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Sram RD tuning

Discussion on bikes, and whatever...

Re: Sram RD tuning

Postby Boonen » Wed Nov 05, 2008 10:07 am

Bman, sorry for the late reply. Here is what Jason had to say about it in the Red topic in the Drivetrain review section:

madcow wrote:
Boonen wrote:Madcow, could you tell me the weight of the rear derailleur like it is mounted on the bike, with the KCNC pulleys and the tuning bolts?


About 1-2 grams heavier than it was stock.

As for the tunability of the parts, different people would reach different opinions. For just bolt tuning there is practically nothing you can do, as everything is already ti or aluminum. If you really wanted to save weight, you'd have to start changing parts and drilling.


I haven't been allowed to take a Red derailleur apart yet and I don't ride Sram so don't feel like buying one myself just to experiment with, but I'm quite sure that most bolts that you are looking to replace with Ti bolts are already aluminium. Only thing that I'm not sure about is the pivot rods, could somebody check those with a magnet? I used Ti just to make sure it would be strong enough but there are plastic bushings on the inside preventing wear of the rods so aluminium or even carbon tubing shouldn't pose a problem. Nice side info is that it's the same size (4mm) as the pivot rods in a Record FD so you can use the same material on both derailleurs :D

As for the cable adjustment bolt, that whole insert thing is rather heavy and I don't completely understand whey Sram went for this solution but think is must have to do with production processes as it's easy to mount and take out. What I did was take it out, drill through and largen the hole, tap M8 thread in there and then weld an aluminum M8 bolt in there that I later ground down flush with the rest of the derailleur. I went the easy way but I guess if you're a good welder you could skip the tapping part and just fill/close the hole with welds. Once it's done I doubt you could really see a difference though.
After that I drilled in a new hole tapping it with M5 thread and used a regular bolt what I also drilled out. You can buy both M5 and M6 aluminium adjustment bolts though which look nicer, but I decided to just use what I had around for now. With Shimano and Campagnolo derailleurs the angle at which the cable leaves the adjustment bolt matters for the precision of the shifting. If you mess things up there the derailleur will shift differently. On the Sram derailleurs there is a cable guide directing the pull of the cable so essentially it doesn't matter how you drill the new hole for the cable to go through. The cable won't rub at it at an angle either so there is no need for a steel insert like on the DA derailleurs. Just try and get it as straight and in the same position as the stock adjuster and you'll be fine.
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Re: Sram RD tuning

Postby BMANX » Wed Nov 05, 2008 4:00 pm

I did start to take off the cable adjustment bolt and was actually shocked when I saw it. I already have some aluminum adjustment bolts from other projects and I am thinking of actually filing one of the bolts down to the same style that Sram does. I could save a little there. Also as per Coloclimber's post, I think I might see if Stephan at Fibre-Lyte can make me a new carbon back plate to reduce some weight there a bit.

I think that I might also try to take apart the cable adjustment and see what I can do.

So basically the only tuning that is easier to do is the pulley's to carbon, the carbon back plate and maybe the cable adjustment bolt area with a little filing of a new bolt.

Well that is a little sad :( but at the same time Sram has a pretty nice light stock rear derailleur. I had to do a lot to my Dura-Ace to get it too 141g and my Sram came stock at 145 so I can see that there is not a lot of bolt tuning available.
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Re: Sram RD tuning

Postby coloclimber » Wed Nov 05, 2008 7:43 pm

DarkAlbert made the pulleys, rear plate (and screw) - stefan_schaeufle @ gmx dot de.

Even though the cable adjustment bolt "system" on the Red RD is 8 grams (IIRC) and could be tuned to ~1.5 gr , the whole drilling out and tapping threads thing makes me think its not worth the hassle. It truly is a stupid mechanism on SRAM's part but 128gr is not so bad for a RD. :grin:
A Super Record 11 is $500 and weighs 172 grams after all.
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Re: Sram RD tuning

Postby Gold Knight » Wed Nov 12, 2008 4:13 am

my SR11RD came in at 159 grams with carbon back plate and Schmolke carbon pulleys!--shifted fine--no other parts were touched (YET)
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Re: Sram RD tuning

Postby Simon BP » Wed Nov 12, 2008 10:27 pm

Damn! Now that I have seen your beautifull job on this Force RD and the Dura Ace RD, I don't dare to show my frankenstein of a Record RD project :lol:
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Re: Sram RD tuning

