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  1. #1
    cmh
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    Single chainring without a spider on a Surly Mr. Whirly?

    Quick question - looking at the Surly Mr. Whirly cranks because of the availability of 185mm. I run a 1x6 on my Niner SIR, and was considering the possibility of skipping the spider altogether, and finding a chainring in the 30-32t range that has the 5x58mm of the cranks. Yes, I know that's not a commonly available size, but I've contacted the guy at Home Brew and am awaiting a reply, but know of a couple other options as well. If it's possible, a bigger chainring (bigger than the commonly available 5x58mm granny gears that is) that mounts directly to the cranks would clean things up nicely, and reduce the number of fasteners needed.

    My biggest concern is that of chainline. Looking at the photos of the spider for the Whirly's, it seems that it mounts the bigger rings farther outboard, so chainline might be an issue. Can anyone who has the Whirlys comment on this?


    cmh

  2. #2
    cmh
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    Taking a closer look at this image:



    It looks like the middle ring mounts on the same plane as the spider's attachment to the crankarm, so it might just maintain the proper chainline. That's assuming this photo is viewed from the bottom bracket side of the crank.

  3. #3
    Former Bike Wrench
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    That is the SMALL chainring mounts on the same plane as the spider's attachment to the crankarm...not the middle/large chainring mounts

  4. #4
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    The OP is right. Think about it: the granny needs spacers under it, so there is no way it mounts in the same plane as the spider. I've got a set(5x110) running a single ring no less. Think of the spider as a chainring adapter for the middle ring. For 68mm BBs you'll need a spacer(2.5mm) under each cup to make it symmetrical. I'd guess the chainline to be about 43-45mm in that situation using the middle position.

    I'm using the outer position on a 68mm with a spacer on each side and it's nearly perfect with an Alfine hub. 185mm arms are in stock at and are available from any shop that orders through QBP.

  5. #5
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    Clearly O mis-read the OP's original post...however I was basically saying that the small ring mounted directly to the crank is in the same position as the spider is mounted...which is essentially what the OP said.

    My main concern would be the chainline...for a 1x6 you would not want anything narrower than about 50mm. 43-45mm would be too narrow for a 1x9 so for a 1x6 where the cassette is further outboard it would be way too narrow. I would also be concerned about any 30-32t chainring on that small of a bolt pattern. Using 185mm cranks, it seems like the chainring flex would be terrible...so you have to way overbuild a chainring. Could be done, but seems like a lot of trouble.

  6. #6
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    Hmm...just run it on the outside, right? Skip the whole direct mount idea and get a functional 104bcd.

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