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Discussion Starter · #1 ·
I am excited about going to a single ring this year and am in the process of rebuilding my IF Planet X. Got all the parts, I thought, but when I went to complete the build, a few issues came up that I need some help with.

Here's the rub (literally). I have an older IF running an Ultegra 10 drivetrain (compact crank). Last year, to get a 46t/36t to clear the chainstay, I had to place a 1mm spacer on the drive side cup. No problem, worked fine. Now, if I try to put 2-3mm of spacer to allow the 42t ring on the inner side, the spindle is not long enough to secure on the non-drive side. Won't work.

So, that gets me installing a 42t ring on the outer, with spacers and a chainguard outside of that. My question is for the inner protection. An inner guard won't fit. Does anyone run a dog-fang, or other device that has the reach to get to the outer ring? Are there any other concern I should be looking at?

Thanks.
 

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Your CX frame can't clear a 42T inner?

I would look at the Rohloff or new-this-year Paul Components chain retainers that work like a "dumb" FD to keep the chain from jumping. Or just a regular FD adjusted into position with the limit screws.
 

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Your chainline won't be great for the 42x27 or whatever you are running, but otherwise it is fine. Get the n-gear jumpstop, it will reach to the outside. This is a better set-up in my mind than running cranks that aren't 'centered' under your saddle.

The other option is to crimp the chainstay using a couple of 2x4s and a vice. it's steel, so you can do it, but.....
 

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I had a similar issue on my Vicious and ended up putting my octalink ultegras back on with an XTR bottom bracket. The extra 4mm of spindle length gave me just enough clearance to eliminate the rub. If I go back to my FSA cranks, Ill likely run them as far inboard as I can, then run the ring on the outer position with a couple spacers and then the guard. I also use the N-gear and its a far better product than the dog-tooth style guides out there.
 

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dankilling said:
I had a similar issue on my Vicious and ended up putting my octalink ultegras back on with an XTR bottom bracket. The extra 4mm of spindle length gave me just enough clearance to eliminate the rub. If I go back to my FSA cranks, Ill likely run them as far inboard as I can, then run the ring on the outer position with a couple spacers and then the guard. I also use the N-gear and its a far better product than the dog-tooth style guides out there.
chain line is measured from the center line of the gap between the small and large chainrings (doubles) or from the center line of the middle chainring on a triple.
Thus to get proper chain line (or darn close) you need a triple bottom bracket.

The suggested XTR is a great suggestion.
 

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Discussion Starter · #7 ·
Thanks for the comments

Thanks for the suggestion. I may start with the n-gear thingy since I have all the other parts. It was a bit odd from the start when I had to shim the 36t ring. I guess the older spindles were just longer. Fortunately there is plenty of time to work this out.
 

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I know I'm a few days behind the crowd with this response, but I thought I'd support the N-Gear Jumpstop recommendation. I just put one on my mountainbike when I converted it to a 1x9, took it out on some very bumpy trails, and had no issue at all with the chain coming off. On top of that, it's a quality piece, very inexpensive, and I think it's the best looking option that I've seen. Good luck!
 

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Sickitty said:
I guess the older spindles were just longer. .
Square tapers offered more spindle lenght options, but they weren't spaced further from the frame using the 'correct' size. All doubles should be spaced with 43.5mm of offset. I'm guessing it's a 'defect' in the frame.

After thinking about this for a couple of days, and considering you have plenty of time, it may be worth some high res pictures and then a call to I.F. A cross frame, especially one of that caliber, should be able to run a 42 on the inner position without a shim. It might not allow for an inner guard as well, but at the least the ring should fit. You certainly shouldn't need a shim for a 36 inner...
 
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