Postby j0m » Wed Nov 12, 2008 10:42 pm

Simon, I'm holding my breath. Hurry! :wink:

Seriously, please share your project. I think the forum would be quite boring if you could only post about stuff that is greater than anything seen before. Most people wouldn't even dare to mess with their parts so even if it happens to be Frankenstein's monster it's still an achievement.
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Re: Sram RD tuning

Postby Simon BP » Thu Nov 13, 2008 1:31 pm

Belive me, it does look like Frankenstein's dead mother! :S but it is also ok light. right now it is at 135g with stock pulley's and mechplate. that will drop to aprox 115-116g with Rothshek carbon pulley's and mechplate. it was an old Record rear d. I got with some other parts that I bought a while ago, and it had been in a crash so it didn't look very well. So I just started the drill and started drilling holes in it whereever there was room for one :lol:

picture will be add'ed soon..
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Re: Sram RD tuning

Postby Boonen » Thu Nov 13, 2008 4:11 pm

Sounds good Simon, by replacing the pulleys and rear plate I think you could save somewhere around 20 grams indeed so that's a light RD for sure, looking forward to the pictures :top: I still need to do some work on a serious Record RD tune job some day so any ideas are welcome :D
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Re: Sram RD tuning

Postby Simon BP » Thu Nov 13, 2008 4:19 pm

Boonen wrote:Sounds good Simon, by replacing the pulleys and rear plate I think you could save somewhere around 20 grams indeed so that's a light RD for sure, looking forward to the pictures :top: I still need to do some work on a serious Record RD tune job some day so any ideas are welcome :D


don't look after what I have done! I was simply insane! and I don't belive it's safe do ride anymore :roll: I'll post a picture when I come home from school today..
EDIT: here is a single small picture. this topic isn't aout my RD, so wont make anything large...


Image
Last edited by Simon BP on Fri Nov 14, 2008 5:23 pm, edited 1 time in total.
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Re: Sram RD tuning

Postby Anaszi » Fri Nov 14, 2008 12:47 pm

Awesome. I want one
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Re: Sram RD tuning

Postby Boonen » Mon Nov 17, 2008 11:56 am

That sure is a budgers job Simon :lol: And with some different bolts, springs and pulley wheels it could be much lighter again. I'm not sure if it would be safe to ride though, as you also brought up. I wouldn't be to happy with myself if I had put that on the bike and it broke ruining the rear wheel and the frame ...
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Re: Sram RD tuning

Postby BMANX » Sat Nov 22, 2008 10:51 pm

Alright Boonen I need some advice. I decided today to take the Sram Red derailleur apart and I have decided to tune it further and get rid of the cable tension bolt set up. So I popped it off (in the process snapped the retaining ring on the back in half) and have decided to buy an anodized black M8x20 bolt and will tap the derailluer for the M8 bolts. I will get the guys at work to drill a 2mm hole in the M8 bolt and then drill out the head to accept a Nokon housing end.

I guess what I am asking is do you think this will work?

Not sure if I made myself clear enough. I will also pick up some anodized black bolts for the rest of the derailleur at the same time. Most likely the 3 limit bolts only as I have a black aluminum pinch bolts already installed.
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Re: Sram RD tuning

Postby BMANX » Sat Nov 22, 2008 10:54 pm

One last question for anyone this time. Is the inner plate on the Red the same as the Force inner plate. The only reason that I ask is because I know that Fibre-Lyte has the Force inner plates designed but they do not have the Red inner plate designed and I was wondering if I could just use that one.
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Re: Sram RD tuning

Postby BMANX » Sat Nov 22, 2008 11:55 pm

I had an aluminum V-Brake post in 8mm in the garage so I modified it today to hold the Nokon cable end and drilled a 2.5mm hole for the cable to go through. End result was a 2g cable tension bolt to replace the heavier Red set up. The only issue is with the length of the bolt. There is no way that I will be able to tension the cable but it is a pretty slick 2g 8mm cable stop :)
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Re: Sram RD tuning

Postby Boonen » Sun Nov 23, 2008 7:10 pm

Sounds good to me. What I did was cut of the head of the M8 bolt, drill a larger hole and then tap M5 thread in it so I could use an adjustment bolt. Depending on your frame I'd say that's a nice thing to have without really adding any weight.
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