Bicycle Drivetrain Guide
Product Information
Bicycle Drivetrain Guide
Your bicycle’s drivetrain is comprised of all of the parts that power the bicycle and make it go. Bike pedals move the cranks, which turn the bottom bracket and the chainrings, which drive the chain that spins the rear sprockets, turning the rear hub, which moves the wheel and propels the bicycle forward. The crisp movement of these parts and the ability to minimize effort while maximizing speed is the heart of cycling. It is essential that drivetrain be clean, true and well-maintained in order to more fully enjoy riding your bike. When one of these parts gets out of whack, the rest soon follow.
It is also important to get individual components that are compatible within the system (e.g. typically Campagnolo and Shimano parts are not inter-compatible). Many times the difference between 9- and 10-speed parts is enough to make them incompatible as well. The collective term for a complete bike drivetrain kit is “group” or “gruppo.” Multi-speed drivetrains are classified by the number of cogs in the rear cassette. A modern day 10-speed bicycle can have as many as 30 “possible gears,” with 10 in the rear and three in the front, but still have a 10-speed drivetrain.
Pedals
Your bike pedals are your power connection to your bicycle. As you pump your legs and turn your feet, you cause the cranks to turn. Proper pedal choice is important for comfort, control and safety on the bike. Many recreational and enthusiast cyclists prefer the adaptability that platform pedals offer. They allow you to ride in any type of shoe and give a sense of security to a novice rider who is cautious of locking the feet into clipless pedals. Many platform pedals can be adapted with a toe cage to give more control and power while retaining the sense of security associated with platforms.
Racers and more advanced riders often prefer “clipless” pedals. These pedals are used in conjunction with matching cleats that are attached to special shoes. The cleats lock into place in the pedal, offering a secure attachment of rider to bicycle. Most cleats easily release the shoe by a simple twist of the ankle, and they are quite easy to use with some initial practice.
Cranks
The cranks connect the pedals to the bottom bracket and hold the front chainrings. They connect to the axis around which your feet spin and transmit your power to the bike. Cranksets come in many different lengths based upon bicycle frame size and the rider’s leg length. They are generally made out of aluminum, but some low-end cranks are made of steel, and some high-end cranks are made of carbon fiber. These cranksets are marketed to top-level racers and generally carry the appropriate price tag. Cranks attach to the bicycle at the bottom bracket. There are several types of cranks/bottom bracket interfaces, and it is important to know their differences.
Chainrings
Chainrings are the forward chain interface with the bicycle. They contain teeth that hold the chain and drive it forward. Chainrings come in a wide range of sizes, identified by the number of teeth and application. Typical mountain bikes use three chainrings; road bikes generally have two to three. Single-speed and fixed-gear bicycles use only one chainring. Chainrings are typically made of aluminum, with some being made of steel and a handful of boutique brands making them out of carbon fiber.
What makes a proper chainring is dependent upon many factors: number of teeth, single/double/triple configuration, 8/9/10/11 speed use and bolt circle diameter. Once all of those factors have been determined, you can choose the group level or brand that best suits your needs.
Bottom bracket
The bottom bracket is the cranks’ interface with the bike. It contains bearings around which an axle rotates; this axle is connected to the cranks. Current bottom brackets come in varying interface types. Traditional bottom brackets have loose ball bearings with their accompanying cups and cones and an axle locked in place with locknuts, typically on the left side of the BB shell. More recent cartridge bottom brackets are built as one piece with cartridge bearings press-fit onto the axle and fit into the frame with “cups” that thread into opposite sides of the shell.
Many bike parts companies have most recently been developing bottom brackets without an axle. The axle is built into the cranks and runs through bearings that are press-fit into cups that thread into the bottom bracket shell. The other end of the axle then attaches to the opposite crankarm. Different brands have different bearing sizes and only work with their respective cranks.
