LaceTheSpaceRac

I can't currently afford to purchase a new chainset, but I want to convert my drivechain to a single ring up front for simplicity. So I'm wondering if I can achieve this by simply removing the front derailleur and using only the biggest ring, provided I use a narrow wide ring to help hold it in place? I already have a 42t narrow wide ring compatible ring I got second hand online, so i'd like to use this instead.

The chainset I have is the Praxis Alba double, which needs both rings in place to hold together, as the nuts pass through the big ring and then screw into the smallest chainring. For this reason I cannot just remove the redundant ring. The Praxis chainsets and BB are pretty good I think, so I also feel its necessary to buy a whole new chainset if I can avoid it as what I've got is still in good condition.

Obviously, one can do what I'm asking, but I would like to know if it's safe.

Thanks for your help

Iride01 

Maybe, maybe not. Can't you just put it in the ring you wish to use and then just forget about shifting it?

Safe is relative to your aversion to risk. If you want to be safe, then buy a new bike that is 1X instead of DIY'ing something that might be something less than whatever your ideal safe is.

If you have to make that bike 1x, then buy a 1x crankset with a chain line that is proper for your bike.

Welcome to BF.

LaceTheSpaceRac

Yes that's essentially what I will be doing. I think I wasn't clear – what I'm concerned about is that removing the front derailleur might also the chain to come off. But perhaps a narrow wide ring is use, plus setting the limit screws on the rear derailleur would solve that?

Buying a whole new bike just to go 1x? Definitely not. I'd just buy a new 1x chainset. Ultimately this comes down to cost vs safety. Seems to me like its either a case of, "it will come off", or "it won't come off", since its surely no different to having a 1x anyway? I'm no expert though, why is why I'm checking.

Thanks for the warm welcome

Marylander

I've been riding a double without a front derailleur for quite a while. I'm not taking rocky trails on it, although I do deal with some washboard dirt roads now and then. I've had no issues.

SpedFast

If you remove the front dr and set the chain on the sprocket (chain ring) of choice, it won't pop off. If you like the large chain ring but want to eliminate the small ring, can you use nuts/washers on the screws that come through the large ring to hold it on? Just a thought.

Iride01 

If you are wanting full use of the rear cogs then you may have an issue if you only change out the 2x to 1x. Without knowing what your bike is and the other components I will only say it might work for you and it might not.

A new bike might be almost as inexpensive as replacing everything you might need to replace to have a correctly working 1x bike.

70sSanO

Are your inner and outer rings using the same mounting bolt?

If they are, you can check the chainline to see if the outer or inner position lines up closer to the center of the cassette.

If they are off-center by about the same, just use the outer.

John

tFUnK

You can remove the second (unused) ring and just use thinner chainring bolts (designed for SS or 1x). Sounds like you already have a narrow wide single ring you want to replace the current rings with, so why not do it properly. You definitely do not need a whole new crankset just to go 1x if you can just remove unwanted rings on your current cranks.

OTOH, I've ridden triples in the middle ring as a 1x. Works fine.

mitchmellow62

It seems to me that converting a triple to 1x by using the middle ring would give the correct chain line. If you convert a double the chain line will be off no matter which chainring you choose to keep. Perhaps deciding what rear sprockets you will use most could help in the decision. It will be minor and I think either position will probably not be much of an issue.

himespau 

If you're worried about your chain falling off, chain catchers are cheap and effective.

GhostRider62

1X rings have a special tooth pattern to help retain the chain, the teeth are wider and narrower with seemingly a small offset.

I put a 1X ring on my bike. Initially, I kept the FD on to make sure the chain would not derail. Now, I am confident in it and took the FD off.

I would test whatever you decide. Keep the FD or chain catcher on. Getting out of the saddle and having the chain derail would be interesting

MNBikeCommuter

I've been doing this all winter with no problems. It reminds me of a story someone posted back in the days of Usenet glory, about a friend of his. The friend saw no need for a front derailleur. He'd just reach down, grab the chain, and put it on the appropriate chain ring. His left hand bar tape was a pristine white, and the right hand....

Bike Gremlin

If you don't have a way of moving the chainring further inwards (towards the bike), you might end up with a chain severely crossed when using the largest few rear sprockets.
If chainring's position on the cranks can't be altered, perhaps use a shorter axle (for square taper and the likes), or fewer spacers (for Hollowtech II) etc.

It is safe to ride - just the chain and the chainrings might not last as long. Perhaps a bit more risk of snapping the chain if your chainstays are relatively short so the chain's angle is more severe.

To prevent the chain from dropping, it's a good idea to use a narrow-wide chainring designed for 1x drivetrains - you have that so that's good.

A rear derailleur with a clutch might not be necessary, depending on how aggressively you ride on rough surfaces (bumps).

