Sram rear Der. Upgrade to 15th lower pulley

Discuss light weight issues concerning road bikes & parts.
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dark_albert
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by dark_albert

Hi guys,

i spend a few hours in the workshop.

I tuned my Rival rear der. to 15th lower pulley.
Weigh is at 170g. Still light.
http://picasaweb.google.com/dark.albert ... sumbauSram


dark_albert

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marecej
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by marecej

what for?
Ellsworth Truth = 9371g

by Weenie


dark_albert
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by dark_albert

do you mean what sence does it make?

it saves you power. Take a look at the search funktion. there are some threads about this.

dark_albert

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CharlesM
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by CharlesM

There are also a few threads (or were) about running SRAM with something other than stock pulleys...

I believe depending on what you do, you run the risk of too much swing and rear DER failure.

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SirVelo
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by SirVelo

@ dark_albert: once again a really nice execution. Well done. Do you notice any extra flex in the RD now? You'll have to post some comments after you've put some miles on it.

@ pez or anyone else reading this thread that has the answer (and sorry for the slightly off-topic thread jacking :oops: ): I have only heard of Rival RD's failing. What about the Force RD? I have some carbon pulleys (11t) and a carbon cage back plate on mine - just switched from a heavier set of KCNC pulleys. Should I be worried?
This board and the world in general would be a much nicer place if everyones opinion was respected and if knowledge was shared and not slung around.

GrahamB
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by GrahamB

dark_albert wrote:it saves you power.


:lol: How many milliwatt?
Graham

too slow
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by too slow

All it needs now are dimples.

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djconnel
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by djconnel

PezTech wrote:There are also a few threads (or were) about running SRAM with something other than stock pulleys...

I believe depending on what you do, you run the risk of too much swing and rear DER failure.


Shouldn't a larger diameter pulley increase the effective cage length, increasing the derailleur capacity?

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Boonen
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by Boonen

Looks good Dark-Albert! Did you manage to get the original cage off the plastic parts it's fixed to without damaging it or did you just cut it off and use the remains to fix the carbon plate to? I have been looking for options to remove the outer arm from the plastic part with the feather inside but I haven't found a way to do so without damaging it to much to get back together again in the right way.

Anyway, I love your tuning jobs so thanks for sharing :thumbup:

dark_albert
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by dark_albert

hi, i just cut it. i didn´t found a way to rebuild it either. But i get some contact to sram right now. maybe i can get some closer infos how to rebuild it.

dark_albert

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Boonen
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by Boonen

Sounds good. I'm working a little on one of these as well so if you find a way around the pressed in pin maybe you could let us know? It would be convenient if they would use a small m4 or so recessed bolt instead of a pressed in pin just like the cheaper Shimano derailleurs do, it would also help people with damaged derailleurs replacing only the cage if necessary.

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djconnel
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by djconnel

Old thread, but I asked Greg Steele, who has one of Dark Albert's mod'ed Red deraillaurs, to give the pulleys a 'spin test". My SRAM pulleys spin for two seconds, which makes me happy, because that's much better than Shimano pulleys, which don't freely spin at all (based on my tests on old Dura-Ace on and what I've read @ BikeTechReview). Anyway, here's the result:

http://vimeo.com/13964141

WOW! Of course, unloaded friction isn't necessarily proportional to loaded friction, but nevertheless, that is really impressive.

pierre-san
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by pierre-san

OMG! :shock: They spun forever! Impressive indeed.

KWalker
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by KWalker

I tried searching, but didn't use the right combo of terms and I want to know where to get the parts and if anyone has further tested this idea. I'm thinking of doing it to my Force der.
Don't take me too seriously. The only person that doesn't hate Froome.
Gramz
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djconnel
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by djconnel

I put my best attempt at modeling the effect of the 15-T cog here.

Here's the link to Dark Albert's service.

by Weenie


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