Bike models › Kids
REI Co-op Cycles REV 24: specs, upgrades and what fits
A 24-inch kids' trail bike with a rigid aluminum frame and fork, 2.6 in. plus tires, a Shimano Tourney 7-speed twist shifter (14-34T) and Tektro mechanical disc brakes. Best for: Kids about 8 to 12 riding dirt paths and easy trails.
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My take, from the specs
A 24-inch trail bike for kids about 8 to 12, with 2.6-inch plus tires for grip, a 7-speed twist shifter and Tektro mechanical disc brakes. At about 12.8 kg it is heavy for smaller riders, and the rigid fork relies on the big tires for comfort. REI does not publish the top seat height, so taller kids should check the fit.
Sizes: 24in: 4′2″–4′10″ (127–147 cm)
Stock specs
| Type | Kids |
|---|---|
| Year | 2025 |
| Price when new | $499 |
| Sold at | REI (rei.com) |
| Wheels | 24" × 66 mm tires |
| Gears | 1×7 · 36T · 14–34T |
| Brakes | Tektro Mechanical disc (model not listed) |
| Fork | Co-op Cycles Rigid aluminum fork |
| Rear derailleur | Shimano Tourney 7-speed |
| Shifter | Shimano Tourney Revo twist, 7-speed |
| Crank | Co-op Cycles Alloy 3-piece, 36T (length not listed) |
| Bottom bracket | Generic Cartridge |
| Weight | 28.2 lb (12.8 kg) |
| Sizes | 24in |
| Stock colors | Cascade Green |
Upgrade limits
How far each part can go on this frame, and why. Measure your own bike to confirm the estimated ones.
| Part | Limit | Why |
|---|---|---|
| Widest tire (current wheel size) | 66 mm | Unknown until measured. Your 21 mm internal rims suit roughly 31–55 mm tires. |
| Tubeless | Not recommended | Tubeless needs a rim built to seal (bead hook + channel) and tubeless-ready tires. |
| Valve type | Unknown | Decides which tubes and pump heads fit. Presta tubes fit Schrader rims with a grommet; not the other way. |
| Replacement wheels | Axle unknown · 100/135 mm · 6-bolt disc | Any wheel matching axle type, spacing and brake mount fits. Rear also needs the right freehub. |
| Biggest rear cog | 34T (now 34T) | Set by the rear derailleur (Shimano Tourney 7-speed (model not listed)): max low sprocket 34T, total capacity ?T. A hanger extender can add a few teeth (hit-or-miss on non-Shadow derailleurs); a new derailleur is the reliable way to get more. |
| Front gears | 1x (36T) | One ring, no front derailleur. Adding a front derailleur needs a mount on the seat tube and a 2x crankset, so most riders change the ring size or cassette instead. |
| Chainring size | Unknown (now 36T) | Estimated from similar frames. Measure the chainring-to-chainstay gap to confirm. Check whether your ring is bolted or riveted. Spindle length (? mm) sets chainline; a big change in ring size may need a different BB spindle. |
| Gear count upgrades | Freewheel (≤8) | Threaded freewheel: up to 7/8-speed freewheels only. More speeds needs a new rear wheel with a freehub. |
| Cranks & bottom bracket | Square taper · 68 mm shell · ? mm spindle | Any square-taper crankset fits with the right spindle length. Upgrading to Hollowtech II needs a new BB (same threaded shell). |
| Pedal thread | 9/16" × 20 | Every adult multi-piece crank uses 9/16". One-piece kids/cruiser cranks use 1/2". |
| Brake pads | Shape unknown | Disc pads only fit calipers with the matching shape. |
| Rotor size | ?/? mm now · front up to 180 mm | 6-bolt rotors. Going bigger needs a caliper adapter: adapter type depends on the mount (post, IS or flat). Most steel forks allow 180 mm; check the fork if a max rotor is printed on it. |
| Caliper upgrades | Long-pull (MTB) mechanical | Your levers pull a lot of cable, so upgrade calipers must be long-pull (MTB) versions: TRP Spyke, Juin Tech M1, Avid BB7 MTB. Road calipers (TRP Spyre, BB7 Road) would feel mushy. |
| Stems & bars | ? steerer · ? mm bar clamp | Any stem for a 1-1/8" steerer with a 31.8 mm clamp fits. You can cut a bar narrower but not wider. |
| Drop-bar conversion | Possible with mods | Needs road brake/shift levers (microSHIFT R8 makes 8-speed ones that pull Shimano 8-speed cable correctly), a drop bar, tape, and road-pull brake calipers because road levers pull less cable. Usually $250+. |
| Seatposts | ? mm | Buy posts in exactly this diameter. |
| Racks, fenders, bottles | No rack · No fender · 0 bottle | Threaded eyelets at the dropouts and seat stays take a rack and fenders. Fork leg mounts take cargo cages. |
| Max load (rider + cargo) | 119 lb | Wheels are usually the weak point under heavy loads. Stay under this with rider plus luggage. |
Best upgrades by area
Three options that fit the REI Co-op Cycles REV 24 as-is in each area, from budget to best. ★ marks the one most worth the money. How we pick. Typical US prices, checked October 2026. They change often: check the price at the store.
