{"id":9207,"date":"2021-02-22T11:30:25","date_gmt":"2021-02-22T11:30:25","guid":{"rendered":"https:\/\/www.firstcomponents.com\/?p=9207"},"modified":"2021-02-24T08:08:30","modified_gmt":"2021-02-24T08:08:30","slug":"crankset-bearings","status":"publish","type":"post","link":"https:\/\/www.firstcomponents.com\/de\/crankset-bearings\/","title":{"rendered":"Crankset Bearings: From Low to High End (and in between)"},"content":{"rendered":"\n

If you’ve ever asked “What are crankset bearings<\/em>‘? or ‘Are loose bearings better than caged bearings, or even sealed bearings?’, those questions and more are answered right here.<\/p>\n\n\n\n

Crankset bearings vs Cranksets vs Bearings<\/a>
The logic behind the term \u2018crankset bearings\u2019<\/a>
One piece crankset and bearings<\/a>
Sealed crankset bearings<\/a>
Two piece crankset and bearings<\/a>
Three piece crankset and bearings<\/a>
How do you know if your crankset bearings are bad?<\/a>
How long do bicycle crankset bearings last?<\/a><\/p>\n\n\n\n

CRANKSET BEARINGS vs CRANKSETS and<\/em> BEARINGS<\/strong><\/h2>\n\n\n\n

<\/p>\n\n\n\n

Let\u2019s firstly deal with this issue of \u2018crankset bearings\u2019.<\/p>\n\n\n\n

Strictly speaking, the term does not refer to a component in itself.<\/p>\n\n\n\n

The relationship between a crankset and its bearings is mediated<\/em> by the bottom bracket\u2014a bike\u2019s crankset bearings are contained within the bottom bracket.<\/p>\n\n\n\n

Neither bottom bracket or crankset has meaning without the other of course.<\/p>\n\n\n\n

You could even say that the most basic definition of a bottom bracket<\/a> to be: the container for the crankset bearings<\/strong>.<\/p>\n\n\n\n

Crankset bearing setups come in three forms: one piece, two piece, and three piece.<\/p>\n\n\n\n

One piece and three piece cranksets are for low end, cheaper bikes with two piece cranksets dominating the middle and high end.<\/p>\n\n\n\n

Two piece crankset bearing setups, particularly on high-end bikes are predominantly press fit<\/em>.<\/p>\n\n\n\n

Instead of threading into a matching thread in your bike frame\u2019s BB shell, the cups in which bearings are mounted are pressed directly into the BB shell.<\/p>\n\n\n\n

The Logic Behind the Term Crankset Bearings<\/em><\/strong><\/h3>\n\n\n\n

<\/p>\n\n\n\n

The notion of crankset bearings or bearings that enable the crank to rotate arguably stems from the mid 19th century when the first crank-driven bicycles were created.<\/p>\n\n\n\n

\"The
Ordinary replica in Giant Corp’s Taichung HQ museum<\/figcaption><\/figure><\/div>\n\n\n\n

The direct precursor to the modern \u2018safety\u2019 bicycle, the Ordinary or High Wheeler (which you might also know as the Penny Farthing).<\/p>\n\n\n\n

The Ordinary\u2019s crankset bearings setup is unique due to the front wheel direct drive; the 1890s safety bike introduced the modern form of the bicycle: two equally sized wheels, mid-drive crank and pedals connected by a chain to a cog fixed to the rear wheel.<\/p>\n\n\n\n

The cranks<\/a> attach to what is now a wheel hub\u2019s axle, but back then was a spindle rotating inside a cup-and-cone bearing hub shell as the rider pushed the pedals.<\/p>\n\n\n\n

\"Cotter<\/figure><\/div>\n\n\n\n

The \u2018crank bearings\u2019 were simply a grouping of loose ball bearings mounted into the crank, allowing us to view \u2018crank\u2019 as a verb as much as a noun.<\/p>\n\n\n\n

The cotter pin wedge-bolt that holds the cranks on is likely not the original means of holding the cranks to the spindle.<\/p>\n\n\n\n

\"Embedded
Embedded from Flikr. Photo: Ozdavo<\/figcaption><\/figure><\/div>\n\n\n\n

This rare image of an original Penny Farthing crank shows a more complicated setup lacking a cotter pin\u2019s simplicity.<\/p>\n\n\n\n

Still, we can say that the original form of crankset bearings came as a set of bearings closely integrated into the (direct drive) crank. <\/p>\n\n\n\n

ONE PIECE CRANKSET (and Bearings)<\/strong><\/h2>\n\n\n\n

<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

Once piece cranksets<\/a> are not so common these days and are only found on low end entry level mass-market bikes.<\/p>\n\n\n\n

This type of crankset qualifies as possessing its own bearings since the crank spindle and crank arms form a continuous unit on which the bearings rotate.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

It is also the most clear heir to the Ordinary\u2019s original cranks since the bearings are mounted in a cage with the bearings rotating directly around the spindle\/crank, on the inside, and against a cup fitted to the bottom bracket shell on the outward facing edge.<\/p>\n\n\n\n

In other words, there is no bottom bracket unit structuring the bearings in relation to the cranks as with the much more common two piece and three piece cranksets.<\/p>\n\n\n\n

When you install the crank for instance, the bearings install right along with it without fitting a bottom bracket bearing container in advance as with every other type (except BB30).<\/p>\n\n\n\n

Non-Driveside Crankset Bearing Nut and Ring<\/strong><\/h3>\n\n\n\n

<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

The key to this bearing system is the threads cut into a 3-4cm section of the crank on the non-drive side, enabling the lock nut to tighten against the bearing ring and hold the crank\/bearing assembly firm within the bottom bracket shell.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

The nut tightens against the bearing ring preventing it from loosening when a bike is in use.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

