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MTB 29er Gearing Advice


MadManMike

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Morning chaps!

I'm looking to switch my gears from the standard 3x9 to 1x10 or 1x11.

I'm a total noob when it comes to gears, so I'm looking for some advice on what to buy, otherwise I'll end up spending cash on something that isn't compatible.

I'm not looking to spend silly amounts, but then I don't want something crap either.

Any advice appreciated!

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Stick with 9 on the back and just chuck a narrow wide on the front. Base the size of the chainring on your anticipated requirements, do you find you're in middle or top ring most of the time? Ideally your chain should be running on the middle of the cassette for your cruising gear but a compromise is often required to still allow climbing.

 

I'm running 32/11-34 9 speed and don't struggle with low enough gearing for climbs,  however it is a little low for road work and I spin out at about 28mph. On general flat trails and road I'll cruise in 8 or 9 so in reality I could go up to a 34/11-36 to gain some top end but still keep the same nominal climbing gear.

 

 

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I'm normally in the middle ring. I used to drop to the lightest ring I could for climbs, but I stick to middle ring's lightest gear these days.

Good shout changing the front only, much better for my wallet!

I don't know how gear ratios work, but I'm guessing a ring kind of in between the middle and lightest would be best, to still allow steeper climbs?

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What's the lowest gear you ever tend to find yourself in at the moment? Getting something that'd put your new "first" around that ratio would be about right in that it'd retain the Climbability for demz hillz, though you'd lose out a little on top end. That said, if you're beyond spinning out rage then you're likely going downhill and, if the impression I've got of what you tend to ride is correct, you're probably not too worried about losing that 1mph in those scenarios?

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Next thing you'll need to worry about with a single front ring is keeping the chain in place.

Options are, top guide and narrow wide. Narrow wide and bash guard. Normal ring with top and bottom guide. Narrow wide with clutch mech...

I don't care what anyone says about narrow wides, you'll eventually drop a chain. Kicking on your pedals with no engagement = knees to the bar.

Edited by Ross McArthur
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Yeah I was thinking I'd need some kind of mech, I don't know the differences, but I've seen those tensioner type things that attach to the frame along the chainstay. Top guide and narrow wide would be my preference I think, unless there's any reasons why not...

Luke - correct, I don't normally max out the gears going too quickly so that's not a problem. Majority of my riding is trail centres, so if I can climb that's good and then on the downhills I'd never be pedaling in the 9th gear so that's fine. The heaviest ring I never use, the lightest ring I only use on unusually steep climbs (which I tend to walk up anyway, f**k climbing that kinda stuff!)

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I would go up 2-4 teeth on your current middle ring, stick with same cassette and your legs will soon adjust to the extra load when climbing.  I would say that my climbing ability is nothing more than acclimatised hip flexor muscles and enough lungs to keep them fed with oxygen.

 

I wouldn't worry about dropping the chain right away,  knowing the level of your riding (no offence) I think you'll be fine with just a normal mech and a narrow wide ring. I ran my old xt mech and my wolftooth ring for months and the only time it dropped the chain was after an otb into a tree. The only reason I got a clutch mech was because my old one died and getting one quietened the drivetrain considerably; never a concern about chain security.

edit: I would have happily ridden the entire of the beast without a clutch mech.

 

 

 

 

 

 

Edited by forteh
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Not really much for me to add after what's already been said. I reckon you'll be aiming for something like a 32t on the front. I've ran 32t front with ten speed 11/36 on the rear for a year or so and that was an ideal set up for here up north where there's big hills ha. I dropped to 30t while I was in whistler but that's because xc involves riding up a mountain ha. Even with the 30t up front it didn't lack too much for high speed laps in the bike park.

Having said all that my new ride has sram 11 speed which is a very impressive setup so far.

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Ace, cheers guys!

I'll have a look around for a decent ring then. My main reason for thinking about a guide of some sort was more to stop the horrendous slapping noises - my gear components make a racket when I'm crashing over red trails.

If not a chain guide, any ideas for sound deadening a little?!

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A clutch mech makes things become a lot quieter obviously by not allowing the chai to rattle about as much. Running a triple setup generally means a lot of noise cause of the longer chain mostly amongst other things. 

Covering your seat stays and chainstays can help make bikes a whole heap quieter too. Wrapping them with an old inner tube can be a cheap way of doing it. Or layering up some bar tape on there followed by another layer of something like stronger tape can look a bit neater.

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Yeah I definitely need to get some kind of chainstay protector, if not for noise but aesthetics - it's pretty battered.

How short can you go on the chain before gear changing becomes a problem?

Like you say, having three rings means my chain is pretty slack, so I was hoping to make it a fair bit shorter for just a single ring but I'm not sure how the mech would work with a short chain.

These questions are the result of having several different DMR jump bikes over the years, I was always anti-gears :)

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To get the right chain length I've always gone with the technique of putting the chain on both of the largest rings (avoiding the rear mech) and adding two full links to that chain length. It's usually there or there abouts with that method.

So at the moment your chain is likely optimised to go in both of your large cogs which will be a big spread. 

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Ah ok, that makes sense - yeah, if you're in two smaller cogs it's pretty ridiculous in length :)

One last question, my cranks are Shimano FC-M430, 44 x 32 x 22T, 175mm, what type of chain ring will fit? I don't want to order the wrong thing, which I normally do when I impulse buy!

Thanks for the help mate.

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I'm pretty certain they are 104bcd. So basically you'd need a 104bcd front sprocket which would sit where the middle ring is. Seeing as you have a 32t centre sprocket I'd suggest going for a ride and using only the middle ring and see how you get on with it. 

You may also need some different chainring bolts that are narrower. 

What rear mech do you have?

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