Upgrades that fit as-is
Brakes
- TRP Spyke mechanical disc calipers, long pull (pair), $$$$. Disc-brake part ↔ your disc brakes · Long-pull caliper ↔ your flat-bar (long-pull) levers
- Juin Tech M1 cable-hydraulic calipers, long pull (pair), $$$. Disc-brake part ↔ your disc brakes · Long-pull caliper ↔ your flat-bar (long-pull) levers
- Jagwire Mountain Pro brake cable kit (Kevlar KEB-SL housing), $$. Made for flat bars ↔ your flat bar
- Shimano Tourney BR-TX805 mechanical disc calipers, long pull, post mount (pair), $$. Disc-brake part ↔ your disc brakes · Long-pull caliper ↔ your flat-bar (long-pull) levers
Comfort
- WTB Volt saddle, $$. Medium-width shape that suits most riders. Measure sit bones if comfort is the goal.
- Brooks C17 All Weather saddle, $$$. Vulcanized rubber top that flexes like a hammock, and this All Weather version is fully waterproof. No break-in like leather. Firm, not padded: made for long…
- Bikeroo oversized comfort saddle, $. Wide, soft and sprung for short upright rides on cruisers and hybrids. On rides over an hour wide padding can chafe; a firmer saddle that fits your sit bones…
- Selle Royal Respiro Moderate saddle, $$$. Made for a 60° "moderate" back angle (most flat-bar hybrids). Very upright cruisers suit the wider Respiro Relaxed. Standard round steel rails.
- Fizik Terra Argo X5 saddle (150 or 160 mm), $$$. Pick 150 mm for narrower sit bones, 160 mm for wider. Round 7 mm alloy rails fit every standard clamp.
- Ergon SR Allroad Core Comp saddle (men's or women's), $$$. Comes in S/M and M/L widths (measure your sit bones) and men's and women's shapes. Round CroMo rails; 120 kg rider limit.
Control
- Race Face Chester composite flat pedals, $$. Big platform with pins. Feet stay put on bumps and in rain. Install with an 8 mm hex key (no wrench flats).
- ROCKBROS aluminum flat pedals, $$. Budget metal platform with pins. A big step up from stock plastic.
- Shimano PD-M520 SPD clipless pedals (cleats included), $$. Nearly indestructible two-sided SPD pedals. You also need SPD (2-bolt) shoes, about $60–100 more. Set the release tension low and practice unclipping before…
- Crankbrothers Stamp 2 aluminum flat pedals (small or large), $$$. Sized by shoe: small for US men's 5–10, large for 10 and up. Grease the threads and tighten to about 35 Nm.
- OneUp Components Aluminum flat pedals, $$$. Bearings and bushings can be serviced with a cheap kit instead of replacing the pedal. Grease the threads and tighten to about 35 Nm.
- Shimano PD-EH500 dual-sided SPD / flat pedals (cleats included), $$$. Comes with SM-SH56 multi-release cleats, which are easier to get out of in a panic. You still need 2-bolt SPD shoes to clip in.
- Shimano Deore XT PD-M8100 SPD pedals (cleats included), $$$. Cup-and-cone bearings are fully serviceable and last for years. Shoes with a 2-bolt SPD cleat sold separately.
Utility
- USB rechargeable front + rear light set, $$. Daytime flashing lights cut collisions. Required by law at night.
- Pletscher adjustable kickstand, $$. Handy for errands. Check it clears the rotor and chainstay.
- Lisen clamp-style handlebar phone mount, $. Cheap and tool-free for maps on paved rides. On rough gravel or trails a locking mount (Quad Lock or Peak Design, about $45–70 plus a case) is much safer.
- Topeak TopLoader top tube bag (0.75 L), $$. Keeps snacks, keys and a multi-tool within reach. Straps on, with a rain cover. Check your knees do not rub it when you stand up.
- Knog Oi Classic bell, $. Slim ring bell that wraps the bar. Large fits 23.8–31.8 mm bars; Small fits 22.2 mm kids and BMX bars. Required by law in some places.
- Planet Bike Beamer 200 + Blinky Squared USB light set, $$. USB rechargeable, tool-free mounts. Use flash mode in daylight. Rear light is 30 lumens: good for town, modest on fast roads.
- Cygolite Metro Plus 800 + Hotshot Pro 150 USB light set, $$$. Nine headlight modes including a daytime flash. Aim the beam slightly down so you do not blind oncoming riders.
- Trek (Bontrager) Ion Pro RT + Flare RT light set, $$$. Daytime-running flash modes on both lights. ANT+ lets a Garmin or Wahoo show battery and switch them. Full power runs about 1.5 hours; medium lasts much longer.
