I am putting together a new Chromag Rootdown with a BB92 BB shell and Boost spacing in the rear. I picked up a wheels mfg BB to work with my 30mm RF SixC cranks but am wondering about chainline and how to get that set up correctly. I know others here must have the same type of setup...what works for you?
I'm pretty sure it is just a 3mm offset ring you need.
So like this : https://www.oneupcomponents.com/collections/switch/products/switch-cinch?variant=31481756865
I answered in the other thread as well. For your crank spacing you will need the RF spacing kit. This and a Boost NW ring should have you all sorted.
Thanks guys, much appreciated. Found this one too:
https://www.raceface.com/media/Crank_Q-factors_and_chainlines.pdf
Posted by: pedalhound
Thanks guys, much appreciated. Found this one too:
https://www.raceface.com/media/Crank_Q-factors_and_chainlines.pdf
Haha, my eyes literally glazed over reading that! Glad you found better info than mine!
Hah, yeah...that was me when I first started looking at it too. Then I found that the standard SixC was a RF136DH and it helped out. The BB that I bought did come with spacers, so now I am just trying to figure out if those will work or if I need to get the RF ones. I have never really thought about chainlines before....put a bike together and ride it, so this is all new. Damn boost and BB92 making me think!
Looking at that sheet and I think all I need are 1mm spacers...and to flip my chainring around?
What kind of spacers did the BB come with? Also, what kind of BB are you running? Are they 30mm spacers that will fit around your crank spindle? The spacing has to be pretty exact or you will have your cranks hitting your stays and/or you wont be able to tighten them enough to pre-load the bearings properly.
I can run a non-boost chainring on my 2016 Rootdown BA for sizes up to 30t. I’m not sure if the chainstay yoke has changed since, but it may be a non-issue.
Posted by: shoreboy
What kind of spacers did the BB come with? Also, what kind of BB are you running? Are they 30mm spacers that will fit around your crank spindle? The spacing has to be pretty exact or you will have your cranks hitting your stays and/or you wont be able to tighten them enough to pre-load the bearings properly.
It's the wheels mfg jobby:
This is what the guys at Chromag suggested.
You might have enough spacers there, its really hard to tell until you put it all together. Id go with what you have, and see if it works. Looking at that chart that RF supplied, it seems you only need 1.5mm on each side to space it properly, and your kit seems to have those spacers. Let us know how it goes! I assume if the guys at Chromag say it works, it probably will. They have probably installed a fair number of them :)
I think you may find the functional chainline better with a non boost chainring. Reason being it will center up around the 7/8th cog or so, gives you a nicer chain angle on the climbing gears where you put a ton of torque down. There is no need to center the chain around the 5th/6th cog IMO since I'm hardly in the highest 3 gears.
On my Rootdown BA and now the Primer I use a 28t ring (offset ~2mm to the middle ring) mounted to the granny mounts on my non boost 4 bolt cranks. Happy with the offset chainline.
Forum jump:
