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Hey everyone, I have a Trek Marlin 6 with a 3x8 system and have been thinking about ditching the 3x system and converting it to a 1x8 system, so i can get rid of the front derailleur all together. Now that I am starting to trail ride a little bit more, (no crazy trails or anything) I want to go to a 1x system just for further simplicity, and because I really don't use the front derailleur anyway. I've started looking at some chainrings and cranksets to replace the current ones I have such as these:

https://www.chainreactioncycles.com...unt-cinch-narrow-wide-chainring/rp-prod113269

https://www.chainreactioncycles.com/us/en/race-face-aeffect-single-chainset/rp-prod146212

These are some things i've been looking at, mostly by race face. I'm first off wondering if these would even work with my current setup. Next what size chainring would i need (30, 32, 34 tooth...) and what size cranks I would need (170, 175mm)? Lastly, would I need to shorten my chain or buy a new one altogether? Thanks!
 

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How many teeth are on the front chainring that you currently ride most? One of the considerations when trying to go from 3x8 to 1x would obviously be giving up a heck of a lot of range. Most modern setups are at least 11 speed 1X and the wide range ability of the modern cassette/derailleur pretty much negate the need for a front derailleur. With a limited 8 speed setup you could either be perfectly fine (if it's pretty flat where you are) or end up in some trouble if it's mountainous where you have wide ranges of speed.

That said, somebody with some knowledge/experience with Trek will have to chime in about the crank fit. You'll obviously have to buy cranks that fit your existing BB in terms of spindle diameter/width. Crank arm length will largely be a matter of personal preference. As for the chain, assuming you install a single chainring that is no bigger than the biggest current chainring or smaller than the smallest current ring and leave the same cassette then it will work fine. If you end up somewhere in the middle then you could probably stand to remove a link or two since it will no longer have to accommodate the larger chainring.

It may end up being less work/more cost effective to look at a new-to-you used bike that is already set up 1x10/11/12 as they're pretty widely available these days
 

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I've done that exact frame as a 1x10 for my daughter (was my first frame). Need a BSA threaded Bottom Bracket that fits the crank. Could certainly use the parts you chose.

If you do that route, I would do the 30t chainring, as with a limited cassette range (I think it has like a 11-32t cassette stock), you'll need the smaller ring to maintain any real climbing ability. I usually run 170mm length cranks, though 165mm are getting some popularity.

I would recommend swapping out the derailleur, cassette, and shifter to a 11sp at least if you have the budget. The cassettes and chainrings are better suited for a 1x.

https://www.backcountry.com/sram-nx-eagle-dub-groupset
https://www.competitivecyclist.com/sram-dub-bsa-bottom-bracket
That's $375 and $38, but they give 20% off first order. Would cost you $320 and you'd be 1x12 all in. The raceface crank, chainring, and bottom bracket would have you at $200 roughly, so for $120 you'd be completely set.

Now, if you live outside the USA, this is a great drivetrain. Shimano stopped many retailers outside the US from selling their stuff to USA.
https://www.chainreactioncycles.com...0sp-drivetrain-groupset-builder/rp-prod136653

Another option is to search for a take-off drivetrain on eBay. Lots of bikes come spec with NX and people upgrade to X01 or XX1, so the shops take the stock bits n sell em. Brand New stuff just no fancy boxes.

Hope this helps.

Sent from my GM1915 using Tapatalk
 

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Why are you replacing the crankset? A narrow-wide chainring from Wolftooth or Race Face or even Garbaruk (if you need something really custom), and a set of short chainring bolts will give you instant an instant 1x drivetrain.
 

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If this is what you have -

you have to replace the crankset for that conversion, the chainrings are riveted together.
I would save a little and replace everything to an SLX 11 speed if you're serious about taking the bike off-road. I will detail an upgrade of that bike on a video soon, starting with the fork for now -
 
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