# Berner oversized derailleur pulleys - has any one tried them?



## natedg200202 (Sep 2, 2008)

I'm noticing more and more pros are using these aftermarket derailleur pulleys that are larger in diameter. Supposedly, they reduce the tight bends in the chain and reduce drivetrain losses. 

Has anyone tried them? Any noticeable difference in smoothness or shifting?





































Then you have this custom monster that was spotted on LA's bike at the Prologue:


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## Ventruck (Mar 9, 2009)

Never tired them, and there is logic behind that design, but pulleys don't play that big of a role in drivetrain power loss.

I wouldn't buy into it. Even ball-bearing pulleys can be considered overkill.


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## MR_GRUMPY (Aug 21, 2002)

Anytime you see "new" things on a Pros bike, you can be assured that they were paid to put them on.


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## natedg200202 (Sep 2, 2008)

Oh, I see. So the tiny company that makes these aftermarket pulleys is paying them to ride them? I wonder what their component sponsors (SRAM, Shimano) think about this.


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## Ventruck (Mar 9, 2009)

natedg200202 said:


> Oh, I see. So the tiny company that makes these aftermarket pulleys is paying them to ride them? I wonder what their component sponsors (SRAM, Shimano) think about this.



Only time Shimano utilizes and notes an over-sized pulley is with their Acera derailleur. 13t on the lower pulley. That _might_ imply something.


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## SilverStar (Jan 21, 2008)

Ha...when I saw these Berner pulleys I immediately thought of the cheapie Shimano derailleurs installed on "box store bikes"...maybe all those Wal-Mart Warriors were onto something before the pros?!?


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## ericm979 (Jun 26, 2005)

Ventruck said:


> Only time Shimano utilizes and notes an over-sized pulley is with their Acera derailleur. 13t on the lower pulley. That _might_ imply something.



They used 13t upper and lower on the 7700GS.

Those derailleurs work well (I have a couple) but I can't say that they are better than standard pulleys.


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## gamara (May 20, 2002)

Another pro fad that might or might not stay around. Remember those cinelli spincaci add on bar extensions that everyone was using at one time?? Sure they were aero but then all those nasty crashes happened because of them. 

As far as the Berner pulleys are concerned, the pro's are paying for all this stuff on their own because as another poster noted that its not part of their sponsorship equipment. Sram has already done testing on the setup & noted that any mechanical benefit is inconclusive at present. Of course if there is public demand for it, I'm sure that they will offer it at a substantial mark up.


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## WheresWaldo (Nov 29, 2005)

The savings are really non-existent if you do the math, as far as power savings is concerned but it is an interesting conversation starter. Here is a picture of the two 13T pulleys on our DA equipped tandem:

View attachment 204723


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## Pieter (Oct 17, 2005)

13t derailleur pulleys - no doubt used together with an 11t sprocket at the high end of the cassette? LOL !

The der. pulleys do not transmit power. So no mechanical benefit except lower losses through slower rotation as far as I see it.

If you are concerned about efficiency, rather delete the 11t sprocket and get a bigger front chainring.


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## Mdeth1313 (Nov 1, 2001)

Everytime I read a thread like this on RBR, I just think you guys should go out and ride old school, like back before there were derailleurs because "those things provide no mechanical advantage".

From reading about this a couple of years back, my vague understanding is it does provide some mechanical advantage, less friction perhaps, I can't remember. It is minimal at best (saves less than 1 watt- again, can't remember and not about to search) but when you're a pro you are looking for any advantage and I do remember people being able to provide the data from a mathematical/physics standpoint.


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## PlatyPius (Feb 1, 2009)

SilverStar said:


> Ha...when I saw these Berner pulleys I immediately thought of the cheapie Shimano derailleurs installed on "box store bikes"...maybe all those Wal-Mart Warriors were onto something before the pros?!?


That's what I think of, too.

"Oooo! Shimano Tourney on a TdF bike!"


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## wim (Feb 28, 2005)

Mdeth1313 said:


> From reading about this a couple of years back, my vague understanding is it does provide some mechanical advantage


Larger pulley(s) increase the total chain wrap capacity of a short-cage derailleur, which is a manufacturing / bean-counter advantage with cheaper components. But I don't know how a pro bike could possibly benefit from more wrap capacity.

Edit: sorry, ignored the "mechanical" in your comment. Given the same pulley bearing friction, the chain has an easier time pulling a large pulley around than it does pulling a smaller one. The reason is the longer lever, which is the radius of the pulley (diameter/2). While this saving is easily measured, the problem is measuring the costs incurred by more chain material in contact with the pulley. Some say the claimed 1-3 watt savings is wiped out (or worse) by that extra chain material in contact with the pulley(s).


