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 Most makers do not publish it, so I assume 15 mm and add 6 mm to the band, which on its own is enough to hold an answer at "probably" rather than "fits".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 Spear
Aero road · 7 sizes
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This is the bike I ride
No account is needed to read the table. Report a wrong number · Correct this bike
- Bike
- Seka Spear · 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) |
|---|---|---|---|---|---|---|---|---|
| XS | 508 | 362 | 70.6 | 75 | 107 | 410 | 969 | 725 |
| S | 524 | 370 | 71.7 | 74.8 | 120 | 410 | 973 | 738 |
| M | 543 | 379 | 72.9 | 74 | 136 | 410 | 973 | 759 |
| MR | 538 | 386 | 73 | 74 | 130 | 410 | 978 | 753 |
| L | 570 | 389 | 73 | 73.5 | 164 | 410 | 990 | 786 |
| LR | 560 | 397 | 73.1 | 73.5 | 153 | 410 | 995 | 774 |
| XL | 600 | 402 | 73.5 | 73 | 193 | 410 | 1008 | 814 |
The table runs on to the right: 6 more columns after Reach. Scroll it sideways to read them.
The MR 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 SEKA's Rapier one-piece integrated handlebar: the maker's page says widths 360 to 415 mm and stem lengths 80 to 130 mm, "19 sizes to choose from freely" (the Rapier size table on the maker's site is an image, https://www.sekabikes.com/wp-content/uploads/2024/10/Rapier-%E5%B0%BA%E5%AF%B8-EN-33.png, not read here).
Cockpit and seatpost, in the maker's words · 149 words
Frameset with SEKA's Rapier one-piece integrated handlebar: the maker's page says widths 360 to 415 mm and stem lengths 80 to 130 mm, "19 sizes to choose from freely" (the Rapier size table on the maker's site is an image, https://www.sekabikes.com/wp-content/uploads/2024/10/Rapier-%E5%B0%BA%E5%AF%B8-EN-33.png, not read here). The development manual says "19 integrated bar sizes, 2 seatpost sizes" (two seatpost offsets). Frame: RDC layup 685 g or Standard 780 g (729 g +/-35 g M size Shadow Black painted), BSA threaded 68 mm bottom bracket, headset bearings upper and lower 49.5x40.5x6.5 mm 45/45 deg, axles front 118.6 mm M12xP1.0 and rear 165.2 mm M12xP1.5, max tyre 32 mm actual, saddle clamp for 7x7 / 7x9 / 7x10 / 7x11 rails, 700c. 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 (bar size is a buyer's choice).
SOURCE: SEKA (sekabikes.com) publishes the Spear geometry only inside its Chinese development manual PDF (linked from the maker's CN home page as "SEKA-Spear-产品开发手册.pdf", 32 pages, 10.0 MB). Source: pdf_table (the maker's own Chinese-language Spear product development manual, "SEKA-Spear-产品开发手册.pdf", linked from
How I read the maker's table
page 25 carries the table as text, so every number was extracted by script from the PDF text layer, not read from a picture, and checked against a 2x render of the page. SIZES: SEKA's "5+2 non-linear geometry": five regular sizes XS/S/M/L/XL plus two Racing sizes MR (between M and L: more reach than M, less stack) and LR (between L and XL); the table order is XS, S, M, MR, L, LR, XL and is kept. Consistency check (mine, not published): sqrt(FC^2 - H^2) + sqrt(RC^2 - H^2) reproduces WB within 0.5 mm on every size (XS 565.2 + 403.3 = 968.5 vs 969; XL 603.7 + 403.6 = 1007.3 vs 1008). MODEL YEAR: not stated in the PDF or on the page; the manual was uploaded 2024-05 and the Spear launched in 2024; null. Category aero road (the maker: aerodynamic race frame, "Air Drag -6 W" vs the Exceed). No aggregator consulted.
Source: pdf_table (the maker's own Chinese-language Spear product development manual, "SEKA-Spear-产品开发手册.pdf", linked from https://www.sekabikes.com/ ; page 25 "车架几何&身高尺码对照表" (frame geometry and height size chart) carries the table as a real text layer, extracted by script; the English product page https://www.sekabikes.com/en/spear-en-2/ publishes no geometry table, only a size-recommendation chart image, and its "Spear white paper" link returns HTTP 404. PDF not stored)