Best Single-Speed Bike Conversion Kits
The CyclingDeal FK-02 is the best simple cassette-hub conversion kit. Compare it with the FK-03 tensioner bundle and check compatibility before buying.
Table of Contents
The CyclingDeal FK-02 is the best single-speed conversion kit for a bike that already has usable chain tension, such as a frame with horizontal or sliding dropouts. Choose the CyclingDeal FK-03 bundle when a conventional vertical-dropout frame also needs a derailleur-hanger tensioner.
Both kits convert a compatible Shimano- or SRAM-pattern cassette freehub to a coasting single speed. Neither converts the hub to fixed gear. A fixed-gear conversion needs a hub designed for a fixed sprocket and reverse-thread lockring; read our fixed-gear conversion guide before assuming these kits can do both jobs.
Choose the chainring and cog combination with our single-speed gear ratio guide before ordering a conversion cog.
Size the replacement chain only after the cog, chainring, chainline, and frame-tensioning method are established.
The best single-speed conversion kits at a glance
| Pick | Includes | Best for | Important limit |
|---|---|---|---|
| CyclingDeal FK-02 | Cog, cassette spacers, lockring | Frames that can tension the chain without a derailleur-hanger tensioner | Does not include a tensioner |
| CyclingDeal FK-03 | 16-tooth cog, spacers, lockring, hanger-mounted tensioner | Vertical-dropout frames with a compatible derailleur hanger | Tensioner is for 3/32-inch chains, not 1/8-inch chains |
Before you buy: check the hub and frame
Remove neither the cassette nor the derailleur until you know what is installed. These kits fit a splined cassette freehub. They do not replace a threaded freewheel, an XD/XDR driver, a Micro Spline driver, an internally geared hub, or a fixed-gear hub.
Next, identify how your frame sets chain tension:
- Horizontal, track-style, or sliding dropouts can move the rear wheel to tension the chain.
- An eccentric bottom bracket can adjust chain tension without a separate tensioner.
- Conventional vertical dropouts normally need a tensioner mounted to the derailleur hanger.
- A frame without a derailleur hanger cannot use the FK-03 tensioner as designed.
Check chainline after installation. The front chainring and rear cog should run in the same plane. The included spacer assortment lets you move the cog laterally on the freehub, but it cannot correct every crank or chainring position.
1. Best simple kit: CyclingDeal FK-02
CyclingDeal’s manufacturer listing for the FK-02 specifies compatibility with Shimano- and SRAM-pattern 7- through 11-speed cassette bodies. It includes two 10 mm spacers, one 5 mm spacer, four 3 mm spacers, an alloy lockring, and a chromoly-steel cog.
The product name uses “fixie,” but the manufacturer explicitly says the kit leaves the hub as a freewheel. That means you can coast. It is a single-speed cassette conversion, not a fixed-gear conversion.
This is the better kit when your bike already has a sound way to set chain tension. It costs less, has fewer moving parts, and leaves tensioner choice open if your frame needs a different solution.
Best simple kit
CyclingDeal FK-02 Single-Speed Conversion Kit
4.2 out of 5 (1,228 ratings, as of July 26, 2026)
The cleanest choice when your frame has horizontal or sliding dropouts.
A cog-and-spacer kit that converts a compatible multi-speed cassette freehub to a coasting single speed.
Best for: Compatible cassette freehubs on frames that can already tension the chain
Key specifications: 16-tooth cog; seven spacers; lockring; 7- to 11-speed Shimano/SRAM-pattern cassette-body compatibility
Trade-off: No chain tensioner is included.
- Chromoly-steel rear cog
- Two 10 mm, one 5 mm, and four 3 mm spacers
- Compatible with common 7- through 11-speed chains
Pros
- Large spacer assortment helps establish a straight chainline
- Keeps the setup simple when a separate tensioner is unnecessary
- Two-year manufacturer warranty
Cons
- Does not tension the chain
- Does not fit every freehub standard
Considerations
Verify that your wheel uses a compatible splined cassette body. This kit does not make a fixed-gear hub.
2. Best kit with a tensioner: CyclingDeal FK-03
The FK-03 combines a 16-tooth version of the spacer kit with an aluminum tensioner that mounts to a derailleur hanger. The manufacturer’s FK-03 specifications list an 11-tooth plastic pulley and adjustment hardware.
This is the practical package for many geared mountain-bike and hybrid frames with vertical dropouts. The tensioner takes up chain slack that the axle position cannot remove.
Compatibility is narrower than the product title suggests. The manufacturer says the tensioner fits 3/32-inch chains and not 1/8-inch chains. It also recommends a round or oval chainring to reduce chain-drop risk. A damaged or nonreplaceable derailleur hanger can rule it out.
Best with a tensioner
CyclingDeal FK-03 Conversion Kit and Chain Tensioner
4.2 out of 5 (164 ratings, as of July 26, 2026)
The more complete option for converting a conventional geared frame.
A cassette-body conversion kit bundled with a derailleur-hanger chain tensioner.
Best for: Vertical-dropout frames with a compatible derailleur hanger
Key specifications: 16-tooth cog; spacer set; lockring; hanger-mounted aluminum tensioner; 3/32-inch chain compatibility
Trade-off: The tensioner adds another moving part and does not fit 1/8-inch chains.
- 16-tooth chromoly-steel cog
- Cassette spacers and alloy lockring
- Aluminum tensioner with an 11-tooth pulley
Pros
- Solves chain slack on many vertical-dropout frames
- Includes the cog and spacer hardware in one package
- Adjustable pulley position
Cons
- Not compatible with 1/8-inch chains
- Requires a suitable derailleur hanger
Considerations
Check freehub, hanger, chain-width, and chainring compatibility before dismantling the original drivetrain.
How we chose
We started with products from the legacy article, then checked exact Amazon ASIN records through Bright Data on July 26, 2026. Products that were unavailable did not remain recommendations. Ratings above are retailer signals, not our test scores.
We verified consequential compatibility details against CyclingDeal’s own product pages. We favored complete specifications, multiple spacer widths, replaceable standard parts, and a clear distinction between coasting single speed and fixed gear. We did not conduct a new hands-on test.
What tools will you need?
Most cassette conversions require:
- The cassette lockring tool that matches the existing cassette
- A chain whip to hold the cassette during removal
- An adjustable wrench or socket for the lockring tool
- A chain tool and, when applicable, a compatible connecting link
- Hex keys for the derailleur, chainring, and tensioner hardware
- A ruler or straightedge for the initial chainline check
- A torque wrench and the component manufacturers’ torque specifications
Our bike tool-kit guide explains which tools are worth owning. Stop if you cannot identify the freehub, if the lockring tool does not seat fully, or if the derailleur hanger appears bent or damaged.
Choosing a gear ratio
A 2:1 ratio, such as a 32-tooth chainring with a 16-tooth rear cog, is a common starting point for mixed off-road use. It is not a universal best ratio. Terrain, wheel size, tire size, fitness, and loaded bike weight all change how it feels.
Use a larger rear cog or smaller chainring for easier climbing. Use a smaller rear cog or larger chainring for more speed at the same cadence. If your route has sustained steep climbs, preserve the geared drivetrain until you know a single ratio is practical.
Installation checks that matter
After setting the spacers and chain length:
- Rotate the cranks by hand through several full chain revolutions.
- Watch the chain as it enters and leaves both sprockets.
- Confirm that the chain does not tighten dramatically at one point in the rotation.
- Verify that the rear cog and front chainring form a straight chainline.
- Secure every fastener to the relevant manufacturer’s specification.
- Test the brakes before a low-speed ride in a traffic-free area.
A tensioner should take up slack without forcing the chain sideways. Do not ride if the chain derails, binds, or runs close to the spokes.
If the crank or bottom bracket has play, diagnose that separately with our crank-bearing guide before attempting the conversion.
Frequently asked questions
Can any bike be converted to single speed?
No. The hub standard, dropout design, derailleur-hanger arrangement, chainline, and available gear ratio all matter. Some full-suspension frames also change chain length as the suspension moves, which can make a simple conversion unsuitable.
Does a conversion kit make a fixie?
No. The two kits here retain a freewheel mechanism, so the bike coasts. A safe fixed-gear setup needs a proper fixed hub or fixed side of a flip-flop hub, a fixed sprocket, and a reverse-thread lockring.
Can I reuse the original chain?
Sometimes. The FK-02 supports several common derailleur-chain widths, but chain wear and the selected cog still matter. A worn chain may skip on a new cog. The FK-03 tensioner is limited to 3/32-inch chains.
Do I still need brakes?
Yes. A coasting single speed needs functioning brakes. Even a fixed-gear bicycle should retain legally required brakes and a reliable independent way to stop.
Bottom line
Choose the CyclingDeal FK-02 when your frame can set chain tension on its own. Choose the FK-03 when a compatible vertical-dropout frame needs a hanger-mounted tensioner. If you cannot confirm the freehub standard, dropout type, and chainline, have a bike shop identify them before ordering.
