welcome back to Berm Peak i'm Seth and today we're going to be doing something a little different
but kind of the same we're going to be talking about the benefits of the three-by drivetrain
now to those of you who watch the channel a lot that's going to seem weird because oftentimes i'm
ripping these off of bikes because they're heavy and difficult to use and difficult to maintain
and noisy and in a crash they become ninja stars but we're gonna forget about all that stuff today
because actually I don't hate three buys they have their place on certain bicycles oftentimes
they're more economical and there are certain advantages that the one buy just cannot provide
now for those of you who don't really know what i'm talking about let's clear it up real quick
this is a derailleur and this is a cassette this cassette has seven gears on it as you shift
through those gears the bike either becomes easier to pedal uphill or faster with each pedal stroke
this bike actually has a front derailleur and three chain rings between those three chain rings
and this seven speed rear cassette the bike has 21 possible gears it's a 3x7 a 21 speed bike
now each of the cogs on this seven speed cassette have teeth
on the smaller end we have 12 teeth and on the larger end we have 28 teeth
this is a modern mountain bike cassette and it has 12 gears on the smallest end it's 10 teeth and on
the largest it's 50. this cassette has so much range that we only need one gear up front this
is a one-by 12. so for the range of gears that we use in mountain biking the one-by drivetrain
has become all but ubiquitous it's simpler it's lighter it's more user friendly it doesn't become
a ninja star in a crash and it tends to run a lot quieter but there are still mountain bikes
that come with three-by drivetrains and if you have one you actually have some advantages over
people with a one-by and in the interest of fairness we're going to discuss those today
let's start with longevity if you have a one-by drivetrain that ring up front is
always making contact with the chain on a three-by you have three rings sharing the load of the chain
and so technically speaking they last longer but it doesn't end there often times on a three-by you
have a smaller cassette with bigger gaps between the gears and oftentimes those gears are bigger
and thicker so there are certain situations where the cassette lasts longer and the chain
definitely lasts longer because it's a wider heavier chain if you have a friend who races
enduro or xc often times you'll see them wearing through drivetrain parts in one year even a season
whereas you'll find an old bike with a three-by and all the original parts it was born with
are still on the bike let's also talk about cost there's a reason why inexpensive bikes oftentimes
come with a three-by drivetrain they've been making them for years and they can just poop
them out of a machine for next to nothing these same drivetrains have been made for decades
and so through economies of scale companies can get them for a few bucks a piece also the wider
cassettes on one-by drivetrains take more advanced tooling to produce the gears are narrower and
closer together and any error in the manufacturing process is going to have a bigger effect on how it
works so it actually is more expensive to make you also need a narrower chain on a one-by drivetrain
and so it needs to be made from stronger material in order to have a thin light chain that's
gonna be able to deal with those stresses it's actually more expensive to make where let's say a
three-by eight or a three-by nine can just have a big heavy chain that stands up to whatever abuse
you throw at it so for the range you get there is a cost advantage to a three-by drivetrain
another arguable sometimes advantage of a three-by drivetrain is chain retention
I spoke to an engineer from a bike company that was explaining to me why they put these
on inexpensive bikes and I was surprised to find out it's for chain retention when you're
dealing with an inexpensive drivetrain where the chain is flopping everywhere
there is an advantage to have the chain going through a derailleur in the front
because that chain is now unable to pop completely off the bike and so for a beginner that doesn't
necessarily know how to maintain their drivetrain this ensures that the chain stays at least sort of
on the bike at all times so for companies trying to make an inexpensive bike as safely as possible
the front derailleur has a dual purpose range and chain retention
the next advantage to a three-by drivetrain is my personal favorite and what I think is objectively
the biggest thing you're losing by going one-by and that is the ability to drop to a lower gear
by going to a smaller cog let me explain why this is important i've mentioned in
past videos the terrible sounds your bike makes when you try to shift gears under load
this happens most often when you encounter a punchy climb and you have to downshift in a
