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Sram RD tuning

Discussion on bikes, and whatever...

Re: Sram RD tuning

Postby BMANX » Mon Nov 24, 2008 7:20 pm

Boonen - How often do you adjust your rear derailleur? I was thinking the same as what you did. Take the M8 thread and drill and tap a 5mm hole so that I could use my aluminum cable tension bolt to do some adjusting but then I started to think that I never really play with the tension very much. If the cable stretches then I just loosen the pinch bolt and redo the tension.

I am not sure what the the weight difference would be but I think if you use a long enough M8 bolt, you should be able to still do the tension as well.
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Re: Sram RD tuning

Postby Boonen » Mon Nov 24, 2008 9:54 pm

Maybe not that often but I think it's a nice thing to have, especially when setting up new cables. I guess it's a personal thing. If you drill a larger hole and fill it with an aluminium bolt the weight should stay about the same. If you still have the head on that M8 bolt it'll even go down. As said the nice thing about the sram derailleurs is the cable guide in the arm as it doesn't really matter how you position the cable, it'll always pull in the right direction. If you try to do the same with a DA derailleur (take out that little steel ring that keeps the cable from eating it's way into the aluminium f.i.) it won't shift as well.
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Re: Sram RD tuning

Postby BMANX » Mon Nov 24, 2008 10:16 pm

Boonen,

How did you drill out your bolts? Did you use a drill press or did you do it another way. I have a drill press at home but it is just a cheap one and when I did the other modification this weekend, I just did it with a hand drill.

The only thing that I do not own is the taps which I have been meaning to get for a long time so I will pick them up this week. I can just get the guys in the shop to do it but it is not the same as doing it yourself. However, it is a lot more accurate.
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Re: Sram RD tuning

Postby Boonen » Mon Nov 24, 2008 10:32 pm

I used a hand drill on the part I welded in the derailleur. A lathe or a maybe drill press would probably have been more accurate but would require you to make a fixture for the derailleur that sets it up just right and accuracy doesn't matter to much for this bolt so I just used the hand drill instead.
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Re: Sram RD tuning

Postby BMANX » Mon Nov 24, 2008 10:41 pm

I forgot that you welded the part into the derailleur. I do not want to weld anything so I might go with the 8mm bolt with longer threads and use it as the new cable tension bolt.
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Re: Sram RD tuning

Postby BMANX » Tue Nov 25, 2008 2:09 am

Boonen - I just got back from picking up some new Ti parts.

Well actually Ti drill bits that were on sale for $40 CDN. They had a sale on a 112 piece drill bit set that are normally $100 on sale at 60% off so I just could not resist going in there and also picking up a new tap & die set as well.

112 piece drill bit set - Check

60 piece tap and die set - Check

500 piece dremel set - Check

Let the tuning begin.

Oh I guess I better order the aluminum bolts tonight as well. That sort of plays a major role in the tuning of the Red Derailleur but not a major roll in all the tuning I would like to do.
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Re: Sram RD tuning

Postby Boonen » Wed Nov 26, 2008 10:04 pm

Sounds like a killer set of drills! And 60 taps :shock:
Have fun :top:
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Re: Sram RD tuning

Postby BMANX » Wed Nov 26, 2008 10:28 pm

60 piece tap and die set.

I still have to place a bolt order and just need some time to sort out what I need to order.
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Re: Sram RD tuning

Postby BMANX » Sun Dec 14, 2008 12:46 am

Today I decided to take the plunge with finishing the tuning of my Sram Red RD. I removed the stock Cable Tension Bolt and did what I never thought that I would do. Modify a $300+ rear derailleur. The only issue that I could see was that the hole that I was going to drill and tap was just a shade bigger than the suggested hole size for the M8 tap. I ordered 6 M8 X 25mm bolts to use for this project.

First bolt I drilled out to M5 and tapped the inside. I cut off the head of the bolt to just use the threads and was going to use an M5 bolts drilled out to run the cable through and drill the head out to fit the Nokon cable end. The issue with this route was that the threads on the rear derailleur were just a bit too loose to hold the M8 thread and even with loctite it would just not hold correctly. I was shitting my pants thinking that I just ruined the rear derailleur.

Second bolt I decided to leave just a bit of the head on the bolt and drill and tap the inside to M5 again. I thought that if I screwed the bolt through the back of the hole for the cable tension bolt that it would pull tight and hold very well. This proved to be a great way to hold the bolt in place but I screwed up on the drilling a bit and the hole did not go as straight as I would have liked.

Third bolt was done the same way but again the hole was not as straight as I would have liked which is damn difficult to do with a hand drill at home held in place with a vice. It does work very well and with the aluminim M5 cable bolt that I have and a stock spring, this system will work very well and only adds 2g which is about 6g lighter than the stock cable tension bolt system. I will add some blue loctite to the bolt when I install it on the final version which should hold it in place well enough.

I have three bolts left so I am going to draw the bolt up on paper this weekend and take it too work on Monday and get the guys in the machine shop to do this on the proper equipment so that the bolts are drilled perfectly on center and will get them to turn down the heads to my specs as well. I even had some carbon spacers kicking around that I modified into carbon washers to hold the whole thing really tight but I do not think that I need the carbon M8 washers now as the spring and flange on the M8 bolt will do a good enough job.

The total weight of the rear derailleur is currently at 122g after I installed the new carbon plate that I got from Fibre-Lyte this week and I also swapped out the stock adjustment bolts to nylon. The stock pinch bolt was changed out for an anodized aluminum bolt. I forgot to mention that the pulleys are also Fibre-Lyte Carbon.

I think that 122g is about as low as I will go on this project which will keep my happy. This is a lot lighter than I could have got my Dura-Ace 7800 with the same amount of tuning. Actually I had done more tuning on that one and it was about 20g heavier.

My camera broke 4 days ago so I will try to post pictures when I can find a replacement.

Cheers.
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Re: Sram RD tuning

Postby BMANX » Sun Dec 14, 2008 7:21 pm

Here are two pictures and I will try to post a few more when I have some more time.

Image
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Re: Sram RD tuning

Postby Boonen » Sun Dec 14, 2008 7:33 pm

Looks great Bman, I like how you fixed the new barrel adjuster, nice. :top:
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Re: Sram RD tuning

Postby BMANX » Sun Dec 14, 2008 8:37 pm

Boonen,

Like I had mentioned, the new barrel adjustment set up will be way more pro with the guys in the shop doing this work on a lathe instead of me doing it with my hand drill. To reduce the head of the bolt, I had to put the bolt in the drill and clamp the metal file in the vise and spin the bolt in the drill to reduce the head size down. Much quicker on a lathe.
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Re: Sram RD tuning

Postby mtbwrx » Wed Dec 17, 2008 11:59 pm

pardon for butting in gang,
maybe a dumb question, but do the after market / custom pulley's make more noise or less than a standard stock pulley?

has anyone had any of these carbon cage units snap?
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Re: Sram RD tuning

Postby Boonen » Fri Dec 19, 2008 6:58 pm

I have heard about the carbon inner cage (the one closest to the spokes) snap if you make it to light.
I can't say I notice any more or less noise from the aftermarket pulleys that I have tried but then again I haven't really payed much attention to it.
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Re: Sram RD tuning

Postby Xav » Thu Jan 08, 2009 12:01 pm

Sram Red , rear Derailleur tuned / new paint.
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