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## Mdeth1313 (Nov 1, 2001)

wim said:


> Larger pulley(s) increase the total chain wrap capacity of a short-cage derailleur, which is a manufacturing / bean-counter advantage with cheaper components. But I don't know how a pro bike could possibly benefit from more wrap capacity.
> 
> Edit: sorry, ignored the "mechanical" in your comment. Given the same pulley bearing friction, the chain has an easier time pulling a large pulley around than it does pulling a smaller one. The reason is the longer lever, which is the radius of the pulley (diameter/2). While this saving is easily measured, the problem is measuring the costs incurred by more chain material in contact with the pulley. Some say the claimed 1-3 watt savings is wiped out (or worse) by that extra chain material in contact with the pulley(s).



this is good-- we need more contributions like this! :thumbsup: 

perhaps it's the "happy medium", there's also the "aero trumps weight" topic, but again there are limits depending on the situation


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## WheresWaldo (Nov 29, 2005)

Pieter said:


> 13t derailleur pulleys - no doubt used together with an 11t sprocket at the high end of the cassette? LOL !
> 
> The der. pulleys do not transmit power. So no mechanical benefit except lower losses through slower rotation as far as I see it.
> 
> If you are concerned about efficiency, rather delete the 11t sprocket and get a bigger front chainring.


Already swapped cassettes, using a 12-27T as we simply cannot pull a 53/11T on the flats efficiently. Can't go to > 53T as we are already at capacity for the front derailleur on a triple crank, so it's not really an option.


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## gamara (May 20, 2002)

This is a pretty silly thread if one really thinks about it. The idea behind this pulley setup is that it is believed to provide faster & smoother shifting performance. 

Why is this silly then? The best shifting group on the market at present is Di2. Hands down the most significant advance to bicycling as proclaimed by all major publications. If its the best shifting system in the world at present & it only uses a standard pulley design, then what does that make of the Berner system??


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## RC28 (May 9, 2002)

gamara said:


> Another pro fad that might or might not stay around. Remember those cinelli spincaci add on bar extensions that everyone was using at one time?? Sure they were aero but then all those nasty crashes happened because of them.
> 
> .


This is not an accurate comparison. Pros stopped using the Spinacis because the UCI outlawed them for competition . Yes, they were crashing more because of the higher speeds combined with reduced maneuverability on the bikes but they were happy to keep on crashing if it meant keeping that advantage. If the UCI hadn't outlawed them, I bet they'd still be standard issue on most pro bikes.


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## Peanya (Jun 12, 2008)

gamara said:


> This is a pretty silly thread if one really thinks about it. The idea behind this pulley setup is that it is believed to provide faster & smoother shifting performance.
> 
> Why is this silly then? The best shifting group on the market at present is Di2. Hands down the most significant advance to bicycling as proclaimed by all major publications. If its the best shifting system in the world at present & it only uses a standard pulley design, then what does that make of the Berner system??


Not silly, those pulleys can shave off 1 second in a 120 mile race.


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## Mr. Versatile (Nov 24, 2005)

I remember many years ago I experimented with aftermarket pulleys. I think Bullseye was one of the popular name brands back then. I noticed two differences: More noise, and degraded shifting performance. Things may be different now, but I'm unwilling to pay extra to find out.


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## Pieter (Oct 17, 2005)

gamara said:


> The idea behind this pulley setup is that it is believed to provide faster & smoother shifting performance.



I don't see it - the larger pulley will translate any bearing play into exaggerated sideways play compared to a normal pulley.


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## wim (Feb 28, 2005)

Pieter said:


> I don't see it - the larger pulley will translate any bearing play into exaggerated sideways play compared to a normal pulley.


I agree, and as far as I know, Wolfgang Berner never made the claim of "improved shifting." There's one other supposed advantage of the oversized pulley, but as said above, it is difficult to prove because the cost involved are difficult to measure. In a chain with less bend, the force vectors of the link pulling forces are less angled, making for a more efficient force transfer from link to link (optimum in a straight run of chain). How much more efficient? My guess is "very, very little".


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## orange_julius (Jan 24, 2003)

wim said:


> I agree, and as far as I know, Wolfgang Berner never made the claim of "improved shifting." There's one other supposed advantage of the oversized pulley, but as said above, it is difficult to prove because the cost involved are difficult to measure. In a chain with less bend, the force vectors of the link pulling forces are less angled, making for a more efficient force transfer from link to link (optimum in a straight run of chain). How much more efficient? My guess is "very, very little".


Isn't it true that larger diameter -> less wear, for the same material and chain movement speed anyway? Another small benefit, I suppose.


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## wim (Feb 28, 2005)

orange_julius said:


> Isn't it true that larger diameter -> less wear, for the same material and chain movement speed anyway? Another small benefit, I suppose.


Sure. The more teeth, the less force on each tooth. That's true for all drive train chainwheels / cogs. The smallest degree of wear is with the largest number of teeth used in making a certain gear.


