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Eddy Merckx 525R vs Storck Aerfast.4 Red Edition
Pick up to 4 bikes. Rows line up component by component. Highlighted rows differ, and green marks the best value where lower or higher is clearly better.
Key differences
- The Eddy Merckx 525R starts €500 cheaper (€6,799 vs €7,299 for the Storck Aerfast.4 Red Edition).
- Our verdict scores the Eddy Merckx 525R higher overall: 80/100 vs 71/100.
- Tire clearance: up to 34 mm on the Eddy Merckx 525R vs 28 mm on the Storck Aerfast.4 Red Edition.
- The Eddy Merckx 525R comes in 4 sizes, the Storck Aerfast.4 Red Edition in 6.
Eddy Merckx 525R
Storck Aerfast.4 Red Edition
| Eddy Merckx525R | StorckAerfast.4 Red Edition | |
|---|---|---|
| Overview | ||
| Brand | Eddy Merckx | Storck |
| Build | 525R Campagnolo Super Record 2x13 | Aerfast.4 Red Edition Red eTap AXS D1 |
| Build notes | Pre-configured 'collection' bike (design 52R01BS, silver secondary colour) in sizes XS-L; Merckx also builds it to order in its configurator. EUR price from the Belgian store, GBP from the UK store. Pedals not included. | Fixed build with the previous-generation SRAM Red AXS (D1) and Zeitjaeger Comp 55R wheels, sizes XS-M. MSRP €7,299; Storck showed it reduced to €5,499 on 2 Nov 2026. Price from Storck's own web shop (EUR only). No power meter. |
| Price (MSRP) | €12,999€12,999£11,499 | €7,299€7,299€7,299 |
| Model year | 2026 | 2026 |
| Generation | 525R (2026) | Aerfast.4 (fourth generation) |
| Launched | 2026-06 | 2021 |
| Newer generation | — | Aerfast.5 (2024) |
| Discipline | Aero road | Aero road |
| UCI legal | Yes | Yes |
| Verdict (out of 100) | ||
| Overall score | 80 | 71 |
| Aero | 86 | 86 |
| Frame | 88 | 74 |
| Components | 84 | 76 |
| Fit | 74 | 58 |
| Practicality | 72 | 58 |
| Price | 75 | 71 |
| Frame & fork | ||
| Frame material | High-modulus carbon | Carbon (CFR/UD), Red Edition frame |
| Fork material | Carbon, asymmetric with a diffuser-style crown | — |
| Frame weight | 952 g33.6 oz | 950 g33.5 oz |
| Fork weight | — | 500 g17.6 oz |
| Frameset weight | — | 1,900 g4.19 lb |
| Weight measured on | Size M (Eddy Merckx); finish not stated | Storck's 'from' weights on its Aerfast.4 Platinum and Pro frameset pages (frame, fork, one-piece cockpit; frameset includes seatpost and headset); not split by grade or size |
| Max system weight | 110 kg242.5 lb | 120 kg264.6 lb |
| Frame sizes | XS, S, M, L | XS, S, M |
| Colours | Collection designs 52R01AS (grey with red) and 52R01BS (silver secondary colour); further designs in the configurator | Black with red accents (Storck names no colour) |
| Also available as | — | Aerfast.4 Platinum, Pro, Comp and Red Edition (frame classes of the same design, same geometry); succeeded by the Aerfast.5 |
| UCI frame approval | Approved 3 Nov 2025 as '525R' (frame and fork), sizes XS-L (4), code EMC-015 (UCI list version 2026.10.02) | On the UCI list of approved framesets as 'AERFAST.3 / AERFAST.4' (code STOR-AEF), approved 8 Feb 2023 in sizes XS-XXL (6) (UCI list version 2026.10.02); the list doesn't distinguish the grades |
| Compatibility & standards | ||
| Brake type | Flat mount disc | Hydraulic disc, flat mount (160 mm rotors front and rear as built) |
| Wheel size | 700c | — |
| Max tire width | 34 mm | 28 mm |
| Bottom bracket standard | — | Press-fit, 41 mm bearing bore x 86.5 mm |
| Drivetrain compatibility | UDH rear derailleur interface for all current road drivetrains; Merckx builds it with Shimano Di2, SRAM AXS (2x and XPLR 1x) and Campagnolo Super Record Wireless | — |
| 1x compatible | Yes | — |
| Front derailleur mount | Removable braze-on hanger | — |
| Cable routing | — | Internal through the one-piece cockpit |
| Fit & adjustability | ||
| Cockpit | One-piece Forza Nimbus Pro bar and stem (360 mm at the hoods, 400 mm in the drops); wider cockpit options offered | One-piece Storck RBSU Aerfast.4 bar and stem, one size per frame size |
| Seatpost type | Slim 525R aero carbon post (370 mm, 0 mm offset) with integrated clamp | Storck Aerfast.4 carbon aero seatpost |
| Fit notes | Four sizes with a progressive geometry: seat angle 74.5° (XS) to 76° (L) and reach 377-437 mm, so riders keep the same hip angle and saddle setback relative to the bottom bracket in every size and can use standard stem lengths. | Each frame size comes with one cockpit size, from 380 mm bar / 90 mm stem (XS) to 440 / 120 mm (XXL). Storck says a computer mount and triathlon extensions can be retrofitted, and lists its TT kit as compatible with the Aerfast.4. |
