Drivetrain Losses

[Splash]

What are all the possible drivetrain losses possible in the 11 speed SR Campag drivetrain?

What is the best mitigation to minimise each of these derivation losses?

Splash

[Louis]

https://www.google.com/?gws_rd=ssl#q=bicycle+drivetrain+losses

[stephenmarklay]

I was wondering the same thing today but more on the rotating mass of shoes, pedals, cranks, chain, sprockets etc. I am sure lightening these items would have some impact but I am not sure how much.

[Louis]

I was wondering the same thing today but more on the rotating mass of shoes, pedals, cranks, chain, sprockets etc. I am sure lightening these items would have some impact but I am not sure how much.

Assuming we aren't talking about lifting it all up to the top of a hill (in which case, mass is mass) I'd think of it in terms of moment of inertia and angular acceleration.

https://en.wikipedia.org/?title=Angular_acceleration

Of course the translational inertia of your body dwarfs the rotating stuff.

[Splash]

...mainly itnerested in the mechanical drive components such as chain, sprockets, wheels, cranks, etc...


SPlash

[stephenmarklay]

Assuming we aren't talking about lifting it all up to the top of a hill (in which case, mass is mass) I'd think of it in terms of moment of inertia and angular acceleration.

https://en.wikipedia.org/?title=Angular_acceleration

Of course the translational inertia of your body dwarfs the rotating stuff.

I was just reading joe freil's newer book Fast after 50 and he sites 1-2% loss per 100 gram in shoe weight for running. Made me wonder.

[Splash]

that sounds interesting...

Yes - could be onto something...would more weight applied onto the pedal generate power loss?


SPlash

[Peter P.]

Friction In The Power Transmission System

"Gear train and bearing losses with a well oiled chain absorb only 3%-5% of the power input. Because this is truly a minor factor affecting cycle speed, the chances for improvement are small compared to overcoming other losses. The cycle drive system is mechanically simple and efficient."

-Chester Kyle

From "The Science of Cycling"

[Louis]

Because this is truly a minor factor affecting cycle speed, the chances for improvement are small compared to overcoming other losses. The cycle drive system is mechanically simple and efficient.

Absolutely.

I almost replied to the original post with something like "work on reducing your aero drag instead."

[stephenmarklay]

Even if drivetrain loss is not significant I still wonder what saving say 1/2 pound or more in rotating mass equates too.

[Louis]

Even if drivetrain loss is not significant I still wonder what saving say 1/2 pound or more in rotating mass equates too.

Try it and let us know. (easy enough to add a few weights to your wheels)

[kramnnim]

http://www.friction-facts.com/

[cmg]

"The hub/wheel efficiency tester measures the friction created in the hub bearings. Accuracy is +/- 0.05 watts"

If you can fiqure out how to keep the ratching hub shell from making contact with the freehub while still ratching you can gain .05 watts.........

ever seen the rear bearings self destruct because the previous owner thought he could reduce seal friction by removing the seals? bad idea, but when the rear hub locks up you'll know somethings wrong.

no, i don't worry about drivetrain losses.

[bikinchris]

What are all the possible drivetrain losses possible in the 11 speed SR Campag drivetrain?

What is the best mitigation to minimise each of these derivation losses?

Splash

You are by far the least efficient thing on that bike. Work on your fitness, aerobic capacity etc. and technique. Once you are at the top professional level, (in other words, after about 8 years of training year round) then this might make a .05% difference in your speed.

[oldpotatoe]

Even if drivetrain loss is not significant I still wonder what saving say 1/2 pound or more in rotating mass equates too.

The so called 'fly wheel effect' is lost in the noise. Double the weight of a rim and the increased energy to spin it to a certain speed is something like .1 of 1%. So a 450 gram rim vs a 400 gram rim..well, it means nada.

As for 'drivetrain efficiency', a chain driven drivetrain is very efficient. Keep pedals, hubs, BBs, chain clean, adjusted, lubricated and it will not slow you down.

BUT 'cycling performance' is really 4 things, all starting with 'F'.

-fat-lackthereof on you
-fitness-being fit
-fit-bike fit, does your bike fit?
-finesse-riding, racing, training smart.

On a well fitting, well maintained $1500 bike, where you satisfy the above..you will be faster than not following the above even if your bike is $10k+

[mcteague]

What are all the possible drivetrain losses possible in the 11 speed SR Campag drivetrain?

What is the best mitigation to minimise each of these derivation losses?

Splash

Seriously? Do you really think this makes are real difference in your overall speed? :rolleyes:

Tim

[Black Dog]

You could be wearing steel shoes and it will not make a difference because they are attached to each other. Their mass cancels out. As you increase your leg speed there will be more inertia to over come. Once at speed no difference. If anything you will get a bit of a fly wheel effect that can smooth out your pedal stroke. As for friction there is not much more you can do with a super record drive train. Use wax on your chain. You will still not notice the extra watt.

