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Sram RD tuning

Discussion on bikes, and whatever...

Sram RD tuning

Postby Boonen » Tue Sep 30, 2008 12:10 pm

Here are some pictures of a tuning job I did for a friend last winter.
He was building a new bike and wanted something 'special and light', the reason for picking the force over the red derailleur was pretty simple as the red wasn't on the market yet when I started this. Having seen the red I doubt there is all that much different in the parts that I left on it. The derailleur has been 'in service' over the summer and seems to work as expected but I haven't been allowed near one lone enough to take it apart and put the pieces on a scale, yet.

I started replacing all the bolts with aluminium one's and replacing the 4 steel pivot rods with titanium rods. I think the Red even has aluminium rods but I didn't know that back then and since I knew this would see a lot of use I didn't want to compromise durability and picked titanium. That however leaves for some additional weight savings by either choosing aluminium or even carbon tubing.

The tuning bolt was taken out and the steel insert that normally holds it was removed. Some aluminium was cold welded in the hole and tapped to work with a standard M5 threading.

The rear plate has been replaced by a copy of it in carbon. Special thanks goes to Stephen from FibreLyte for helping me get the carbon material and also for helping out with the pulley wheels :top: I made another (slightly heavier) version of it as well that prevents the chain from falling off on the outside of the upper pulley wheel much like the current Red derailleur has but I don't think it has been used yet.

Other then that it's simply drilling, filing, sanding, reapplying clearcoat to the carbon and then some polishing.

Of course the idea in all this was not just to get something a bit different looking but also to save some weight, it ended up at 119,0 grams. As said there is still some more room to save weight by replacing the pivoting rods and I know there are also lighter pulley wheels available then the FL one's but I like these, and besides if you want you can have FL provide you with some smaller side pieces that will help acomodate the smaller M4 bolt that sram uses for their top pulley.

Having it anodized would be nice but since there are steel bushings pressed inside the aluminium where the pivot bolts enter the body this is not (easily) possible so it's just polished. The aluminium isn't of the same kind of quality as Campagnolo and Shimano uses (but then again, I don't think they expect you to drill and cut in it :wink:) but the polished surface holds up quite well.



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Postby Roy Batty » Tue Sep 30, 2008 12:26 pm

Love it; and the pics are fab as well. I want to do the same on a Record rear mech, but want it all black. Will have to delve into the past as Felix I'm sure did one.

I really like the new Record 11 in the looks stakes, but missed a beat with me as the cassette is 12/27 and I want to keep my 13/29. So, have bought the 2009 Centaur, which I also want to 'butcher' into shape and lose some weight.

Any suggestions?

KB
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Postby KF » Tue Sep 30, 2008 2:12 pm

Incredible - do you have a pic of it on the bike?
//KF

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Postby Thomskie » Tue Sep 30, 2008 4:55 pm

Nice job Boonen :positive:
As KF mentioned it before a full pic would be great
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Postby Ypsylon » Tue Sep 30, 2008 5:36 pm

Not much left of the derailleur. Great job. :thumbUp:
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Postby Boonen » Tue Sep 30, 2008 6:22 pm

Thanks guys. I don't think I have a picture of it on the bike. As said it isn't something I have been riding myself but I'll see what I can do.

KB, I don't really know the Centaur but have taken a record apart a few times. Of course you could start with replacing all the obvious bolts, the mech plate and the pulley wheels, that would save you a good bit of weight. (The pivot bolt is the same for Shimano and Campy, I got mine from Probolt) After that you could look at replacing the springs with Ti one's as that saves quite some weight as well relative to what the whole thing weighs. The adjustment bolt where the outer cable goes into is rather heavy as well. I don't think it's possible to just push out the steel insert (I tried in a vise as hard as I dared) but you can drill it out, tap a normal threading in it and use an aluminium bolt. It would be easy if you could take the whole thing apart, I know the record derailleurs have pivot bolts with a thread in the end so you can screw them out, not sure about the Centaur though. If possible there is a steel plate holding the limit screws riveted behind the carbon part of the body. That's rather heavy. You can see on the sram derailleur that I left out the lower limiting bolt, I don't think you need that. The upper one is nice to have though so you can't push your derailleur into your wheel to easy. I'd say you won't loose much by cutting off half of the steel insert. What you could do is replace the outer mech plate by something out of carbon as well. (I did this on another project that I will post soon so stay tuned for more idea's here :wink:) That or you could just drill a bunch of holes in it pretty much the same as in this one or as the DA one that Madcow posted a long time ago. Don't forget to drill the shaft that goes into the body as well, it's steel so you can save a few grams there as well. Other then that it's mostly creative drilling and sanding and how far you go depends on how much work you want to put into it. The drilling is free but the other suggestions will save you more weight. Hope this is of any help, let us know how it turns out! :top:
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Postby BMANX » Sun Oct 26, 2008 8:04 am