| Aerodynamics | ||
| Manufacturer aero claims | 9% less aerodynamic drag than the previous 525; deep head tube to the UCI limit, a down tube profiled to work with bottles, an asymmetric fork for crosswinds and a diffuser-style fork crown | Storck says the Aerfast.4 measured 199 W at 45 km/h in TOUR's wind-tunnel test; TOUR's own figures were 201 W for the Pro Disc and 202 W for the Comp Disc |
| Testing method | Position and geometry validated in the Aero Performance Lab wind tunnel; Merckx publishes no drag numbers | Wind tunnel |
| Tube profile | Down tube based on Ridley's Noah aero platform; slim seat stays | 80 mm wide aero fork with a camtail trailing edge |
| Travel, maintenance & warranty | ||
| Headset bearings | CeramicSpeed SLT bearings (lifetime warranty) | — |
| Derailleur hanger | UDH | — |
| Proprietary parts | Forza Nimbus Pro cockpit, 525R seatpost | RBSU Aerfast.4 one-piece cockpit, Aerfast.4 seatpost and headset |
| Frame warranty | Lifetime, transferable, after registration within 30 days of purchase; requires annual servicing at an authorised dealer | — |
| Sold via | Through Eddy Merckx dealers and the brand's online store; configurable to order | Direct from Storck's web shop and Storck stores |
| Drivetrain | ||
| Groupset | Campagnolo Super Record Wireless | SRAM Red eTap AXS D1 |
| Launched | 2023 · current generation | 2019 · replaced by SRAM Red AXS E1 (2024) |
| Speeds | 13-speed | 12-speed |
| Electronic | Yes | Yes |
| Wireless | Yes | Yes |
| Drivetrain | 2x | 2x |
| Shifters | Campagnolo Super Record Wireless | — |
| Crankset | Campagnolo Super Record 13 | SRAM Red eTap AXS D1 |
| Chainrings | 52/36 | 48/35 |
| Crank length | 170 (size M) | — |
| Bottom bracket | — | Storck Press-fit 41 x 86.5 mm |
| Standard | — | Press-fit, 41 mm bearing bore x 86.5 mm |
| Front derailleur | Campagnolo Super Record Wireless | SRAM Red eTap AXS |
| Rear derailleur | Campagnolo Super Record Wireless | SRAM Red eTap AXS D1 |
| Cassette | Campagnolo Super Record Wireless | SRAM Red |
| Range | 11-32 | 10-33 |
| Speeds | 13-speed | 12-speed |
| Chain | Campagnolo Super Record Wireless | SRAM Red |
| Brakes | ||
| Brake calipers | — | SRAM Red |
| Type | — | Hydraulic disc, flat mount |
| Notes | — | 160 mm rotors front and rear |
| Wheels & tires | ||
| Wheelset | Campagnolo Bora WTO 45 | Storck Zeitjaeger Comp 55R |
| Front rim depth | 45 mm | — |
| Rear rim depth | 45 mm | — |
| Material | Carbon | Carbon |
| Tires | Vittoria Corsa Pro TLR G2.0 | Continental Grand Prix 5000 S TR |
| Tire width | 30 mm | 28 mm |
| Set up tubeless | Yes | — |
| Cockpit | ||
| Handlebar | Forza Nimbus Pro | Storck RBSU Aerfast.4 |
| Type | One-piece carbon bar and stem | One-piece bar and stem |
| Integrated stem | Yes | Yes |
| Bar width | 360 mm | — |
| Widths available | 360 mm c-c at the shifters, 400 mm c-c in the drops; Merckx offers wider alternatives | 380 mm / 90 mm stem (XS), 400/100 (S), 420/100 (M-L), 420/110 (XL), 440/120 (XXL) |
| Notes | 110 mm stem on the size M spec; stem length by size isn't listed. Stealth Black. | — |
| Headset | — | Storck Aerfast.4 integrated headset |
| Saddle & seatpost | ||
| Saddle | Selle Italia SLR Boost Superflow 3D | Fizik Vento Argo R5 |
| Rails | Carbon | — |
| Seatpost | Eddy Merckx 525R | Storck Aerfast.4 Carbon |
| Offset / setback | 0 mm | — |
| Material | Carbon | Carbon |
| Notes | 370 mm aero post with integrated clamp (Deda) | — |
| Bar tape | — | Storck Microfibre |
| Notes | — | Black |
| Geometry (smallest – largest size) | ||
| Sizes | XS, S, M, L | XS, S, M, L, XL, XXL |
| Rider height min | — | 152–188 cm5′0″–6′2″ |
| Rider height max | — | 166–190 cm5′5″–6′3″ |
| Stack | 535–593 mm21.1–23.3″ | 482–576 mm19–22.7″ |
| Reach | 377–437 mm14.8–17.2″ | 362.5–418 mm14.3–16.5″ |
| Seat tube angle | 74.5–76° | 73° |
| Head tube angle | 73° | 70–72° |
| Head tube length | 125–185 mm4.9–7.3″ | 85–170 mm3.3–6.7″ |
| Effective top tube | 525–585 mm20.7–23″ | 510–595 mm20.1–23.4″ |
| Seat tube length | 480–540 mm18.9–21.3″ | 458–583 mm18–23″ |
| Chainstay | 407 mm16″ | 410 mm16.1″ |
| Wheelbase | 964–1,043 mm38–41.1″ | — |
| BB drop | 75 mm3″ | — |
| Standover | 698–756 mm27.5–29.8″ | — |
| Crank length | — | 170–175 mm6.7–6.9″ |
| Stem length | — | 90–120 mm3.5–4.7″ |
| Handlebar width | — | 380–440 mm15–17.3″ |
Geometry overlay
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