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 Most makers do not publish it, so I assume 15 mm and add 6 mm to the band, which on its own is enough to hold an answer at "probably" rather than "fits".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
Velobuild VB-R-218
Aero road · 8 sizes
Sign in and add the bike you ride, and this table will say what each size needs for your position.
Sign in
This is the bike I ride
No account is needed to read the table. Report a wrong number · Correct this bike
- Bike
- Velobuild VB-R-218 · Aero road · 8 sizes · integrated cockpit
- Geometry
- velobuild.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)not published | Standover (mm)not published |
|---|---|---|---|---|---|---|---|---|
| XXXS-450 | 518 | 365 | 70.5 | 74.4 | 104 | 406 | ||
| XXS-465 | 525 | 372 | 71.4 | 74 | 109 | 406 | ||
| XS-485 | 532 | 378 | 72 | 73.7 | 114 | 406 | ||
| S-500 | 542 | 383 | 72.5 | 73.7 | 123 | 406 | ||
| M-510 | 551 | 385 | 72.8 | 73.4 | 131 | 408 | ||
| L-520 | 562 | 389 | 72.8 | 73.4 | 142 | 408 | ||
| XL-525 | 570 | 391 | 73.2 | 73 | 149.5 | 408 | ||
| XXL-540 | 585 | 396 | 73.7 | 73 | 163 | 408 |
The table runs on to the right: 6 more columns after Reach. Scroll it sideways to read them.
The M-510 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 velobuild.com.Frameset includes: Frame, Fork, Seat Post, Seat Post Clamp, Headset, axles and Integrated bar (page wording), full internal cables.
Cockpit and seatpost, in the maker's words · 195 words
Frameset includes: Frame, Fork, Seat Post, Seat Post Clamp, Headset, axles and Integrated bar (page wording), full internal cables. INTEGRATED one-piece bar/stem, sizes written as width/stem in mm: 400/90, 400/100, 400/110, 400/120; 420/90, 420/100, 420/110, 420/120; 440/90, 440/100, 440/110, 440/120 (the description literally prints the tenth entry as 400/100, an evident typo for 440/100; the purchase option list on the same page does include 440/100). Purchase options live on the page at fetch time: Integrated bar size 420/90, 440/90, 440/100, 440/110, 440/120 (the other seven combinations are not offered any more); Frame Size XXS and XS only (product flagged out of stock in the page metadata); Bottom Bracket BSA; Finish Glossy or Matte; 1.5k and UD carbon weave mentioned in the meta description. Bar reach 80 mm, bar drop 125 mm, bar weight 370 g. Stem angle, stem/bar clamp height, spacer heights and maximum spacer stack NOT published. Headset: top 1-1/2 in, down 1-1/2 in (page text). Seat post: proprietary aero seat post included with clamp, 170 g; seat post offset/setback NOT published. No default bar size is stated, so stock_stem_length and stock_bar_width are null. Weights (size M): frame about 1100 g, fork 410 g.
STACK/REACH DATUM: the chart diagram draws K (Stack) as the vertical from the bottom bracket centre to the top of the head tube and J (Reach) as the horizontal from the BB centre line to the same head tube top point, i.e. Source: image_table (geometry chart image embedded in the product description
How I read the maker's table
the usual BB-centre to head-tube-top convention. Column A is BB center to top of seattube (stored as seat_tube_length). Column B is Effective top tube horizontal. Column C BB offset is printed as -72 mm for every size; stored here as bb_drop 72 (positive drop, same convention as the other files). Column G Front center is stored as front_centre. Column I Fork offset is 43 mm for every size. Head tube length for XL is printed 149.5. SIZE NAMING: the chart labels rows XXXS-450, XXS-465, XS-485, S-500, M-510, L-520, XL-525 and XXL-540; the number after the hyphen does NOT equal column A (465, 500, 515, 530, 540, 550, 560, 575) and its meaning is not explained, so labels are kept verbatim. The chart has 8 rows including XXXS-450, while the page text says Size XXS XS S M L XL XXL available (7 sizes) and only XXS and XS are purchasable at fetch time. NOT PUBLISHED (null): wheelbase, standover, trail, stock stem length and bar width. The chart diagram also shows rear dropout spacing 142 (+1.5/-0) mm, front 100 (+1.5/-0) mm and BSA BB 68L. Page facts: 142x12 rear, 12x100 front, flat mount, 160 mm rotors front and rear, max tyre 32 mm, braze-on front derailleur. MODEL YEAR: the page title and description both say 2022 VB-R-218; the chart image path is dated 2024-01 (a later re-upload) and the gallery images 2022-10. Brand writes its own name VeloBuild; product id 345 on the site. Collected via one curl request to the product page with a browser User-Agent (HTTP 200), then three image downloads from the ueeshop CDN with 2 s pauses; no aggregator consulted.
Source: image_table (geometry chart image embedded in the product description: https://ueeshop.ly200-cdn.com/u_file/UPBA/UPBA916/2401/04/photo/218Geometry.jpg, 825x701 JPEG, read by eye from the image; the surrounding description is plain HTML text)