Boonen,

I am just about to finish my new build and am hoping you can have some suggestions in regards to tuning my new RED derailleur. I have most of the aluminum bolts left over from my Dura-Ace 7800 tuning and also have a pair of FL carbon pulleys that Stephan sent me a while back. That will help but where else should I look for tuning possibilities.
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Postby Boonen » Sun Oct 26, 2008 10:17 am

Sure, what do you want to do/know? Do you only want to change bolts or do you want to drill and file as well?

I saved a lot of weight by changing the adjustment bolt (the one where the cable goes through). The insert was steel, is that still the case for the Red derailleur?

Note that the upper pulley is fixed with an M4 bolt, not and M5 like on your DA derailleur. Stephen suggested he could make me custom sideplates for the FL pulleywheels with a 4mm hole in stead of a 5 mm hole, but the stock pulleys seem to work fine. Madcow also told me he was doing fine with his Red derailleur and KCNC pulleywheels so unless you're ordering new ones I'd say try the current ones first. If you're not happy with how it shifts you know about the option.

Other thing I saved a lot of weight with was replacing the pivot bolts. On the Force derailleur they are steel. You could check what they are on the Red, I didn't test it with a magnet but I think they are aluminium? I replaced mine with Ti tubing as that seemed like the most durable option, made the action of the derailleur butter smooth as well :D
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Postby BMANX » Sun Oct 26, 2008 2:45 pm

Boonen - Thanks for the quick reply. I do not want to cut or drill into a new rear derailleur at this time but maybe down the road. The objective is to use a stock derailleur and tune it as much as possible wtih just bolts and pulleys. I will contact Stephan about the pulleys as I also need to get some custom spacers for my 1 X 6 project. Just need to measure up the distance needed for both and work out chainline.

I already have the pulleys for this project but do you know how much the stock pulleys weigh. I think that the pulleys on the RED are ceramic but I would rather save the weight then care about the ceramic bearings. I do not have the derailleur yet as I am waiting for it to arrive.

Cheers.
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Postby Fibre-Lyte » Sun Oct 26, 2008 9:23 pm

Brian,

the stock pulleys will work fine on the Red rd, but if you want more accurate placement for the top pulley, then we can do the top spacers with 4.2mm holes to suit the smaller top bolt.

Incidentally, a company we deal with for model car parts is bringing out a range of coloured/ti bolts for the various front and rear rd's. They're hopefully sending me a blue record set very soon, so as soon as they arrive, I'll weigh them and post pics :wink:
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Postby BMANX » Fri Oct 31, 2008 3:56 pm

So I was able to install my Fibre-Lyte pulleys and a black anodized bolt where the cable is pinched and the weight with just these modification is now 131g. The stock derailleur was 145g when it arrive which is 8g lighter than posted on Sram's website.

So now I just have to wait for Stephan to get back to me with the expected weight savings of the Ti bolt kit from the company he deals with and I hope that changing over the bolts would get me down to 120g which would be very nice.
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Postby Boonen » Fri Oct 31, 2008 4:31 pm

Bman, I don't think you'll save any more weight, if the bolts you are looking at are all Ti then you'll even gain weight as the rest of the stock bolts are all aluminium already.
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Re: Sram RD tuning

Postby BMANX » Sun Nov 02, 2008 10:55 pm

Boonen - Do you know how much tuning Sram did to the Red to get it down to 145g stock. The reason that I ask is that my Dura-Ace 7800 had to have all aluminum and a Ti spring to get to 141g and all I have done to get the RED down to 131 was a pinch bolt (aluminum and lighter) and pulleys. Did they use a lot of aluminum parts in the building of the rear derailleur and is that why you suggested to not go with the ti bolts?
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Re: Sram RD tuning

Postby coloclimber » Wed Nov 05, 2008 1:02 am

Can someone help me with tuning the Red cable adjuster bolt?

The whole mechanism is weighty but my aftermarket allow bolt wont fit in there and still have threads to adjust the cable tension.

With carbon pulleys and plate the Red RD was 128 grams.

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Re: Sram RD tuning

Postby BMANX » Wed Nov 05, 2008 1:32 am

Where did you get the carbon back plate from?
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