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Discussion Starter · #1 ·
Hi, I’m looking to make my trek Marlin 5 a sort of all rounder bike, that would have a very high max gear ratio. I was looking at gravel bike drivetrains, but they didn’t have low enough gear ratios. So I was wondering if it is possible to run a drivetrain with a 50/34 crankset at the front (and still use a shifter that could fit on standard mtb bars), and use a 10 speed 11-42 cassette at the back? Is this possible, is there a long enough chain to make it possible? Would it be unstable? Thanks for any replies
 

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The crank won't fit. Too narrow of a q factor. Arms will hit the chain stays

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Not to mention spindle too short. And that 50t chainring is probably going to hit the chainstays, as well.

Beyond that, I don't think any derailleur can take up that much slack in the chain. I'm using a 50/34 crank on my gravel/touring bike with an 11-36 10spd mtb cassette and mtb long cage RD and it works fine, and I could probably get away with a bit wider range cassette, but 11-46 is WAY more and probably won't work.

Plus, I don't think you're going to be pushing anywhere close to that 50-11 gear. I certainly don't on my bike I put it on. This is the sort of gearing that most riders would use at the top end of a light road bike. Which has me looking at a crank with rings in a range I'll actually use.

FWIW, this really isn't all-rounder gearing. This is more or less gravel bike gearing. As described above, it's not going to work on a mtb.
 

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Discussion Starter · #4 ·
Not to mention spindle too short. And that 50t chainring is probably going to hit the chainstays, as well.

Beyond that, I don't think any derailleur can take up that much slack in the chain. I'm using a 50/34 crank on my gravel/touring bike with an 11-36 10spd mtb cassette and mtb long cage RD and it works fine, and I could probably get away with a bit wider range cassette, but 11-46 is WAY more and probably won't work.

Plus, I don't think you're going to be pushing anywhere close to that 50-11 gear. I certainly don't on my bike I put it on. This is the sort of gearing that most riders would use at the top end of a light road bike. Which has me looking at a crank with rings in a range I'll actually use.

FWIW, this really isn't all-rounder gearing. This is more or less gravel bike gearing. As described above, it's not going to work on a mtb.
Do you think something like a 30/46 and maybe 11-40 would work?
 

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This is a little bit of an interesting discussion. My grandson has a Marlin 5 (2016/orange) and it has a triple up front 24/34/44 i believe but only an 8sp out back. You could most like come up with something.

Is yours newer, have they changed...?
 

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Do you think something like a 30/46 and maybe 11-40 would work?
Chain wrap capacity for a Shimano 10-sp long cage derailleur is 43t so that would just work. An 11-sp
derailleur can handle 47t so you could easily use a 42t cog if you had that. As mentioned the challenge will probably be fitting that big of a chainring on and still maintain decent chainline.
 

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i don't think it can be overstated how cheap a marlin is. Tourney everything. Makes for some weird characteristics, like the 14-28t cassette.

A more sensible way to go about this is to replace the rear wheel (it won't last if you're putting serious commuter miles on it) with a freehub wheel and a cassette with an 11t sprocket. 42-11 is pretty tall; if that's not enough it's time to work on your spin.

Any more than that and i'd be wary of the hole where you end up replacing every single part piecemeal.
 
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