hurry on a one-by mountain bike your only option is to shift to a bigger chainring in the back
to do this you have to be pedaling and the chain has to climb to a bigger gear
the springs in your derailleur cage take up the load as your chain climbs up the cassette if
you do this with pressure on the pedals it makes horrible noises and happens often when you have to
change gears in an emergency that doesn't happen on a three-by on a three-by drivetrain you can
drop the chain to a smaller gear at the click of a button you are in a dramatically lower gear that
you can climb hills with there's no clanging or grinding or anything it just shifts gears reliably
even if the drivetrain is under load now of course you already have to be in the largest
or middle gear in order for this to work but oftentimes if you were pedaling fast you are
and when one-by drivetrains first became popular the curmudgeons in the comments section were
having a ball over this and there's really nothing you can say because they're right so
riding a one-by drivetrain forces you to change your habits a little bit because a
lot of people were relying on the fact that they could drop into a low gear in one click of a
button on their three-by and a lot of people don't want to let go of it because of that
when any drivetrain is operating you have your drive gear up front and then you have
your gear in the back ideally these gears are completely in line with each other so that
the chain has an easier time making its way onto the gear but on any system with a derailleur your
chain line is not always going to be straight but this is more so on the more modern one-by
systems because you only have one gear up front the chain has to move its way across the cassette
and be kind of torqued in one direction on a three-by you can get your chain line straighter
now having a straighter chain line has a few advantages it does oftentimes feel smoother it
technically puts less wear on the chain and the teeth and in certain situations if you
use a three-by properly it is a reason why it may last longer now the fact that chain lines
aren't always going to be straight has been engineered into modern one-by systems but it's
still an objective reality that you can have a straighter chain line on the older three-by system
so I have no proof of this but I suspect that some people use the three buy as a marketing tool if
you're marketing a bike to a less experienced buyer well more gears must be better to explain
to somebody why less gears might be better takes a little bit of explaining you have to explain to
them about the reduction in clutter the ease of use but to explain why 29 gears are better
or 24 gears or better well that's simple more is better now let's forget about the fact that a lot
of these gears are practically unusable because of cross chaining or that you're adding about a pound
of weight to the bike that doesn't matter when you're trying to get the most features you can
for the smallest amount of money and so especially in department stores you will see
marketing points on bikes and big letters 21 gears 24 gears they're trying to sell you on the fact
that the bike has more gears when more gears is not necessarily what you want it's usable gears
it's not necessarily a bad thing since these bikes would probably have those drivetrains in
the first place it just seems to be an unusual marketing point that might actually work
the final advantage to a three-by drivetrain mainly applies to people who hate on anything new
back in the early 90s when suspension forks became popular there were people who hated on them and
said they would never catch on same thing happened with dropper posts and indeed it did happen
when one-by drivetrain started to become more ubiquitous you're paying more for less gears chain
line where it is true that with the advantages I gave you today you can be a more effective
curmudgeon as your riding buddies are crunching their drivetrains before that punchy climb
you can scoot right past them drop a ring and tell them they're stupid for having a one-by drivetrain
when i'm trying to ride as effectively as possible I will definitely rely on my one-by it's just
better in so many different ways it's quieter it's easier to use it's endless but sometimes I can
be a bit of a curmudgeon myself I like three-by drivetrains the same way that people like stick
shifts in cars they're slower than new electronic transmissions but they're fun when i'm riding my
vintage bike around that three-by drivetrain is a novelty and I find it fun I use all the benefits
of it and enjoy them and embrace them I try to get my chain line as straight as possible I use that
dropping into a smaller ring trick when a punchy climb comes up and just like a stick shift on a
manual transmission car it makes me a little bit nostalgic for when bikes were different
so if you still have a three-by drivetrain on your bike remember that all the advantages I
listed today still hold true thanks for riding with me today and I'll see you next time