When it's time to replace your 9-speed cassette, check out SRAM's PG-950 cassette. It delivers solid shifting and durability ride in and ride out for your 9-speed rig.

Shimano's Dura-Ace 10-speed Cassette is comprised of an aluminum cog carrier, 4 titanium and 6 steel cogs (from largest to smallest respectively). This makes for a super-light and stiff cassette that makes your derailleur shift like a dream so you can dance up the climbs as easily and efficiently as your chain climbs up and down these cogs.

Shimano's Ultegra 10-Speed Cassette delivers pro-level shifting and durability. The computer-enhanced tooth shapes and tough cogs mean you can shift quickly, precisely and smoothly even under pressure.

Shimano's 105 10-Speed Cassette delivers excellent shifting and durability. The cogs are made of long-lasing, smooth-running steel. They have Shimano's engineered tooth shapes for precision shifting. And for lightness, the cassette has an aluminum carrier for the top cogs and nylon spacers.

When it's time to replace your old 8-speed cassette, check out SRAM's PG-850. Its steel construction and SRAM's PowerGlide technology combine to deliver miles of solid shifting and outstanding durability.

SRAM's PG-1070 10-Speed Cassette is light, strong and durable. SRAM's PowerGlide technology keeps your gear changes fast and smooth for quiet, reliable shifting mile after mile.

• Chromoly steel • CNC fabrication • 1.29" x 24tpi left hand thread

A range of sturdy, affordable cogs is an essential part of a single speeder's quiver. Origin-8's Torq Lite Single Speed Cog is available in wide range of sizes so you can easily tailor your gearing for the terrain. It's designed for Shimano/SRAM style cassette bodies, features a wide, flex-free base, and is made from hardened chromoly steel.

A range of sturdy, affordable cogs is an essential part of a fixie rider's quiver. Origin-8's Track Cog is available in a variety of sizes and is chrome plated to resist rust and increase longevity. Now you can easily tailor your ride for the terrain. And you can choose between 1/8 and 3/32-inch chain widths.

• Stainless steel with high-polish finish • 1.37" x 24tpi right-hand thread • Requires a lockring (sold separately) • Compatible with 1/8-inch chains

- Chromoly steel with black oxide finish - 1.37" x 24tpi right hand thread - Requires a cog lockring (sold separately) - Compatible with 1/8-inch chains

- Durable cold forged CNC machined freewheel - 3 pawl engagement for stronger hold with engagement every 12 degrees - New removal notch pattern allows for better frame clearance

• Stainless chromoly steel with high-polish finish • CNC fabrication • 1.29" x 24tpi left hand thread

Steel single sprockets with galvanized finish. - Lockring included - Cassette Body Type: Campagnolo 9 Speed - Drivetrain Speeds: 9 - Weight: 212 grams (12-23)

5-speed bronze color freewheel

6-speed freewheel 14-28T SHIMANO Equivalent MF-TZ20

8-speed SIS compatible freewheel

We did our homework on this cog and we think you will be pleased with the result! This 16t cog smooths out the cog to cog transition when using our GC and a standard 10 speed 11-36 cassette. You should expect this to shift well and last as long as the rest of your cassette cogs of similar size. Here are the transitions WITHOUT the 16t cog (4 tooth max jump): - Remove the 15t -> 11-13-17-19.... - Remove the 17t -> 11-13-15-19... Here are the transitions WITH the 16t cog (3 tooth max jump): - Remove 15t & 17t-> 11-13-16-19... Compatibility: Shimano 10 speed cassettes - XT 11-36t (CS-M771) - XTR 11-36t (CS-M980) - Other 11-36t Shimano cassettes like SLX HG81 11-36t - Modification required (must drill out rivets holding the 17t to the larger cogs) SRAM 10 speed cassettes - PG 1030, 1050, and 1070 - 11-36 and 12-36 - X0 11-36t(XG - 1080) - Remove the 14t rather than the 17t

The GC line of cassette extender cogs allow you to modify your 10 speed cassette into a wide range cassette. To achieve the optimal shifting, the GCs are optimized for Shimano or SRAM cassette. Compatibility: - Compatible with SRAM 10 speed cassettes - Compatible with all 10 speed rear derailleurs and chains - Note that you may need a longer chain that you currently have on your bike - Chain stretch should be less than .5 when installing a new GC - Can be run in 2x configuration with a long cage rear derailleur - These fit very tight on certain Stan's No Tubes hubs like the 3.30 and the Easton X4 hubs. With a little filing and some grease they will go on.

Machined from heat-treated, chrome-plated chromoly, these seriously tough cogs will hold up to massive track sprints and crazy skid-stops. Surly's Track Cogs are strong, shiny and they come in two widths and sizes from 13T to 22T so you can select the perfect gear.

SRAM's PG-970 9-Speed Cassette is the perfect replacement for your worn-out gears. It features a rugged steel construction for awesome durability and SRAM's PowerGlide technology for smooth, precise shifts.

Campagnolo's Chorus Cassette offers precise, fluid shifting for your 11-speed drivetrain. The teeth have been exquisitely engineered and machined from steel, then coated with a nickel-chrome surface treatment and mounted on an aluminum carrier for flawless shifts and excellent durability.

Origin-8's Ultim8 Single Speed Cassette Cog lets you have your ride any way you like it. This handy cog is dual use — a single speed cog that fits over a Shimano/SRAM freehub body or a fixed cog that bolts on in place of a 6-bolt brake rotor. A wide, zero-flex base design made of forged chromoly steel provides instant power transfer. Enjoy the Ultim8 ride whichever way you like it.

• 10-speed MTB cassette • Shimano and SRAM compatible • 11,12,13,15,18,21,24,27,30,34 (11-34T) • 11,12,13,15,18,21,24,28,32,36 (11-36T)

A range of sturdy, affordable cogs is an essential part of a single speeder's quiver. Origin-8's Single Speed Cog is available in 13, 14, 16 and 18T sizes is chrome plated to resist rust and increase longevity. It's designed for Shimano/SRAM style cassette bodies and is made with splined, hardened chromoly steel. Now you can easily tailor your gearing for the terrain.

• Steel • 7-speed

• Steel • 8-speed

- 7-speed SIS compatible Freewheel - Shimano Equivalent: MF-TZ21

SRAM's PG-970 DH 9-Speed Cassette is the perfect replacement for the worn-out gears on your downhill or freeride bike. It features a rugged steel construction for awesome durability and SRAM's PowerGlide technology for smooth, precise shifts.

SRAM's WiFLi technology accommodates a wider range of gears than a standard short-cage road derailleur. Compared to a triple chainring setup, it provides faster shifts and significant weight savings. Easy to install on any frame; compatible with all SRAM road 22-speed cranks, cassettes and chains. - For riders who already own Red eTap with a short cage rear derailleur and want to switch to a wide range cassette - Includes Medium Cage Rear Derailleur 11-32 Red 11 Speed Cassette and XG-1190 Red 22 Chain