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PostPosted: Wed Jun 12, 2013 10:11 am 
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I'm not asking for results and will go buy it but does the pedal report include all pedals? I.E. I ride Time Xpresso 12, are they on there?

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PostPosted: Wed Jun 12, 2013 12:55 pm 
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Juanmoretime wrote:
I'm not asking for results and will go buy it but does the pedal report include all pedals? I.E. I ride Time Xpresso 12, are they on there?


Each report say's what is tested before you purchase.

Pedals tested are:

Crank Bros Eggbeater 3
Look Keo Blade Carbon
Mavic Race SL Ti
Shimano Ultregra
Speedplay Zero SS
Time I-Clic 2 Carbon


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Posted: Wed Jun 12, 2013 12:55 pm 


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PostPosted: Wed Jun 12, 2013 1:45 pm 
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deermatt wrote:
. I more so wanted to see it to pass the time, and i like facts, but cant see it being worth buying.


It's freakin' $5 for a report, $10 for the full suite: hopefully the time you spend reading it is worth more than that, or you're paid less than minimum.

And 2 watts is like saving 500 grams or more off your bike.

Trust me: it's worth the money.

I've got to get the pedal report.

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PostPosted: Wed Jun 12, 2013 2:59 pm 
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Clearly nothing is free the cost of the parts will cost :-). With the cost of the info being insignificant relatively speaking I love love to hear the bottom line results because that is where it counts. Start posting some results with clear measurable comparisons of individual performance then we can talks about it.
Loose 5 lb. and improve the way you train and that translates in to a lot more and it will be free.
Bring it! :twisted:

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PostPosted: Wed Jun 12, 2013 4:33 pm 
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The only problem is that he doesn't test parts after they're worn and seen the same conditions. When I wanted pulleys I got the pulley report to replace my worn SR jockey wheels. It won't give anything away, but SR weren't the best new, however, my friend's Hawk Racing pulleys spin a lot less smooth after use and the KCNC pulleys that were ranked better than SR are junk after a few months. So in the end I went SR knowing that they last, but the report doesn't capture that kind of stuff.

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PostPosted: Wed Jun 12, 2013 5:17 pm 
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Wow pulley jockey wheels wear?
Never replaced one before.

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PostPosted: Thu Jun 13, 2013 7:28 pm 
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KWalker wrote:
I bought them a few weeks ago. Altogether and with all the RR data out there it will hopefully help a client of mine save around 20-24w on his TT bike (pulleys, chain, tires, and glue job).


Open question here, as I'm just curious... I've always been told that at speed you spend about 90% of your effort on wind resistance (even a professor in a sports physics class at the university told me so when we talked about aerodynamics in sports), and then we talked about some 35km/h so fairly slow...

Let's just for the sake of argument say you still loose 90% to wind resistance at 45 km/h, some 450 watts or so, right? ...can you actually shave 24 watts out of those 45 watts (your 10% non-wind resistance)? It sounds so unlikely that you could easily cut all mechanical resistance in half?

Please enlighten me?

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PostPosted: Thu Jun 13, 2013 9:39 pm 
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On the wear side, don't confuse wear with contamination. Dirty pulleys have more resistance. FrictionFacts uses an ultrasonic degreasing step before each test, typically followed by a "wear-in" cycle which helps reduce friction from the initial installation, so the tests tend to be under fairly optimal conditions. One take-away message is more important than equipment choice is equipment condition. A pro rider would have his drivetrain completely cleaned and lubed before any event of any importance.

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PostPosted: Thu Jun 13, 2013 11:55 pm 
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DMF wrote:
KWalker wrote:
I bought them a few weeks ago. Altogether and with all the RR data out there it will hopefully help a client of mine save around 20-24w on his TT bike (pulleys, chain, tires, and glue job).


Open question here, as I'm just curious... I've always been told that at speed you spend about 90% of your effort on wind resistance (even a professor in a sports physics class at the university told me so when we talked about aerodynamics in sports), and then we talked about some 35km/h so fairly slow...

Let's just for the sake of argument say you still loose 90% to wind resistance at 45 km/h, some 450 watts or so, right? ...can you actually shave 24 watts out of those 45 watts (your 10% non-wind resistance)? It sounds so unlikely that you could easily cut all mechanical resistance in half?

Please enlighten me?


I cannot answer your question in the way you posed it but his position has been optimized using roll down tests as best we can.

RR data shows that a switch from his old tires to new tires should net around 12-15w depending on how good his glue job is.

The new chain should save another 6w.

Properly cleaned and lubricated spindles another 1-2w.

Jockey wheels we're unsure of.

So if he had not optimized those things he'd have that many more lost w in terms of friction and RR. Also changed his helmet, which helped in the roll down tests. If we want to believe Castelli his new skin suit should add something I've not included in these calculations.

So if you add it up for a pro:

Oversized pulleys: 2.4w
Optimized chain: 6w
Ceramic BB: 2w
Proper width tires with appropriate glue job: 12w

Simply covering these bases nets them 22.4w over competitors that do not do these things. It might not be this much in practice, but it makes sense as to why they bolt on Berner derailleurs on special days, re glue tires and match them to the rim width, and pursue such small gains.

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PostPosted: Fri Jun 14, 2013 6:35 am 
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Yes ofcourse I too believe in optimizing everything that can be optimized, it was just the numbers that seemed so out of line when put into context?

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PostPosted: Wed Jun 19, 2013 8:56 pm 
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Just adding this which references pulley size.