Bottom brackets come in many different interfaces developed by the different component manufacturers. Cup and cone BBs are generally “square taper.” Cartridge bottom brackets are one of two versions of square taper (International Standard or Japanese Standard) or one of the many versions of splined BB developed by the several companies.
Another important aspect of bottom bracket compatibility is whether your bicycle has an Italian or English threaded bottom bracket. The shell diameter of an Italian bottom bracket is larger, threaded 36 mm x 24 tpi, and its threads are both normal (or right-handed). English bottom brackets are threaded 1.370-inch x 24tpi, with the right cup having a reverse thread and the left cup having a regular thread.
Chain
The chain connects the chainring to the rear sprocket, transmitting power from the rider to the rear wheel. Current bicycles use roller chains (with few exceptions) that are categorized by pitch and width. The chain’s pitch is the distance from roller to roller and is typically 1/2 inch on modern bicycles. The width is measured between chain plates and is either 1/8 inch for derailleur-less bikes and 3/32 inch for multi-speed, derailed bikes.
Another specification of a bicycle chain is based on outer width: the outside distance between chain-link plates. There are two main standards: Campagnolo and Shimano. Shimano uses the same width chain for all drive trains with eight or fewer gears in the rear cassette or freewheel and a different width each for its 9- and 10-speed groups. Campagnolo uses three widths presently: 9, 10 and 11. As the number of sprockets in the rear increase, the width of the chain must decrease, providing enough clearance for the extra gears. Other companies manufacture chains that are designed to work with the Campy and Shimano systems.
Derailleurs
On multi-speed bicycles, the derailleur moves the chain from one sprocket to another. They are actuated by a cable pulled from the shifters, typically mounted onto the handlebars (and sometimes down tubes) of the bicycle.
Front derailleur
The front derailleur moves the chain from chainring to chainring and acts as a chain guide, keeping the chain aligned. There are several chainring characteristics to consider when shopping for a front derailleur. The most important is double or triple (whether there are two or three chainrings attached to the crank). A triple front derailleur is designed with a deeper inner cage than a double derailleur to be able to push the chain up from the small ring.
Another key characteristic is chainring size. Certain derailleurs’ cage diameters limit the maximum number of teeth possible on the large ring. The final characteristic is 8/9/10-speed compatibility. The width between the inner and outer cage varies between designs and may not work well when used with the wrong gearing.
Rear derailleur The rear derailleur acts as a chain guide and chain tensioner. As the chain moves from a large sprocket to a smaller one, it needs less chain to cover the circumference. The rear derailleur has a spring mechanism that pulls in that extra length of chain, known as “chain wrap.” The rear derailleur also moves the chain from cog to cog and is one of the more active components of the bicycle. As you pedal and drive the chain around the chainrings and rear sprockets, the chain continuously runs through the rear derailleur.
Rear derailleurs are classified in the same manner as front derailleurs–first by speed: 8/9/10, then by double or triple (it is actually the difference between the largest and smallest chainring added to the difference between your largest and smallest cog). Typically, with a double chainring you can use a short cage and with a triple you would need a long cage. The longer cage helps take up the extra slack that appears when in the small ring.
Rear sprocket
The rear sprocket is the chain’s rear interface with the bicycle. On a single speed (fixed gear included) you only use one rear sprocket, or cog. Multi-speed bikes have a cluster of cogs called “cassettes” or “freewheels.”
A freewheel is a group of cogs fixed to a “freewheel” mechanism that allows you to coast; there is a ratcheting mechanism that allows the rear hub to spin as you coast, or ride without pedaling. A bike cassette is designed to be used with a rear hub equipped with a freewheel mechanism to which you attach the cogs.
Typical freewheels come in 5- to 7-speed versions, and cassettes are 8/9/10/11-speed, with few exceptions. Cassette cogs are designed to be set up in a particular orientation to aid in shifting; any variation of this orientation can cause serious shifting and safety issues. Cassettes are designed to be used with the appropriate chain, and the wrong chain won’t ride on the teeth properly, resulting in a very poor and annoying ride.