[soulspinner]

you are by far the least efficient thing on that bike. Work on your fitness, aerobic capacity etc. And technique. Once you are at the top professional level, (in other words, after about 8 years of training year round) then this might make a .05% difference in your speed.

+100

[stephenmarklay]

You could be wearing steel shoes and it will not make a difference because they are attached to each other. Their mass cancels out. As you increase your leg speed there will be more inertia to over come. Once at speed no difference. If anything you will get a bit of a fly wheel effect that can smooth out your pedal stroke. As for friction there is not much more you can do with a super record drive train. Use wax on your chain. You will still not notice the extra watt.


Hmm. So you put on 100 pound shoes and I will wear 1 pound shoes and lets race from a stop.

[stephenmarklay]

Try it and let us know. (easy enough to add a few weights to your wheels)

It certainly feels different on heavy wheels vs light wheels as far as small accelerations and I imagine it would impact performance to some degree depending on terrain. A flat TT course not so much perhaps. A constantly undulating terrain I would guess more so.

[Splash]

Thanks Guys,

I read often that PT hubs present watt readings that are generally 2-3% less than watts measured at the crank - due to losses in the drivetrain.


SPlash

[laupsi]

Seriously? Do you really think this makes are real difference in your overall speed? :rolleyes:

Tim

agreed, sometimes some of the forumites spend way too much time over analyzing silly nuances instead of just getting out and riding their bikes. Oh and Happy Father's Day!

[shovelhd]

I'm wondering if Splash is a bot. :)

Fitness
Fit
Pedaling efficiency
Aero equipment
Everything else

[stephenmarklay]

The so called 'fly wheel effect' is lost in the noise. Double the weight of a rim and the increased energy to spin it to a certain speed is something like .1 of 1%. So a 450 gram rim vs a 400 gram rim..well, it means nada.

As for 'drivetrain efficiency', a chain driven drivetrain is very efficient. Keep pedals, hubs, BBs, chain clean, adjusted, lubricated and it will not slow you down.

BUT 'cycling performance' is really 4 things, all starting with 'F'.

-fat-lackthereof on you
-fitness-being fit
-fit-bike fit, does your bike fit?
-finesse-riding, racing, training smart.

On a well fitting, well maintained $1500 bike, where you satisfy the above..you will be faster than not following the above even if your bike is $10k+

Thanks! I guess I would add A for Aero but you might squeeze it into fit…

Also fit is perhaps overlooked. Yesterday I rode and ended up with a back spasm and guess what? I slowed down.

[Black Dog]

Hmm. So you put on 100 pound shoes and I will wear 1 pound shoes and lets race from a stop.

Hmmm. Read my post again. I mentioned that there is inertia to overcome and once your legs are spinning there is no difference. :rolleyes:

[cmg]

thread drift warning

"Double the weight of a rim and the increased energy to spin it to a certain speed is something like .1 of 1%. So a 450 gram rim vs a 400 gram rim..well, it means nada." i don't doubt this true but the flywheel effect will be short lived. your always either accelerating or de-accelerating it's rarely constant.

easy experiment. get a set of conti supersonic inner tubes (55gs ea.) and ride for a week. then replace them with thorn resistant tubes (100gs ea.) do you notice the difference? give it a try.

[Dead Man]

OP must have happened across the phrase "aggregation of marginal gains."

Or... Maybe the OP works for Sky

[mcteague]

agreed, sometimes some of the forumites spend way too much time over analyzing silly nuances instead of just getting out and riding their bikes. Oh and Happy Father's Day!

As Eddy is claimed to have said "don't buy upgrades, ride up grades". Painful but true if you want to improve.

Tim

[shovelhd]

Thanks Guys,

I read often that PT hubs present watt readings that are generally 2-3% less than watts measured at the crank - due to losses in the drivetrain.


SPlash

That's true, however it's something that you accept. Consistency is more important than absolute accuracy.

[oldpotatoe]

thread drift warning

"Double the weight of a rim and the increased energy to spin it to a certain speed is something like .1 of 1%. So a 450 gram rim vs a 400 gram rim..well, it means nada." i don't doubt this true but the flywheel effect will be short lived. your always either accelerating or de-accelerating it's rarely constant.

easy experiment. get a set of conti supersonic inner tubes (55gs ea.) and ride for a week. then replace them with thorn resistant tubes (100gs ea.) do you notice the difference? give it a try.

But it's not the weight, it's a big hunk of rubber in the tire and how it reacts to the ground.