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Educate me on Derailleur Pulleys
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Derailleur pulleys are either made of Delrin or Aluminum. I've even seen carbon ones which make no sense to me. What are the advantages of Delrin over Aluminum? or Aluminum over Delrin?

Aluminum seems noisier while Delrin is quieter in my experience.

Does Aluminum help shift better? I've tried googling this stuff but all I can find is debates over different pulleys (ceramic bearings, etc)

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Last edited by: BryanD: Jun 29, 15 10:58
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Re: Educate me on Derailleur Pulleys [BryanD] [ In reply to ]
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The only time I've found that an aftermarket pulley worked better than a stock pulley was when the OE pulley was pretty bad.

Metal pulleys are, IME, noisy. If you're looking for better shifting--and your stock pulleys aren't worn out--spend your money on better cables/housing.

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Last edited by: GRAVELBIKE: Jun 29, 15 15:06
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Re: Educate me on Derailleur Pulleys [BryanD] [ In reply to ]
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The friction at the cog/chain interface is negligible (especially so due to the low chain tension), so AL vs. plastic doesn't really matter. The two items that do are cog tooth count (more teeth equals less bending or the chain links, so reduced chain friction) and bearing type (bushing, std. bearing, or ceramic).

Aftermarket pulleys are typically AL with bearings. The AL is mostly for a higher end appearance and to cut weight. Personally, I swap out the pulleys with bushings from my lower-end RDs with ones with bearings, and bump up the tooth count if they will fit in the cage.

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Re: Educate me on Derailleur Pulleys [BryanD] [ In reply to ]
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I've found that delrin pulleys give me consistent speed based on my AvgP/NormP when I am outdoors or indoors on the trainer. When I ride aluminum pulleys my speed isn't the same outdoors/indoors despite the power being the same. When i ride carbon pulleys on the other hand my AvgP is always the same ascending and descending. Anyone know how I can ensure my lap speed is the same despite what pulleys I ride?
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Re: Educate me on Derailleur Pulleys [Pantelones] [ In reply to ]
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hahhahaha way to be a jackass. Funny post though and I love the reference to the bike computer/trainer/why doesn't my computer learn me thread

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Re: Educate me on Derailleur Pulleys [Titanflexr] [ In reply to ]
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I have the Enduro Bearings Zero pulleys that are hybrid ceramic and made out of Delrin. I was curious why companies like Hawk Racing and Ceramic Speed use aluminum for their pulleys. The Enduros weigh 9 grams total for the set compared to the 24 gram Ceramic Speed and 17 grams for Hawk Racing. If it's to cut weight, Delrin seems to be lighter.

I had some cheap chinese aluminum pulleys once and they drove me crazy with how loud they were

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Last edited by: BryanD: Jun 29, 15 15:06
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Re: Educate me on Derailleur Pulleys [BryanD] [ In reply to ]
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I would guess that the majority of the weight is in the bearing system vs. the cogs. I've got some cheap Chinese aftermarket pulleys that come in at 10g, and there are some carbon fiber ones that are sub-7g. Often the savings is by going with smaller bearing cartridges. As far as wear goes, I've rarely seen a worn out gear section of a pulley on a road bike (does happen on XC and MTBs where all kinds of abrasives end up gunked on the chain).

As far as performance goes. It looks like gains in this area top out at ~1W (assuming you are starting with a bad setup). Friction Facts has some test results (for $5).
http://velonews.competitor.com/...ockey-pulleys_284386

ECMGN Therapy Silicon Valley:
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Re: Educate me on Derailleur Pulleys [Titanflexr] [ In reply to ]
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The reason I bought the Enduros was from the Friction Facts test.

I'm just interested in material choice

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Last edited by: BryanD: Jun 29, 15 15:49
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Re: Educate me on Derailleur Pulleys [BryanD] [ In reply to ]
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Given the FF data, looks like you're all set.

To the original question re: cog material: the loads are so low the answer is that it really doesn't matter. They don't really play a role in shifting precision (some mfgs. even leave a little play in the top pulley so that it won't put any lateral force on the chain). I'd speculate that aftermarket guys went to AL since it looked different/better than "plastic." The carbon fiber pulleys are just for bling value.

The noise issue might be a reason for a preference, but isn't in and of itself an indicator of quality. The original SRAM powerdome cassettes were so loud that it sounded like something was broken each time you would shift, but they were light, rigid, and worked great.

ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)
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Re: Educate me on Derailleur Pulleys [Pantelones] [ In reply to ]
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Pantelones wrote:
I've found that delrin pulleys give me consistent speed based on my AvgP/NormP when I am outdoors or indoors on the trainer. When I ride aluminum pulleys my speed isn't the same outdoors/indoors despite the power being the same. When i ride carbon pulleys on the other hand my AvgP is always the same ascending and descending. Anyone know how I can ensure my lap speed is the same despite what pulleys I ride?

Chapeau to you!
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Re: Educate me on Derailleur Pulleys [BryanD] [ In reply to ]
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I have a set of the KCNC alloy pulleys on my backup bike and haven't noticed any difference in noise or shift quality vs the stock SRAM plastic ones. I bought these purely for the bling factor, nothing more. I haven't had them long enough to see if they wear longer or not.
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Re: Educate me on Derailleur Pulleys [JesseN] [ In reply to ]
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JesseN wrote:
I have a set of the KCNC alloy pulleys on my backup bike and haven't noticed any difference in noise or shift quality vs the stock SRAM plastic ones. I bought these purely for the bling factor, nothing more. I haven't had them long enough to see if they wear longer or not.

Me too....for the bling that is. When the SRAM wheels wore out on two bikes I replaced with red anodized aluminum. I could not tell the difference one way or another. I have not received any compliments on the bling style. Both sets on the bikes are holding up well.


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Re: Educate me on Derailleur Pulleys [BryanD] [ In reply to ]
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61 posts on this thread I started a few years ago.

http://forum.slowtwitch.com/...ey%20pulley;#4456265

jaretj
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