Rear hub
The rear sprocket is attached to the hub directly (in the case of a fixed gear), or via a freewheel mechanism. The power from the front chainring is transmitted via the chain to the rear sprocket and into the rear hub, the central point of the rear wheel. The two main characteristics of a rear hub are hub type (cassette, freewheel or fixed) and hub spacing (the width from axle end to axle end). Modern road bikes are spaced to 130mm, mountain bikes to 135mm and track bikes to 120mm. Older bicycles were spaced to 126mm. They were typically designed for use with freewheel-type rear hubs that carried fewer gears.
With the advent of the freewheel hub and more gears, the rear dropout spacing was increased to accommodate. Another thing to consider when choosing a hub (if it is already built as part of a wheel) is the wheel diameter. The rim must be the appropriate size to fit into the frame and line up with the brake pads.
I suggest Bike Wagon for bike parts.
Jon Carter is an avid cyclist and loves to write on the subject. Make sure to go check out Bike Wagon for all your biking needs.
Shimano SPD-SL Road Pedals, Black
- Shimano PD-R540 SPD-SL Road Pedals, Black
Single-sided binding engagement with adjustable cleat tension (105 level). Low profile, sole axle distance: 14.5mm. Larger cleat/pedal interface for better stability. Nylon resin cleats with non-slip rubber base (6-degree stock). SPD-SL 3-bolt (Look style), SM-SH10/11 0(red)/6(yellow) degree cleats. Wide bearing placement with 3 sets of sealed bearings (2 ball-type and 1 needle-type).
Rating: 
(out of 18 reviews)
List Price: $ 69.99
Price: $ 47.99
Shimano SPD PD-M520 Mountain Bike Clipless Pedals 9/16"
 | US $15.36 (9 Bids) End Date: Sunday May-20-2012 12:46:28 PDT Bid now | Add to watch list |
 | US $12.00 (1 Bid) End Date: Sunday May-20-2012 14:09:37 PDT Bid now | Add to watch list |
me unbxoing my azonic o’neal fury helmet in white, my answer impact ’07 shoes, and shimano spd clipless pedals, there all really awsome!
Video Rating: 2 / 5
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dude control your breathing….its like your have an orgasm attack or something……its just a helmet!
only achieving to make an endorsement for Jensonusa.
just an endorsement video about Jensonusa
@socomkid88 hmmm…
@xMTBxBOYx27x oh and btw i just got home from newhampshire have about 2 hours of downhill footage once i get it up then you can say i dont dh or im not that good, i rode expert trails the first day and at the end of the trip i was going damn fast and damn good, my uncle was afraid how fast i was going for the first time downhilling………
jesus you have a fucking orgasim over a helmet
@xMTBxBOYx27x ok dude w/e think what you want… i do bigger stuff in then in my vids.. its just my mom refuses to even watch me wether lone record me do anything, she is so afraid i will fall… but trust me dude i do bigger stuff, and im going up to newhampshire and there will actually be good stuff to ride and dh trails… ill try to get a video but ill be with my uncle and dont know if he will want to wait to take some video..
why do you bother getting a helmet like that,, you most likely do not do any hardcore downhill or any kind of free-rideing,,,, ur a wanna be biker
1:58 haha!
what are you jizzing over your moutain bik helmet jezze calm down man
@dijon458 did you get it?
mines comin today
@dijon458 yeah its a good helmet and i am doing bigger stuff but the landing ramps were wet and i road up them to see if they were ok and my tire like sunk in to it a little bit, so i decided not to hit, and plus the camera died so i couldnt get it on video if i did do it anyway…. but yeah its good helmet..
is it a good helmet? i just orderd it in black. and not to be mean, go for some 7 foot drops. same as a 1 footer but bigger and harder
i got an 08 stinky with mavic deemax and drop off III. got some big drops in my backyard
@venskus2009 i was 12 in this video now im 13
Youre like 10 wtf
@dijon458 only a couple days , cant really remember but i know it wasnt even a full business week
how long did it take to come?
i orderd the same. how long did it take to come?
