If you could increase your drive train efficiency to 7% consumption (or 22 watts), then you would have 294 watts available to propel you forward, a 10 watt difference is not insignificant at your power threshold.

Does this make sense?

Finesilver24

rudabagle wrote:

@finesilver -- Your FTP will not change. In this example if your FTP is 316 watts and your drive train consumes 10% (31 watts) of that energy into friction loss (ie heat and noise being generated within the drive train) then only 285 watts are available to propel you forward (overcoming other barriers to speed as well: aerodynamics, friction within your wheel hubs, rolling resistance from your tires, and your mass). If you could increase your drive train efficiency to 7% consumption (or 22 watts), then you would have 294 watts available to propel you forward, a 10 watt difference is not insignificant at your power threshold.

Does this make sense?

Wow. I never realised a normal drive train consumed 10% of my power. I always assumed it was around 3-4%. Maybe I'll clean my chain and get a new PB on my local 10.

BTW, my mass is not a friction. My force accelerates my mass, and brakes remove the inertia through heat (and a little bit of noise) which is friction.

rudabagle

@finesilver24 -- I don't know if your drive train consumes that much, but the results from friction facts suggest a 4-6 watt savings when using a dura ace chain, lubed with paraffin wax compared to a dura ace chain lubed with a standard wet lube. Take that into combination with other drivetrain components maximized for efficiency, your BB, pedals, and pulley system, you can see a combined watt savings upwards of 20 watts (as compared to the poorer performing products, and surprisingly many of the big brand names were the worst performers, FSA, Shimano, SRAM)

Mass has a direct effect on the rolling resistance (a frictional force), so your rolling resistance force is influenced by your mass through the equation u*Fnorm = Force of Friction (u is the coefficient of friction and Fnorm is your mass times gravity at a given slope). The bigger your mass, the larger the force due to rolling resistance (especially uphill), but you're also correct, the remaining watts left over is the force used to accelerate your mass.

gloomyandy

Out of interest, what was the testing methodology used for these products? Were the bearings placed under real world loads (so wheel bearings with a realistic rider weight and power being applied etc.). I ask because I listened to an interview with Tim Mulrooney of HED and he claimed that in the tests that they ran, ceramic bearings showed an advantage when lightly loaded but that this pretty much disappeared when used with real world loads applied.

rudabagle

@gloomyandy -- Excellent question. Here is a review of the methodology used by friction-facts RE: Drive train efficeny: http://www.friction-facts.com/equipment/chain-full-load

They tried to mimic real world loads, ie cadence@95, 250Watt load, 53t chainring, etc..

HED's assessment regarding Ceramic vs. Steel is also correct, it is not the material, but the roundness or how closely the bearings are to a perfect sphere.

meanredspider

rudabagle wrote:

Mass has a direct effect on the rolling resistance (a frictional force), so your rolling resistance force is influenced by your mass through the equation u*Fnorm = Force of Friction (u is the coefficient of friction and Fnorm is your mass times gravity at a given slope). The bigger your mass, the larger the force due to rolling resistance (especially uphill), but you're also correct, the remaining watts left over is the force used to accelerate your mass.

I don't think this is correct. Take the bit I've emboldened for instance. Take this to the limit (vertical uphill) your mass becomes irrelevant to the rolling resistance because there's no reaction force in the rolling plane.

I also believe rolling resistance is far more complex than you describe too.

imposter2.0

Gravity beats rolling resistance uphill...

rudabagle

@meanredspider -- Absolutely, I was just representing it as simple as possible. Here is a better discussion of the topic:
http://en.wikipedia.org/wiki/Rolling_resistance

Still, the normal force of the mass plays a role.

rudabagle

Imposter wrote:

Gravity beats rolling resistance uphill...

Gravity always manifests itself as rolling resistance, regardless if you are going up of downhill. Please see previous post. Rolling resistance is the rolling resistance coefficient times the normal force of the rider. Normal force is gravity times weight times the cosine of the angle of the slope.

crikey

Have any of you people ever had sex with anyone other than yourselves?

rudabagle

crikey wrote:

Have any of you people ever had sex with anyone other than yourselves?

rudabagle wrote:

as expected a couple of trolls came out to play, all good, it is the internet afterall.