Chinese Carbon MTB > 29+ & 27+
New 29+ Frame (CS-496) build
carbonazza:
We are starting the build of a 496 frame with a friend as a 29+
It is my first boost, so I start this build post with some doubts :)
* We will put an SRAM Eagle on it. Does it need the boost version of the crankset or is the frame already takes care of the 52mm chainline?
The groupset was bought complete, but I'm wondering the crank need to be exchanged.
The BB is BB92, and the width of the BB shell is... 92mm !
* It will be my first set of boost wheels too...
cmh sold me his 29" rims(42mm/36mm wide)
They finally landed in Belgium ( they transited in a friend's luggage from Phoenix AZ to Europe recently :o ).
From what I understood the 3mm offset goes:
* to the right of the front wheel
* to the left of the rear wheelIs it right? Does someone has a good article dealing with the specifics of building asym wheels?
Anything special I need to take care about?
Carbon_Dude:
I can tell you the crankset is not boost specific, that is taken care of with the chainring. You would need the proper Boost chainring that has the correct offset. As for the wheels, I've always just had wheels that were pre-built with 12x148 hubs rear, 15x100 front.
carbonazza:
The confusion comes that SRAM is providing both GXP versions... Boost and not.
To confuse us even more there are two kind of rings available, with 3 or 6mm offset.
As the offset goes inside, more offset means a smaller chain line.
And finding online resources about this is not easy.
SportingGoods:
I can confirm the info from Carbon_Dude, in a SRAM Eagle Boost group, the "Boost" is taken care of by the chainring. The cranks are standard. You can give it a try or just replace the chainring with the Boost version.
bxcc:
--- Quote from: carbonazza on February 24, 2017, 12:27:21 PM ---We will put an SRAM Eagle on it. Does it need the boost version of the crankset or is the frame already takes care of the 52mm chainline?
The groupset was bought complete, but I'm wondering the crank need to be exchanged.
The BB is BB92, and the width of the BB shell is... 92mm !
--- End quote ---
The others are correct. The standard offset it 6mm, boost is 3mm, and BB30 cranksets use 0mm offset. If you have a BB92 bottom bracket, definitely get the 3mm offset. With the BSA stuff, you can shift a GXP crank inboard by using a non drive side bb spacer so you can essentially use a 0mm offset ring with one NDS spacer and still be good. But with the BB92 bb, you can't do that. So you really should get the right offset chainring.
As far as the crankset itself goes, you just need a GXP BB92 bottom bracket. It will need to be pressed in but otherwise, all Sram GXP cranks will work once it's installed. My daughters bike has a BB92 bottom bracket and a Sram Stylo GXP crankset that was previously installed on my SS with BSA bottom bracket.
I am big fan of the Sram GXP setup. For me, it has been perfect and I have 5 bikes at home with cranksets that are completely interchangeable. Well, sort of, my daughters is a bit short at 150mm.
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