Triple crank to 1x
 

I am thinking of a winter project to "rebuild" an older Specialized Rockhopper MTB. I am trying to minimize my research time by finding if it is compatible to completely replace the triple crankset (including the bottom bracket) with a 1x something (also new cassette, chain, etc. etc.)
Thanks for any and all insights!

i converted my early 90's mtb that had XT 3x7 to 1x8 using a box 4 8speed kit. works great. I used my original bb because it is a phil wood. I also use my original xt crank and am just running a single 40 tooth chain ring on it. used problem solver chain ring bolts and perfect chain line.
https://www.jensonusa.com/Problem-So...EaApb0EALw_wcB

To get a reasonable gear range, particularly a suitable low gear, you will have to go to a much wider range cassette and your current rear derailleur may not handle the larger big cog. Also, what is your current drivetrain, 3xX? If X is 7 or 8, you may not find cassettes with a wide enough range and/or the interior gearing gaps may be unacceptable. Upgrading to 9 or more will require new shifters and maybe even a new freehub. There is more to 1X than just deleting chainrings.

My own experience in this thread; most relevant portion starts at post #17:

Converting Trek FX2 to 1x - Bike Forums

Two other threads in which I had participated here:

3x to 1x conversion - Bike Forums

Ain't too proud to beg: 1x conversion hopes - Bike Forums

Microshift Advent (9-speed) or AdventX (10-speed) might be good options. We've done this on a few bikes now. I wound up going from 3X to 2X on one old mountain bike, and that worked fine, too. Microshift makes decent, solid-quality derailleurs and cassettes at reasonable prices.

Super helpful! Thanks.
If only you were closer to the Adirondacks--i'd buy you a beer to come over and do it for me. :lol:

I have been looking at Microshift actually. Good to know they have a decent review!

Appreciate the advice...and as I am in the Adirondacks of NY...the hills.
Bike has been hanging in the garage for about 10 years so replacing entire drive train is probably a necessity which will (I think) solve ratio's and derailleur issues.

It is not difficult. You just need the right tools, patience, and time. You can do it!

I have no experience with Microshift shifters except for a bike (for my son) which I had to return (because it was too big). They shifted just fine on my work stand, but online documentation on adjustment is (as expected) more sparse than Shimano. So if you can afford the difference, I would go for Shimano, simply for the fact that both printed and video instructions are more readily available.

Why does the drivetrain need to be replaced? Is it rusted or otherwise damaged? If neither, start with just a thorough cleaning and lubrication, then calibrate the derailleurs

I would say tires, brake pads, cables and cable housings are more urgent candidates for replacement.

What is wrong with the gear ratio?

You may need a narrow wide chainring to keep the chain from falling off as well.

Only caveat in the gear ratios is whether the freehub body is 7 speed or 8-10 speed.

If it is a 7 speed you'll need to run 8 of 9 cogs with 9 speed shifters, or 9 out of 10 cogs with 10 speed shifters. The potential issue with 10 speed cassettes is whether the cogs are on a carrier/spider or individual. I've done a mix-n-match of cassettes with individual cogs to get the range and gaps I want.

If you are running 8+ speed cassette now it is more of a plug and play going to a 9 or 10 speed drivetrain.

John

Edit added: I'm assuming if it is a 7 or 8-10 speed freehub body that is is the Shimano "c" freehub body that accepts an 11t cog. If it is an older UG/HG there is an issue with running an 11t; which is pretty much the norm for the first position cog.

A lot of rust and weight savings was my general concern for the triple cranks. Secondarily, upgrading components where my budget allows.
By ratios I really meant making sure whatever I do upfront translates then into shifting, cassette, and derailleur compatibility.

I'd suggest running your current gear range through something like Bike Calc's gear-inch program, so you have an idea of how your proposed new 1x will compare.

If you're worried about climbing hills, start with your cassette, and whatever the big cog is, and adjust your chainring size to get the right value for that 'granny gear' Depending on where it comes out, you may be able to use the existing crank, just bolt the new 1x ring in place of the middle ring using 'single-speed' chainring bolts. It should provide an acceptable chain line without having to mess around with spindle length and offset like a full crank / BB swap.

​​​​​​Keep in mind, that you're probably going to loose a lot of top end speed running 1x on a 26" bike, due to the wheel size, if you're trying to preserve decent climbing gears.
I did a simple 1x on an old MTB I set up as a city 'scrambler' (1x6, because SunTour) and even with a 40t ring, it spins out a lot easier than I expected.

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All I have to say is that if you live in a mountainous area converting from a triple crankset to a single front ring is a terrible idea, especially if you only have 7 or 8 cogs in back

​​​​​I agree, but not for the reasons I think you have. The OP bike in question is an old Rock Hopper, which, I suspect OP is trying to make like a modern MTB.
A 1x makes sense if you ride trails and singletrack where you're always in the deep gears, but if you install the same fitments from a modern MTB on to a 26er, you can end up with a way over-geared bike that can climb a tree, but can't get out of it's own way on a fire road.
You got to know what gears you are using and how your new setup compares before you start throwing parts at it.

for riding around at 13-16 mph and doing 25-30 mile rides on easy trails and mups this has been a blast. super simple and light. Not like I need closer ratios as not looking to set any records. shifts are crisp and quick from top to bottom and vise versa. When I do longer rides I do like my 1x11 better but for just messing around this works great.

https://cimg3.ibsrv.net/gimg/bikefor...3ea45aac35.jpg
https://cimg5.ibsrv.net/gimg/bikefor...964cf78965.jpg
https://cimg6.ibsrv.net/gimg/bikefor...dfc05f9c77.jpg