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from the east
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I don't have much experience with EBBs, so this is theory, but:

Won't the interface now be under more stress, seeing as the clamping area is narrower? Therefore, more prone to creaking and loosening? There is clearly a reason you didn't want to machine it down all the way to 2 inches even, say.

If it was me, I would have machined only the non-drive side of the eccentric and the shell, and kept as much material as possible closer to the centerline of the chainring.

Eric.
 

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Bicycle Rider said:
I don't have much experience with EBBs, so this is theory, but:

Won't the interface now be under more stress, seeing as the clamping area is narrower? Therefore, more prone to creaking and loosening? There is clearly a reason you didn't want to machine it down all the way to 2 inches even, say.

If it was me, I would have machined only the non-drive side, and kept as much material as possible closer to the centerline of the chainring.

Eric.
I think in the case of a "set screw" ebb, like this one, there is no problem since the "contact area" where the screws actually contact is practically the same...
 

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A good example of a set screw type ebb.

http://www.ninerbikes.com/images/bigNiner's-super-light-110.jpg

Not as much clamping surface is required with the set screw type. I have been riding a SIR9 with this EBB at 250+ with no creaking or slippage issues.

Bicycle Rider said:
I don't have much experience with EBBs, so this is theory, but:

Won't the interface now be under more stress, seeing as the clamping area is narrower? Therefore, more prone to creaking and loosening? There is clearly a reason you didn't want to machine it down all the way to 2 inches even, say.

If it was me, I would have machined only the non-drive side of the eccentric and the shell, and kept as much material as possible closer to the centerline of the chainring.

Eric.
 

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Discussion Starter · #8 ·
reaming and shiming the cam makes a huge difference in grip. I figure that I will still have plenty. This is just a theory. It's nice to have a $250 frame that I can destroy. But I really think that it's going to be ok.

I will test ride the bike next week sometime and will update the wiki.

see also: http://www.pvdwiki.com/index.php?title=Shimming_Eccentric_Bottom_Brackets
 

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I actually looked at the Zion 737 SS frame, but the TT was too short for my tall self. The Niner started out as one of those "I'm just gonna build up a SS on the cheap to check it out" situations, and we all now how that turned out.
 

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pvd said:
son of a *****!



Totally missed that. good call. it seems to be holding. I will fix it when it fails.
I swapped out the HUGE bolts for tiny set screws. I think the BIG allen bolts lend themselves to overtightening (not saying that's what happened), and they weigh a ton.
 

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Mtn Biker Machinist
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Nicely done

PVD, while i have disagreed with some of your previous posts, this one rocks!

From one machinist to another, that is some nice work. Do you have the machines yourself, or is that done at someones shop? I am always looking for things to build/tinker with on my bike. I like your willingness to try things that most people would load their pants just thinking about! Let us know how it works out and holds up.

I actually own the same frame, but hadn't even thought about doing that.

Do you have a print for the arbor you wouldn't mind sharing? PM me and I will give you an e-mail to send it to.

Good work

frog
 

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teamdicky said:
I swapped out the HUGE bolts for tiny set screws. I think the BIG allen bolts lend themselves to overtightening (not saying that's what happened), and they weigh a ton.
Could it have been impact damage?
 
G

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No Need

aka brad said:
You'll leave these alone ;)

Brad
No need to mess with them. Ours are already 135g for the relieved version.
It appears as though the Zion shell is a constant ID all the way across. We drop the weight out of the middle of ours to maintain width and it gives frame builder less problems with distortion.

PVD, what is the OD of the Zion eccentric? Ours may just slide in there. Just curious.
Brent
 
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