@SyedTheDulax oh ok
@frankster262 put down..or high place…
@SyedTheDulax put my camera what?
it really nice to see the item but…after this! please…put your camera!
@perlagee wow.. i really dont give a flying fuck, even if i had all of them in the world
fat ass
Review by Thomas Lyon for Shimano SPD-SL Road Pedals, Black
Rating:
For the money, I don’t think you can do better. Easy in, easy out, really no trouble and just enough float. I like these and the look style is the easiest to learn for those new to clipless. Don’t be scared. If you’re ready for the switch to clipless this is a good pedal. You won’t believe the difference in speed and power from your clips.
Review by Gabriel Espinola for Shimano SPD-SL Road Pedals, Black
Rating:
If you are not a weight freak and you need a reliable set of road pedals these babies are awesome, I have a decent road bike and I wanted to upgrade my old set of mtb pedal/shoes that I used for a couple of years, I have been cycling more and more and I thought this was a necessary upgrade and honestly I don’t see why should I buy a more expensive set, I just don’t see the point, at least until I get a pro bike. My family has a cycling related business and you should know that Shimano is one of the best cycling parts producer so you are going with a good brand, a very good looking, reliable and lightweight piece of engineering. This set comes with a set of cleats 3-bolt LOOK-Style compatible so look for the right shoes before getting the pedals, 3-bolt LOOK-Style is the most common kind of road shoes though.
Also before you adventure in the awesome world of clipless pedals be sure you create the reflex of taking them out, you can start with a loosen setting and keep tighten it up until you have enough practice and feel comfortable with them, please don’t be a risk for other riders/pedestrians/cars.
Hope it helps and happy riding!
Review by C. Rollins for Shimano SPD-SL Road Pedals, Black
Rating:
I had been off of the bike for almost this entire millenia. 20 years ago, when I was riding fairly seriously, I always thought about upgrading to some clipless pedals, but I just never did. Upon a recommendation from my local bike shop, I placed these on my 1986 Raleigh Grand Prix, added some new Specialized Sport Road shoes, and away I am going. The pedals hold my feet in very nicely, allowing a little bit of play as I’d like, and I did not have to mess with the tension adjustment – I was able to unclip with the normal rotation of the foot. Why anyone would pay so much more for other types of pedals is beyond me. Yes, they are pretty large, so they may add an extra microgram to your total weight, but seriously folks, us common riders can’t possibly tell!
Review by Matthew for Shimano SPD-SL Road Pedals, Black
Rating:
I’ll start off by stating that I am new to clipless pedals. I put these on my new road bike and have to say I am very impressed. When I got the bike I must have clipped in and out 100 times before I even ventured out with them and the payoff has been well worth it. Clipping in and out is a cinch. I like the SPD pedal as it had a relatively large area to clip in. Another interesting finding that these pedals weigh in at 330 grams. The Shimano Dura Ace SPD pedals that run near $300 weigh 278 grams. That is a 52 gram difference for almost $250 more money. That is 1.84 OUNCES. I am riding a $1700 bike not a $6000 bike so I can deal with an extra 1.84 ounces weight on my bike. I know it is not only about the weight but you get my point. That is why I think these pedals are the best bang for the buck as they are relatively inexpensive for what you get.
Review by J. Dadd for Shimano SPD-SL Road Pedals, Black
Rating:
Good pedals for the money. My first road-specific ones (SPD prior to these). They seem light enough, but then I’m not a weight freak and cannot justify $200 to shave off grams! Very easy to fit onto bike, and setup of the cleats on my shoes did not cause a problem. I tried to loosen the release pressure and found I had a slightly tight allen-screw on one pedal, but not a problem with the right allen-key size. All in all, very pleased with this purchase.
(The pedals came from Niagara Cycle Works, and very pleased with the speed of delivery).