The difference from best (15-tooth) to worst (10-tooth) was very small but still measurable at just 0.49 watts – similar to what others have calculated on theoretical terms. Comparing the 15-tooth pulleys to the 11-tooth ones more commonly used in modern derailleurs, the difference drops to 0.25 watts. Smith contends that the larger 15-tooth pulleys require the chain links to articulate less than with smaller pulleys as they pass through the cage, thus generating less friction between the side plates.

Subbing in the standard manufacturer's bearings – but still maintaining constant lower chain tension – extends that difference further, says Smith. A standard Shimano Dura-Ace 11/11-tooth pair of pulleys takes 2.6 watts of power compared to 2 watts on Berner's ceramic-enhanced 13/15-tooth setup.

Cage tension also apparently plays a role. In general, less tension is better than more. Smith says a stock Shimano Dura-Ace pulley cage creates 14.19N (3.19lb) of lower chain tension whereas a Berner's more lightly sprung setup creates less than half at just 6.85N (1.54lb). Taking all three factors in total (pulley size, bearing performance and cage tension), Smith measured a difference of 1.76 watts.

An efficiency gain of less than two watts is hardly earth-shattering for everyday riders and hardly practical when you consider that a ceramic-equipped Berner cage assembly runs about €359 (about US$478 or £305 at straight conversion rates). Two watts is still two watts, however, and for top-end pro riders and teams that rely on race results for their livelihoods, it's relatively "free" speed.


http://www.cyclingnews.com/features/fri ... -efficient

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PostPosted: Thu Jun 20, 2013 1:03 am 
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The chain tension observation is particularly insightful. Less tension on the chain = less resistance to bend it as it travels through the pulleys and onto the rear cog.

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PostPosted: Wed Sep 10, 2014 10:57 am 
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Regarding pulley size, just adding to the comments here in relation to Berner derailer.

Three factors are identified in the report affecting efficiency: pulley size, pulley bearing friction, and tension.
WRT chain articulation, the response above states that the difference between 15t pulley pair and 11t pulley pair is just .25 watts.
That is not a lot.

Looking over a different report (Pulley Report), there is very little room for improvements to be offered by improving the pulley bearing. Even when considering that the Berner pulley rotates at a slower rate, there just isn't room for consequential improvement. (So the saying half of nothing is still nothing.) Thus, unless other factors are present, this means the vast majority of the Berner derailer efficiency is attributable to chain tension reduction. Chain tension can be reduced with low cost improvements.

Chain tension is determined by several factors: Tension spring, Derailer Cage Length, and Pulley Radius.
Firstly for tension spring I would think that something like Hooke's Law applies.
The law claims that the force needed to stretch a spring is proportionate to the length that the spring is pulled.
Thus the more stretched the spring, the more force required. The tension spring in the derailer is located on the derailer cage and instead
of being pulled, it rotates around the axis of the spring. Even though this doesn't fit into Hooke's Law paradyme, I would expect that the tension is proportionate to the amount of rotation or certainly more rotation requires more force. The response above provides constant numbers regarding the Berner and Shimano systems. Instead I would think the tension varies. When the chain is on the largest front and rear sprockets, the chain is shortest, the derailer is pulled tightest, and the tension is highest. This suggests that the length of the chain should be increased to the maximum allowed by the derailer system.

The cage length and radius of the pulley effects tension. The tension spring is located at the axis of rotation of the cage. A lever is formed between the axis and the point at which the chain meets the bottom pulley. Increasing the cage length or the radius of the pulley results in a longer lever. Making the lever longer increases the mechanical advantage of the lever system and thus reduces chain tension. (Note the chain needs to be lengthened to accomodate the longer lever.) Any contribution provided by using a larger pulley can instead be accomplished by using a smaller pulley with an even longer cage. Thus, a longer cage is preferred. This does not address any wind resistance issues caused by the longer cage.

Another advantage to using a longer cage is that the tension will be more uniform when shifting through all the gears. A longer cage has the ability to take up more chain slack with less rotation of the cage. With less rotation, the tension spring isn't stretched as much and so the tension remains more constant through all the gears.

Given the fact that most derailers use 11t pulleys, there are simple improvements that can be applied to existing derailers:
1. Lengthen the chain.
2. Where long cage options are offered, they would seem to be preferable.
3. After market longer cages could be offered for use with existing derailers. (They just bolt on!)
4. Aftermarket weaker springs could be offered for use with existing derailers. (Very simple to install!)

I am curious what the results would be for the following studies:

a) Comparison of the Dura Ace 7700 Long Cage 13T Derailer versus Berner. Also cheapy Shimano Altus M310 13/15T derailer (with bearings replaced as was done in the Friction Facts study).

b) Comparision of chain tension versus chain friction. The resulting graph might identify where diminishing returns occur for reducing tension. Here the assumption is that chain tension is desirable, perhaps for safety or for effective shifting operation.


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PostPosted: Wed Sep 10, 2014 11:07 pm 
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What about chain slop from having a de tensioned chain all the time?


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Posted: Wed Sep 10, 2014 11:07 pm 


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PostPosted: Fri Sep 12, 2014 12:05 am 
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KWalker wrote:
So if you add it up for a pro:

Oversized pulleys: 2.4w
Optimized chain: 6w
Ceramic BB: 2w
Proper width tires with appropriate glue job: 12w

Simply covering these bases nets them 22.4w


Aye, there's the rub. Does it really work out like that? What happens when you measure it in its original state, make all those changes at once and then re-measure?


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