karldub

I have an old Shimano Golden Arrow 2x drivetrain consisting of 52t and a 42t chainring (probably, haven't counted)
For a new bike I'm working on, I'm thinking about using this drivetrain and converting it to a 1x drivetrain.

Can I do the conversion by basically just omitting the larger chairning and just use the inner ring as my only chainring? Do I need new bolts and are there any "universal" bolts for 1x chainrings or are they brand specific?

FBinNY 

Assuming your crankset has typical double chain ring bolts then you need to buy a set of ,"track" chainring bolts because yours will be too long to use with a single chain ring. Track training bolts are pretty generic and inexpensive unless you want something fancy.

You might also want to consider moving the inner chainring to the outer position, as this generally offers better chain line.

Andrew R Stewart 

If you remove the ft der don't be surprised if you suffer from chain derailment off the ring when riding on rough surfaces. But simply removing one ring is a time proven way to get a 1x system. Andy

sean.hwy

I converted my Giant Revolt adv 2 from 2x to 1x. In my case the small ring was too small and the larger ring was too big. So I bought a single 40T chainring with the correct number of bolts and spacing. I also had to buy
these smaller bolts since I was only running single chainring now.

Rolla

Everyone I've ever known who has done this has ended up getting a 1X specific chainring with narrow/wide tooth profiles, or they attached some kind of chain retainer to the seat tube. Went on a ride with a guy who didn't, and his chain dropped nearly constantly, much to the frustration of the group (and him, of course).

ShannonM

Inside or outside, whichever gives the best chainline. The chain should run straight (ideally no deflection) to the middle cog. (On 6-speeds, I'd go for cog #3, since chain rub on the inside is harder to tune out, because of the spokes.)

Outside position looks better, but is, in my experience, less likely to work.

Either way, you'll need new chainring bolts.

I've run 3 1x6s. Liked them all. For an around town bike, a 6 or 7-speed 42x(13/14)-(26/28) is just about ideal.

--Shannon

PS: Fair warning... As good as the above gearing is for a roadie-to-townie build, a 42-45 or 42-39 half-step is even better. The required chainring costs about 30 bucks, and you have to lower your front derailleur and readjust. That's it.

Andrew R Stewart 

But half step gearing is so 1970s... Andy (trying to sound so modern but actually ran half step for many thousands of miles over quite a few years)

70sSanO

I guess a first question is, do you only ride the bike in the 42t now?

If you do, and there are no issues riding in all the freewheel cogs, then it kind of functions as a 1x setup already.

As others have said, you can remove the outer chainring and use 1x bolts.

You can replace the outer ring with a chain guard and replace the outer ring and use the current chainring bolts.

I was going to work on someone else’s bike and do a similar conversion. The night before they asked for a chain guard, so I took an old chainring, mounted it on a crank and filed the teeth off. A bit time consuming, but it turned out great.

John

bluehills3149

I've done a few of these conversions although most often to make a single speed rather than a 1x. I usually move the chainring to the outer position and get a new bottom bracket to center the chainline so the chainring more or less aligns with the middle cog (usually a 68x107 bottom bracket). I have never bought new bolts but just chopped the old ones down with an angle grinder but I can see that getting new ones for $10 is probably easier. I've also never had a problem with chains dropping off but it maybe because I have always used older cranksets which did not have ramps or profiling to aid shifting. These ramps and cut-teeth, (used on most bikes from the bikes 1990's +). are specifically designed so a slight nudge with the derailleur and the chain will transfer easily to the the next gear but absent a front derailleur will facilitate the chain dropping off.

grumpus

Ideally get a "narrow wide" chainring as it will improve chain retention, which might otherwise suffer from removal of the derailleur. You can make spacers so the original double bolts still work - just cut the tabs off a worn-out chainring. This can look neater than using a single ring on a double crank. Or you can make a chain guard from a worn-out chainring by removing the teeth.

jadmt

my chain has never come off.

grumpus

You need to go faster over the big bumps, while changing gear clumsily. :-)

tFUnK

Having dropped chains from riding off of the occasional curb even while using a narrow wide chainring, I would not recommend using rings with shift ramps for 1x or SS. Old school rings without ramps will work ok but I would just go with a narrow wide for peace of mind (even though it hasn't brought that to me).

robobike316 

Another option is to grind the teeth off of the outer ring and it will function as a pretty decent chaingaurd to keep most of the grease off your pants. This looks good as the ring matches the crank but obviously you cant go back with this mod.