P.S.
The way I see it, 1x systems are solving a problem that doesn't exist. Especially when altering the drivetrain that wasn't designed as a 1x. I doubt you'll be saving any money in the long run, and how complicated is it to operate the front shifter, really?

If you ride in such mud that it gunks up between the FD and the frame creating problems, then it makes a bit more sense. Or if every gram saved is extremely important. Apart from that, it can be a fun, perhaps more/less expensive project (if you are not willing to spend much, it's another reason not to go that way, from a perfectly functional drivetrain) with questionable objectively measurable gains.

prj71

As long as you have a narrow wide chainring you won't have any problems. I did this same conversion on a 2x in 2015 on a fat bike. The chain never popped off once even when I took it on rough trails.

tFUnK

Exactly, going 1x your chainline will not be optimal most of the time (in theory), regardless of whether the ring is inside or outside of the spider. I ride my climbing gear more than I do my descending gear, so my ring is inside of the spider.

That said, it's not an issue in everyday use. I can go in any gear, including the extremes, without problems. For some, 1x is simply easier to use, despite the implications on drivetrain efficiency and wear.

jp911

It will work fine if you get the chainline right, which can usually be achieved with spacers (either at the bottom bracket-crank interface OR washers where the chainring bolts to the crankset). I've done this on a few bikes and the narrow-wide chainrings help a lot, and if you plan to get really rowdy a chain catcher or clutched rear derailleur will help.

GamblerGORD53

1x is just a lame fad. Get over it. How hard is it to get a 2x to shift properly?? You would lose at least 1/4 of the gear range.
Use the small front gear with the big 2/3rds of the back cogs. The opposite for the big front gear.
NEVER use the last 3 cogs crosschained either way. I never actually used a 2x, 3x sucked with constant double shifts. Only IGH for me now.

bboy314

This kind of seems like it’s making a good argument for 1x…

SoSmellyAir

The aspect underlined above is incorrect with respect to a 2X to 1X conversion.

Assuming that the bike had been correctly setup as a 2X, the ideal chain line is mid way between the two chain rings. One cannot achieve this chain line by adding washers between a single chain ring and the spider of the crankset, because doing so merely increases the distance between the chain ring and the ideal chain line.

Instead, one can either (a) increase the distance between the spider and the bike so that mounting a chain ring inside the spider would put the chain ring at the ideal chain line, or (b) decrease the distance between the spider and the bike so that mounting a chain ring outside the spider would put the chain ring at the ideal chain line. (a) can be done (like you said) with a spacer inside the crank arm. (b) can be done by reducing the spindle length. I think (b) generally looks better.

Bike Forums - View Single Post - Converting Trek FX2 to 1x

jp911

Not always true. It depends which side of the spider the 1x chainring attaches. If it's on the "outside" where the large chainring of the 2x sits, then you're correct in that the chainline would increase with spacers, but on the "inside" and it can be spaced in if needed.

SoSmellyAir

First, do you agree with what I said above, that assuming that the bike had been correctly setup as a 2X, the ideal chain line is mid way between the two chain rings?

If so, I don't see how what you said above can be the case. The smaller chain ring mounted "inside" the spider in a 2X setup is already inboard of the ideal chain line. If you replace it with a 1X chain ring and add washers between the 1X chain ring and the spider, the new chain ring would be even further inboard, i.e., even further away from the ideal chain line?

jp911

I understand your point, and I think the wild card is the narrow-wide chain ring being used as some are spaced to correct for chainline. I'm weighing in with my personal experience, and the use of spacers at the bottom bracket and the chainring interface with the spider can be used to adjust chainline. In one case, I ended up using 4 x 1mm spacers (one on each arm) to move a chainring inboard (105 crankset with a Wolftooth narrow-wide chainring) to make a small adjustment that ultimately hit the ideal for the setup.

So far, I've done this on several older MTBs using 10-speed Shimano derailleurs and 4 bolt crank arms, a 90s Cannondale MTB converted to 1x for commuting, 2 11-speed Shimano gravel bike setups, and more recently on a cross bike using a mix of Shimano road and mountain parts. So, I'm not a shop mechanic or a race mechanic, but I've taken this on a few times. And, every time I've had to make fine adjustments using spacers to really nail the chainline.

SoSmellyAir

I see. I think what you are describing is installing chain rings for a boost chain line on an older (i.e., non-boost) mountain bike? I am not a mountain biker so I have no experience with that.

tFUnK

Agree in principle but inconsequential in practice. A 1x converted from a 2x should be no worse overall than cross chaining on either ring of a double.

70sSanO

Just wondering…

If usage is equal, is there more cog wear with a 42t outer to a 32t (lowest) cog or more with a 42t inner to an 11t (highest) cog?

Or does it not matter?

John