The bearing ring constitutes one of this crankset bearing\u2019s three elements:
1 Bearing ring
2 Ball bearings (loose or in a cage)
3 (Inner) Bearing Cup<\/p>\n\n\n\n

A tighter bearing ring is better although if it\u2019s too tight, there\u2019ll be too much pressure on the bearings which will constrict crank rotation.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

These bearings rotate in a cage with the outer surface of each bearing making contact with a cup pressed into the bottom bracket shell.<\/p>\n\n\n\n

Unscrewing the bearing ring releases direct pressure on the cage which also loosens the crankset bearing structure as a whole.<\/p>\n\n\n\n

Sealed Crankset Bearings<\/strong><\/h3>\n\n\n\n

<\/p>\n\n\n\n

Before the advent of caged bearings, ball bearings ran loose inside the bearing ring, or cone, and the cup.<\/p>\n\n\n\n

Apart from classical bikes still in good working condition, or their classical replicas, all crankset ball bearings in modern bikes are contained inside cages.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

The most common form for bike bearings, including crankset bearings, is the sealed bearing<\/em>.<\/p>\n\n\n\n

Ball bearings are contained in a cage. The cage, in turn, is loged within an alloy shell.<\/p>\n\n\n\n

One side is open, allowing access to the bearings in their cage. That side is covered by a rubber seal which can be lifted away so that the bearings can be cleaned, flushed, and then re-greased, although it\u2019s more convenient to replace an older sealed bearing with a new unit.<\/p>\n\n\n\n

Sealed bearings retain grease for their working life and the seal effectively keeps out most grit.<\/p>\n\n\n\n

But given the crucial part they play in crankset function, they are relatively cheap to swap out should bearing performance be inhibited by gravel or mud particles.<\/p>\n\n\n\n

TWO PIECE CRANKSET (and Bearings)<\/strong><\/h2>\n\n\n\n

<\/p>\n\n\n\n

Going from one to two pieces is a logical, but not historical, progression, since three-piece cranksets consisting of ball bearings, a spindle and two cranks pre-date them all as we saw when discussing the 19th century Ordinary.<\/p>\n\n\n\n

\"Integrated
Integrated crank spider without chainrings<\/figcaption><\/figure><\/div>\n\n\n\n

A two piece crankset is better known as an integrated crank<\/em> : a hollow spindle is fused to the drive side crank with the non-drive side crank bolting to the end of the spindle where it emerges from the bottom bracket on that side.<\/p>\n\n\n\n

The image above displays the disassembled form of this crank, prior to the chainrings being bolted to the crank spider.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

The crankset bearings in a two piece crankset are contained in an external or outboard bottom bracket.<\/p>\n\n\n\n

In contrast to one piece and three piece cranksets, two piece crankset bearings have been relocated from inside the BB shell to the outside, reducing weight and increasing crankset bearing longevity since larger diameter ball bearings can be used.<\/p>\n\n\n\n

Press Fit Crankset Bearings<\/strong><\/h3>\n\n\n\n

<\/p>\n\n\n\n

The most revolutionary change (not \u2018advance\u2019 by the way\u2026more on that later) in the last two decades has been the advent of press fit bearings.<\/p>\n\n\n\n

\"Embedded
Embedded from bicyclepartsdirect.com<\/figcaption><\/figure><\/div>\n\n\n\n

The press fit \u201crevolution\u201d began with a design move that looked back to the original form of crankset bearings: placing bearings directly into the frame in the way that the Ordinary\u2019s direct drive front wheel crank bearings were located in the wheel hub.<\/p>\n\n\n\n

Instead of loose bearings, though, a sealed bearing is braced against a C-clip that squares against a ridge machined into the BB shell.<\/p>\n\n\n\n

This design\u2019s rationale was to enlarge the BB shell from the standard 34.8 mm to 42 mm, thus enabling a crank with a larger diameter spindle to be fitted, which would be stiffer and lighter.<\/p>\n\n\n\n

The problem was the whole assemblage\u2019s tendency to move slightly in the BB shell, particularly the sealed bearing<\/p>\n\n\n\n

This setup soon gained a reputation for creaking which quickly led to the development of the PF30 press fit standard: crankset bearings were relocated into cups which were then installed, which also had their share of problems.<\/p>\n\n\n\n

Thus we are now in the midst of a move away from press fit and back to threaded bottom brackets in the form of the new T47 standard.<\/p>\n\n\n\n

I\u2019ll finish off this section with a word on the three most common forms of two piece cranksets around today: standard, compact, and single (1x) chainring.<\/p>\n\n\n\n

Standard Crankset<\/strong><\/h3>\n\n\n\n

<\/p>\n\n\n\n

\"Standard
Compact (in relation to standard)<\/figcaption><\/figure><\/div>\n\n\n\n

A standard crankset is so named due to the relative sizes of the big and small chainrings.<\/p>\n\n\n\n

Juxtaposing standard and compact immediately reveals the contrast between these designs.<\/p>\n\n\n\n

Convention has arrived at a 53 T (\u2019T\u2019ooth) big ring and a 39T small ring.<\/p>\n\n\n\n

These sizes are fine for reasonably strong and fit road cyclists, particularly with the move towards larger cogs in the order of 28T to 34T or larger.<\/p>\n\n\n\n

But if you are an average rider cycling the hills more than the flat, then a compact crank is highly recommended.<\/p>\n\n\n\n

Compact Crankset<\/strong><\/h3>\n\n\n\n

<\/p>\n\n\n\n

For cyclists riding hilly areas, a big ring of 50T and a small ring of 36T or even 34T makes ascending hills much easier.<\/p>\n\n\n\n

1x Crank<\/strong><\/h3>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n

The 1x revolution in a nutshell:<\/p>\n\n\n\n