It's a question that many riders have. It can lead to constant debates and confusion on the Internet. Here’s our POV and breakdown.
Both work great with some slight differences.
- 3/32” drivetrains are slightly lighter, quieter and more forgiving to an out-of-alignment chainline.
- Contrary to popular belief, 1/8" drivetrains are not inherently stronger or more durable than 3/32". You can find 3/32" chains that are just as strong and durable as 1/8".
- 1/8" tends to have more availability of some components - chainrings and cogs - for future upgrades and changes.
- 3/32" drivetrains are more versatile as they can take 1/8" and 3/32" chains (including any 6-8 speed chain).
- 3/32" has a sleeker look while 1/8" has a more robust look.
- 1/8" may provide more track "cred" but riding fast provides even more cred. :-)
3/32" and 1/8" drivetrains are basically the same design except for the nominal width of the chainring, cogs and inside plates of the chain. For example, 3/32" drivetrains have about 3/32" wide chainrings and cogs** with a chain width that fits those components. 1/8" drivetrains have about 1/8" thick chainrings and cogs** with a chain width that fits those components. Everything else should be the same - chainring and cog diameters, tooth size, the chain pitch (distance from roller to roller), chain height, etc.
**Tech / Nerd Note: For clarity, nominal means the standard dimension to design the drivetrain around, but it doesn't mean the exact width (ie thickness) of the chainring or cog or the exact internal width of the chain. Rather, the chainrings and cogs are slightly narrower and the chain width is slightly wider so 3/32" is roughly the gap between the teeth and chains on both sides. See the illustration below.
1/8" drivetrains has a similar relationship where the chainring is about 15/128" thick at the base and and the chain internal width is about 9/64". See below for some caliper measurements for reference.
3/32" vs. 1'8" chain width comparison
3/32" vs. 1/8" chainring width
From a design standpoint, 3/32" and 1/8" chains are basically the same except for the width between the plates. Some people believe 1/8" chains are inherently stronger or more durable due to their width. However, there is no strength or durability advantage to being wider. Rather, 1/8" chains tend to be marketed as more heavy duty - with thicker plates for example - given their track use. However, there are plenty of 3/32" chains out there - from the more basic KMC K1 to e-bike specific 3/32" chains to the higher end Izumi Super Toughness 3/32"- that provide the same "extra strength" and durability advantage in a 3/32" format.
3/32” drivetrains are the traditional road standard for chainring, cog and chain width. This narrower standard is better for multiple gears as the chain is more flexible for shifting and the changing chainline on multi-speed gears. It also allows you to fit more cogs into a smaller space (like the rear cassette) given the narrower sprockets. However, 3/32” drivetrains are also used in track racing and is preferred by some pros due to its lighter weight.
1/8” is a traditional track racing standard for chainring, cog and chain width. The thicker components, including thicker plates on some 1/8" track chain, allows for a slightly stiffer, stronger and more durable drivetrain. However, those differences may be inconsequential for most riders (and at the expense of weight, noise and forgiveness above).
Let’s start with an important note on strength (and dispel a myth). Both 3/32” and 1/8" drivetrains, assuming you have quality, well-maintained components, will be plenty strong for almost any rider. The “weakest” point is the chain, but even the lightest and narrowest of chains can take 12x the force any rider would put on it. For example, a standard 3/32” road chain can take about 8000 newtons of tensile (pulling) force before breaking. The strongest rider at 400+ watts slamming on the drivetrain might hit 600 newtons. Not even close.
You can add a heavy duty chain to both 3/32" and 1/8" drivetrains for "added strength", but you are not really making a difference. If anything, it can help with durability (see below).
3/32” is slightly lighter as it has a narrower chain (less roller and pin material) and a ~1/32” thinner chainring and cog. For perspective, let’s compare the same Andel chainring, KMC K1SL chain and EAI Deluxe Cogs in 3/32” and 1/8" for an apples-to-apples comparison.
3/32” 48T chainring, 17T steel cog and 100L chain = 465g
1/8” 48T chainring, 17T cog and 100L chain = 520g
3/32" drivetrain weight
1/8" drivetrain weight
There is a 12% or 55g difference. Yeah, it is pretty small, but it may matter to some.
Similar overall. In theory, a 1/8” drivetrain with a slightly thicker chainring and cogs and a stiffer chain, would be stiffer overall, but there is no data to support that it has any consequence.
Durability / Chain Stretch
Similar overall. As mentioned, a heavier duty chain can provide longer durability and they tend to be more marketed or available with 1/8" chains. However, you can find heavy duty 3/32" chains that provide that same benefit (with a little less weight).
3/32” will likely be a little quieter as it is more flexible and forgiving especially if your chainline is off. However a 1/8" well-maintained drivetrain with a close-to-perfect chainline may be just as quiet too.
3/32" will be more forgiving to an out of alignment chainline as the narrower profile can flex more. (Chainline is how well the chainring and rear cog line up. It can get off as different components - BBs, cranksets, hubs, etc. - can lead to differences up to 3-4 mm.) This will also slightly reduce wear on components as there will be less friction between the chain and chainring or cog.
1/8" chainrings and cogs tend to be more widely available than 3/32” given it is a track standard. So, if you believe you'll be making lots of gearing changes, you may want to start with a 1/8" drivetrain. However, 3/32" drivetrains probably have more chain options as you can use both 3/32" single speed chains and any 6, 7 or 8 speed road chain given they are equivalent.
Interchangeability / Versatility
An important note on compatibility: You can use an 1/8" chain on a 3/32" chainring and cog (as it is wider), but you can't use an 3/32" chain on an 1/8" chainring and cog as it won't fit between the chains. Some people believe that 1/8" chains on 3/32" drivetrains don't work well or wear faster, but we haven't seen that as an issue (Remember it is only a 1/32" difference).
This means a 3/32" drivetrain does provide more versatility. You can use any 3/32" or 1/8" chain on the drivetrain. Plus, if you ever break a chain on the road, you are more likely to come across a 3/32" replacement on the fly (given it is the road standard) than a 1/8" replacement.
Street or Track Cred
Some people believe you need a 1/8" drivetrain for true track or street cred. That’s cool if that’s what’s important. Others may believe lower weight, sleekness and a quieter ride are more important. That’s cool too. :-)
As you can see, both drivetrains work well. 3/32” will be a little lighter, quieter, more forgiving and sleeker looking. 1/8" will have more chainring and cogs option available. However, there is no strength or durability difference with like chains.
We use 3/32" drivetrains as stock given our philosophy on light weight and a minimalist aesthetic (ie sleeker chain), but we also offer lots of great 1/8" options too.