Stack and reach
How high and how far forward the top of the head tube is, from the bottom bracket. They are the two numbers that decide whether a frame can be set up like yours.
BB, or bottom bracket
The axle your cranks turn on, in the middle of the frame. Every number on this site is measured from it, because it is the one point that sits in the same place on every bike.
Headset cover
The little cap on top of the head tube, under your spacers. Most makers do not publish it, so I assume 15 mm and add 6 mm to the band, which on its own is enough to hold an answer at "probably" rather than "fits".
Stem clamp, and its centre
The collar on the steerer that your stem bolts to. I need the middle of it. Where a maker gives only the height, I assume halfway up and say so on the answer.
Steerer
The tube coming up out of the fork. The cover, the spacers and the stem all sit on it, and it is the thing a mechanic cuts to length.
Bar reach
How far forward the hoods sit from the middle of the bar. Two bars on the same stem can put your hands 20 mm apart, which is why I ask.
Setback
How far your saddle sits behind the bottom bracket.
Drop
How much lower your bar is than your saddle.
Rails, and the rail centre
The two rods under your saddle, and the middle of the straight part of them. That midpoint is the point I use, because it is the one you can find with a tape.
The band
How far out I could be, in millimetres, and why. It is a straight sum of everything I had to assume rather than a clever average, so it errs wide on purpose.
wb, stand, trail
Wheelbase, standover and trail: how long the bike is, how high the top tube is where you straddle it, and how steady the steering feels. I show them against your bike, and I leave them out when the maker does not publish them.
est.
Estimated: a number I worked out rather than read off the maker's table. Anything marked this way can move if the maker publishes the real one.
Close Escape closes it. The measuring guide has the pictures. Open the measuring guide
Seka ExAero
Aero road · 7 sizes
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This is the bike I ride
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- Bike
- Seka ExAero · Aero road · 7 sizes · integrated cockpit
- Geometry
- sekabikes.com, fetched 29 Aug 2026, re-checked, no differences
- Cockpit
- Generic stem and bar, assumed
- Solved with
- cover 15 mm (assumed), max spacers 40 mm (assumed), stem clamp centre 20 mm (assumed), so every verdict carries ±10 mm at the bar
- Sheet
- 6 September 2026 · 210 bikes, 43 makes, 1,262 sizes in the catalogue
Geometry, every size, from the maker's table
The tinted row is the size drawn beside it. Press a size to draw it.| Size | Stack (mm) | Reach (mm) | Head angle (deg) | Seat angle (deg) | Head tube (mm) | Chainstay (mm) | Wheelbase (mm) | Standover (mm) |
|---|---|---|---|---|---|---|---|---|
| 44 | 502 | 365 | 70.5 | 75.5 | 99 | 408 | 967 | 716 |
| 49 | 512 | 371 | 71.4 | 75.5 | 106 | 408 | 969 | 725 |
| 52 | 526 | 377 | 72.4 | 74 | 118 | 408 | 971 | 739 |
| 54 | 542 | 383 | 73 | 74 | 133.7 | 408 | 974 | 757 |
| 56 | 563 | 391 | 73.2 | 73.5 | 154.4 | 408 | 986 | 776 |
| 58 | 586 | 399 | 73.4 | 73.5 | 177.7 | 408 | 999 | 797 |
| 61 | 612 | 406 | 73.6 | 73 | 205 | 408 | 1012 | 822 |
The table runs on to the right: 6 more columns after Reach. Scroll it sideways to read them.
The 54 drawn to scale from the table, with no build on it. Stack and reach run from the bottom bracket to the top of the head tube; every size is solved from those two. One square is 100 mm.
The maker's cockpit
No stock cockpit I can name, so every size is solved on a generic stem and bar unless you choose one on the sheet.Generic stem and barAssumedNo bar is listed for this frame.
In the maker's words
Kept whole, as I read it off sekabikes.com.Frameset with the SEKA Gladius one-piece integrated cockpit in two versions, standard and ALTA riser: "The ALTA version adds 25 mm of stack while maintaining the same reach", each in 19 sizes; weights Gladius (375x100) about 320 g, ALTA (375x100) about 335 g; stem lengths and widths are not listed on the page (the white paper wind-tunnel setup names a "375x100" bar).
Cockpit and seatpost, in the maker's words · 144 words
Frameset with the SEKA Gladius one-piece integrated cockpit in two versions, standard and ALTA riser: "The ALTA version adds 25 mm of stack while maintaining the same reach", each in 19 sizes; weights Gladius (375x100) about 320 g, ALTA (375x100) about 335 g; stem lengths and widths are not listed on the page (the white paper wind-tunnel setup names a "375x100" bar). Frame: RDC 820 g or STD 935 g (54 cm, +/-35 g, unpainted), BSA threaded 68 mm bottom bracket, headset bearings upper and lower 49.5x40.5x6.5 mm 45/45 deg, 12x100 / 12x142 thru-axles, 32 mm tyre clearance, integrated seat clamp for 7x7 / 7x9 / 7x10 rails, UDH, ExAero MAG magnetic aero bottles, "Wind Eye" seat tube cut-out. Stem angle, bar reach and drop, spacer heights, max spacer stack and top-cover height are not published on the pages fetched. stock_stem_length / stock_bar_width null.
SOURCE: SEKA's ExAero White Paper (42 pages, 9.7 MB, uploaded 2026-08), page 31, section "5 Geometry": a table with columns SIZE, STACK, REACH, TRAIL, C1, RC, H, FC, WB, L, N, Q1, Q7, F, G, STANDOVER (mm) for sizes 44/49/52/54/56/58/61. Source: pdf_table (the maker's ExAero White Paper PDF, linked from
How I read the maker's table
The table is a raster picture inside the PDF (PyMuPDF extracts only the words "Geometry", "REACH", "N", "STANDOVER" from that page), so every number was read by eye from a 4x render (2382x3368 px page, table cropped to 1549x455 px) and checked twice. The EN product page https://www.sekabikes.com/en/exaero-2/ has a "View Geometry Chart" link and a size-recommendation image (seka_recommended_height_chartV2.png: XS 150-163, S 160-173, M 170-180, MR 170-185, L 177-188, LR 180-194, XL 185-198 cm) but no table in its HTML. The white paper says the ExAero replaces the Spear's 5+2 sizing with "a more closely spaced and linear seven-size range" (44 to 61), that chainstays went from 410 to 408 mm with more BB drop, and that "ExAero and Proto A in size 54 both use a frame geometry of 542 mm stack and 383 mm reach", which matches the table. Consistency check (mine, not published): sqrt(FC^2 - H^2) + sqrt(RC^2 - H^2) reproduces WB within 0.5 mm on every size (44: 566.1 + 401.0 = 967.1 vs 967; 61: 610.8 + 401.6 = 1012.4 vs 1012). Head tube lengths and top tubes are printed to 0.1 mm as shown. MODEL YEAR: 2026 (the white paper, product page assets and launch are all dated 2026-08; the page title "ExAero EN V2"). Category aero road. No aggregator consulted.
Source: pdf_table (the maker's ExAero White Paper PDF, linked from https://www.sekabikes.com/en/exaero-2/ ; the geometry table on page 31 "5 Geometry" is embedded as a picture (the page's text layer holds only the headings), so the numbers were read by eye from a 4x render of the page; PDF and render NOT stored)