Drivetrain
- KMC X8 8-speed chain with Missing Link, $. 6/7/8-speed chain ↔ your 7-speed drivetrain
- KMC Z7 6/7-speed chain (116 links), $. 6/7-speed chain ↔ your 7-speed drivetrain
- KMC Z8.3 6/7/8-speed chain (116 links), $. 6/7/8-speed chain ↔ your 7-speed drivetrain
- KMC X8 EPT 6/7/8-speed anti-rust chain with Missing Link, $$. 6/7/8-speed chain ↔ your 7-speed drivetrain
Gearing
- Shimano Tourney MF-TZ500-7 7-speed freewheel 14–28, $. 7-speed ↔ your 7-speed drivetrain · 28T biggest cog ↔ your derailleur's 34T max
- Shimano Tourney MF-TZ500-7 7-speed freewheel 14–34 (MegaRange), $. 7-speed ↔ your 7-speed drivetrain · 34T biggest cog ↔ your derailleur's 34T max
- SunRace 7-speed freewheel 13-28 (MFM3S), $. 7-speed ↔ your 7-speed drivetrain · 28T biggest cog ↔ your derailleur's 34T max
- SunRace MF-M300 7-speed freewheel 14-34, $$. 7-speed ↔ your 7-speed drivetrain · 34T biggest cog ↔ your derailleur's 34T max
- Shimano Acera RD-M3020-8 SGS 7/8-speed rear derailleur (40T max), $$. 7-speed ↔ your 7-speed drivetrain · Shimano cable pull ↔ your shifter
Tires
- Kenda K-Rad 24x1.95 (50-507) wire (pair), $$. 50 mm tire ↔ your ~66 mm clearance
- Schwalbe Big Apple 24x2.00 (50-507) (pair), $$. 50 mm tire ↔ your ~66 mm clearance
- Schwalbe Billy Bonkers 24x2.00 (50-507) Addix folding (pair), $$$. 50 mm tire ↔ your ~66 mm clearance
Fits with small changes (12)
- Shimano BR-MT200 hydraulic brake set (pair, levers included), $$$. Replaces your brake levers. Your shifter stays.
- Ergon GP1 ergonomic grips, $$. You have twist shifters: buy the short (Gripshift) version.
- Budget ergonomic lock-on grips, $. You have twist shifters: buy the short (Gripshift) version.
- Shimano BR-MT420 4-piston hydraulic brakes + BL-MT401 levers (pair), $$$. Replaces your brake levers. Your shifter stays.
- Ergon GA3 lock-on grips, $$. You have twist shifters: buy the short (Gripshift) version.
- Ergon GP5 ergonomic grips with built-in bar ends (S or L), $$$. You have twist shifters: buy the short (Gripshift) version.
- Stan's NoTubes tire sealant 16 oz, $. In tubes: needs tubes with removable valve cores (Presta or Schrader to match your rims).
- Orange Seal Endurance tubeless sealant 16 oz, $. In tubes: needs tubes with removable valve cores (Presta or Schrader to match your rims).
- SILCA Ultimate Tubeless Sealant 16 oz, $. In tubes: needs tubes with removable valve cores (Presta or Schrader to match your rims).
- Shimano Deore BL-M6100 + BR-M6100 2-piston hydraulic brake set (pair, levers included), $$$$. Replaces your brake levers. Your shifter stays.
- Shimano Deore BL-M6100 + BR-M6120 4-piston hydraulic brake set (pair, levers included), $$$$. Replaces your brake levers. Your shifter stays.
- Shimano SLX BL-M7100 + BR-M7120 4-piston hydraulic brake set (pair, levers included), $$$$. Replaces your brake levers. Your shifter stays.
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Buying one used? Fair prices
Worked out from the price new ($499), age and condition, not live market data. If it needs tires, a chain or brakes, take off what fixing them would cost.
| Condition | 1 year old | 3 years old | 5 years old |
|---|---|---|---|
| Like new | $305–$400 | $260–$340 | $220–$290 |
| Good | $270–$355 | $225–$300 | $190–$255 |
| Fair | $220–$290 | $185–$245 | $155–$205 |
| Needs work | $170–$220 | $140–$185 | $120–$160 |
See what these really sold for on eBay · Other used bike prices
Geometry (size 24in)
| Stack | 488° |
|---|---|
| Reach | 352 mm |
| Head angle | 69° |
| Seat angle | 72° |
| Chainstay | 410° |
| Wheelbase | 969 mm |
| Seat tube | 290 mm |
| Standover | 586° |
Compare with
- Huffy Rock It 20" · compare frames side by side
- Trek Precaliber 20 · compare frames side by side
- Specialized Hotrock 24 · compare frames side by side
- woom ORIGINAL 4 · compare frames side by side
Sources: REI: Co-op Cycles REV 24 Kids' Mountain Bike (215698) specs + size chart · Two Wheeling Tots: REI REV kids bikes review (2026 redesign seat heights + weights)