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## Indyfan (Mar 30, 2004)

I would have to agree with those above questioning if this is another "pro fad" that may or may not find it's way into the main stream. The most recent example of another is the ceramic bearing debacle. Oh, I'm sorry, I imagine not everyone has stopped drinking from that "kool-aid" jug...

Bob


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## Kerry Irons (Feb 25, 2002)

*Pulling forces*



wim said:


> I agree, and as far as I know, Wolfgang Berner never made the claim of "improved shifting." There's one other supposed advantage of the oversized pulley, but as said above, it is difficult to prove because the cost involved are difficult to measure. In a chain with less bend, the force vectors of the link pulling forces are less angled, making for a more efficient force transfer from link to link (optimum in a straight run of chain). How much more efficient? My guess is "very, very little".


Knowledgeable mechanical engineers can actually calculate the difference in force transfer for small cogs vs. large cogs, but since there is essentially zero pulling force (just the derailleur spring) on the chain below the cogs, it's meaningless. This is the reason, however, why there is less energy loss when you use the larger cogs on the cassette; big ring, larger cogs is more efficient than small ring, smaller cogs.


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## barrlley (Jul 12, 2010)

Ventruck said:


> Never tired them, and there is logic behind that design, but pulleys don't play that big of a role in drivetrain power loss.
> 
> I wouldn't buy into it. Even ball-bearing pulleys can be considered overkill.



If you have ever personally tried ceramic pulleys versus the stock pulleys they put on most derailleurs, side by side, you'd realize that it actually does make quite a bit of difference in smoothness, especially if your drivetrain is kept ultra clean, like a pro rig. No wonder that pretty much all the top of the line models by each manufacturer have ceramic pulleys now. Its not that far of a stretch to believe there is some reduction in friction with a larger pulley, which is why Shimano has always used more teeth on their pulleys than, say, Campy. In the end, the improvement is probably very minimal, but if the pedaling seems ANY easier with the larger pulleys, that goes a long way mentally; and considering half of the game is mental, why would you hold that against anyone?


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## SystemShock (Jun 14, 2008)

natedg200202 said:


> I'm noticing more and more pros are using these aftermarket derailleur pulleys that are larger in diameter. Supposedly, they reduce the tight bends in the chain and reduce drivetrain losses.
> 
> Has anyone tried them? Any noticeable difference in smoothness or shifting?



Wow, interesting. I was wondering when someone would get around to making something like this.

Reason why is because there was Johns Hopkins/Shimano study back in 2000 that found that bicycle drivetrain power losses were significantly affected by cog size, i.e. smaller cogs caused the chain to bend more, resulting in greater frictional power loss (rider power output and cadence were also significant factors).

The difference wasn't _huge_ though... being in a 15t cog was maybe 1-2% more efficient than being in the 11t (which would result in being about 0.5% faster on the flat, all else being equal). Still, any pro rider would take every second he can get, I'm sure. 

Someone else brought up the point that having larger pulleys wouldn't make things more efficient because the pulleys just wrap/route chain and are 'non-pulling'. Perhaps... I'm no engineer. But if the drivetrain power losses are due to tight bends in the chain (increased friction), I'm not sure how being pulling or non-pulling would much matter... the chain bend angle's still worse with an 11t pulley, as opposed to these 'big'uns'. Does the lack of pulling tension make the entire friction issue moot? And is chordal action a total non-event too? 

Doesn't much matter to me either way though... 19.0 mph feels much the same as 19.1 mph, I'd think. Maybe I'd get something like this for the 'trick' look/having something different, if I bothered at all.
.


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## SystemShock (Jun 14, 2008)

Btw, if anyone's interested, here's the actual Johns Hopkins/Shimano study. Interesting read:

*http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf*
.


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## foz (Sep 30, 2004)

Thanks for that link, it looks like it could be an interesting read, when I find the time... as for the Berner pulleys, AFAIK they are only designed to improve efficiency, not shifting. Not sure what Berner's arguments are, but I think everthing has already been discussed here - there will be less change in angle between chain plates with the larger pulleys, so a slight gain in efficiency there and less friction between plates. The pulleys will turn more slowly than smaller ones for a given gear ratio and pedal cadence, so there will be a slight increase on pulley bearing efficiency. More chain rollers in contact with more pulley teeth will increase the overall friction in that area, so that goes against them. I don't think there is anything else. Maybe someone will do a very detailed study and find that they are slightly better than a normal pulley system, but I think the benefits will be tiny, maybe even so small that they could be more than offset by a dirty or badly lubricated drivetrain, for example. I suspect the pros use them more for any psychological benefit than any real, calculated, physical benefit. As for ceramic bearings, to be honest I haven't tried them, and certainly not in derailler pulleys, but simply using ceramic bearings will not automatically improve performance. Both ceramic and steel bearings are graded, and a high grade steel bearing will give greater benefits than a lower grade ceramic one. For a given size and number of balls, the roundness of the balls and quality of the races are much more important than the material they're made from.


