iamtim

So, long story short, I grew up racing BMX, switched to road cycling (geared and fixed), got hit by a car and had a couple of other close calls, recently decided to get out of road cycling before I got flattened. I got into "big wheel" BMX (24"/26"/29") which was fun, but I realized I missed distance riding. I've got lots of local trails around me here in SoCal, so I decided to get a mountain bike and hit the trails.

I picked up a Motobecane Fantom Expert (29" hardtail) from BD, got it all setup, took it out for a couple of rides on the Fullerton Loop. It was great, but for the riding I'm going to do, I wanted a 1x setup. Coincidentally, Box Components hit me up with an email saying that the Box Three 1x9 setup was back in stock; I ordered it, received it, and installed it. It rides well, I'm happy with it.

Here's where I need a bit of advice: I haven't yet gotten a crankset. It's sitting pretty well chainline-wise on the middle ring (32t) of the stock triple crank (Shimano Tourney TX). I had thought I could just strip the small and large chainrings but they're riveted on. So I need a fairly inexpensive 1x9 crankset with a 30-32 tooth chainring. Here's the kicker: it's got a square-taper BB, and having just purchased the bike and the drivetrain conversion, my CFO isn't going to be happy with another couple-hundred-dollar expense. So I'd like to get a square-taper crankset for now, something relatively inexpensive, and then upgrade cranks and BB to something nicer later. This is, like, an immediate and interim fix.

So, what are my options? Any recommendations? If I can't find an actual square-taper 1x9 compatible crankset, could I just pick up another triple and strip off the large/small chainrings (assuming a good chainline)? Or am I looking at complications I'm as-of-yet unaware of?

FWIW, there is no chain-rub on the inside of the large chainring currently, even when in the smallest cog. So I'm good there.

Thanks!

Kapusta

I would just pick up whatever square-taper triple crank that you like and use the middle position of that. I've done that many times. Loose the small ring, and you can either use a cheap bash ring on the outside or just get some shorter chain-ring bolts and leave it empty. For an inexpensive bash, try BBG.

Might want to invest in a Narrow-Wide chainring as well.

Charliekeet

Did this recently to my son's bike - 1x9 using the existing Deore LX triple crank. Did the narrow-wide ring thing as Kapusta suggested and we're having zero issues with retention - I got a Wolftooth ring, and even without a clutch rear derailleur, it's good. At this point, the outside is empty, but those BBG guards look like a better idea than the cheapo Amazon ones (and less dough than the Raceface or MRP ones, for example).

Happy Feet

Or get creative with the angle grinder and turn that outer chain ring into a bashguard.
I swapped out my middle ring for a Blackspire 42T and kept the small ring as a manual shifted bailout granny gear. 1x8 Deore LX.

c_m_shooter

Just lock the front derailer in the center position with the endpoint adjustments and leave your existing cranks on there. That is how we did it in the old days.

iamtim

That's a really good idea.

Happy Feet

I made that bike to be a gravel bike / commuter and for the most part was ok with 42 / 11-40 but decided to keep the granny as a seldom used but available bailout for long sustained hills. The Sunrace 8 speed wide range cassette fit the deore xt without a wolfstooth but just barely and I have since swapped it out for an 11-36, moving the 40T to another build with a longer cage derailer.

The chain ring bash guard was moderately labour intensive. There was a thin circular line beneath the teeth that acted as a guide for grinding and aluminum goes fast. I used oven cleaner to remove the black anodizing and buffed it a bit.

70sSanO

I turned an outer chainring into a bash guard by mounting it onto an old crank on an old frame. I filed off the teeth as turned crank with a pedal.

Talk about labor intensive. It was not just a poor man’s lathe it was a well below the poverty line lathe. It did turn out really good, but never again.

John

Kapusta

i’ve considered DIY options in the past, but with BBG bashguards going for around $20, it just never made sense.

But your method sounds like a great idea if I ever go the DIY route.