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## ClancyO (Mar 20, 2011)

For what it's worth, this fad never quite went away...

https://velonews.competitor.com/files/2013/03/116.jpg


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## ClancyO (Mar 20, 2011)

Had to look them up ... 280 euro for the 'regular' and 350 euro if you want ceramic bearings ... Fad or not, that's some coin there!


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## MisterMike (Aug 12, 2004)

I regret to say that I can offer no constructive scientific comments. I can only show what my first thoughts were upon seeing the oversized pulleys. 

I wouldn't ride around in this and I don't think I could look myself in the mirror with those pulleys on my ride. Maybe if they were solid black but even then maybe not. 
View attachment 278307


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## djconnel (May 7, 2006)

So after all of this, the answer, it seems, is: no; nobody here has tried them.

The difference between these pulleys and "fads" is the analysis can relatively easily be done that they should help:

On Bicycles, and.... what else is there?: Berner 15-T derailleur pulley upgrade: an analytic model

My estimate I calculated there:

"yielding 0.46 watts for the 39-tooth ring and 0.62 watts for the 54 tooth ring."

So I've had an interest, but the cost is a deterrent.


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## AndreyT (Dec 1, 2011)

wim said:


> Sure. The more teeth, the less force on each tooth. That's true for all drive train chainwheels / cogs. The smallest degree of wear is with the largest number of teeth used in making a certain gear.


That is true, but it can only make any practical difference when the cog is transferring significant torque, resulting in significant force distributed among all engaged teeth. I.e. it matters for chainwheels and it matters for cogs. 

The only load present on engaged teeth of a pulley is derived from the friction in the pulley axle. There's no other load. This load is so disappearingly small, that it won't have any detectable effect on wear.


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## Pirx (Aug 9, 2009)

Ventruck said:


> Never tired them, and there is logic behind that design, but pulleys don't play that big of a role in drivetrain power loss.


Actually, the pulleys play a major role in the drivetrain power losses, but overall the losses we are talking about here, and the possible improvements with those pulleys, are still quite small.



barrlley said:


> Its not that far of a stretch to believe there is some reduction in friction with a larger pulley, which is why Shimano has always used more teeth on their pulleys than, say, Campy.


Huh? Where did you get that idea? In fact, it was Campy who used to have the larger 11t pulleys first. On the current groupsets, both use 11t pulleys.



foz said:


> More chain rollers in contact with more pulley teeth will increase the overall friction in that area, so that goes against them.


That part is irrelevant, since the chain is not moving relative to the pulley where it is wrapped around it.



djconnel said:


> My estimate I calculated there:
> 
> "yielding 0.46 watts for the 39-tooth ring and 0.62 watts for the 54 tooth ring."


Yeah, about a half Watt sounds about right. In other words, the improvement is in the noise: Wear a tight-fitting jersey, and make sure your zipper on the jersey is completely closed, and you'll gain more. Heck, even shaving your legs may help more than that...


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## djconnel (May 7, 2006)

Yes, in the noise is right. Watch your power meter and the number jumps +/- 10 watts. You'd never notice a half-watt. But on the other hand, it's enough that if I were climbing a hill that takes 1000 seconds, it might take a few seconds off that, and in racing that may be important, but then as you note many other things are at least or more important (like cleaning your drivetrain). If you're riding a gran fondo, probably not.

But then my calculations contain a lot of rough assumptions and it would be better to have clean measurement data.


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## Brock4 (Apr 19, 2017)

Does anyone know if I swapped out my sram red short cage for an oversized pulley system, if it would allow the derailleur to run a 32t cassette? Only asking because it would be cheaper to do so rather than buy a whole new wifli derailleur... 


Sent from my iPhone using Tapatalk


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## Notvintage (May 19, 2013)

MR_GRUMPY said:


> Anytime you see "new" things on a Pros bike, you can be assured that they were paid to put them on.


Far from true. Lot's of pros were buying carbonsports Lightweight Wheels on their own.


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## cxwrench (Nov 9, 2004)

Brock4 said:


> Does anyone know if I swapped out my sram red short cage for an oversized pulley system, if it would allow the derailleur to run a 32t cassette? Only asking because it would be cheaper to do so rather than buy a whole new wifli derailleur...
> 
> 
> Sent from my iPhone using Tapatalk


Wut? You can buy a new WiFli rear derailleur for $250.00...a CeramicSpeed pulley/cage kit is $499.00. Unless you've got eTap, then you're saving $100.00. The WiFli derailleur will shift better because the angle of the pulley movement is changed.


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