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 Most makers do not publish it, so I assume 10 mm and add 6 mm to the band beside every answer.
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 hands sit than your saddle. On a riser bar I count the bar's rise, so the drop is that much less than it is to the clamp.
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
Orro Terra X
Gravel · 5 sizes
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This is the bike I ride
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- Bike
- Orro Terra X · Gravel · 5 sizes
- Geometry
- orrobikes.com, fetched 22 Oct 2026, read off the maker's chart, re-checked, no differences
- Seat angle convention
- Calculated from Orro's table
- Cockpit
- Generic stem and bar, assumed
- Solved with
- cover 10 mm (assumed), max spacers 40 mm (assumed), stem clamp centre 20 mm (assumed), so every verdict carries ±10 mm at the bar
- Sheet
- 22 October 2026 · 879 bikes, 79 makes, 4,979 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.The table runs on to the right: 6 more columns after Reach. Scroll it sideways to read them.
The M 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.
Frame facts
read off the maker's page: orrobikes.com- Tyre clearance
- not published
- Bottom bracket
- BB86
- Axles and brakes
- not published
- UDH
- not published
- Seatpost
- not published
- Frame weight
- not published
In the maker's words
Kept whole, as I read it off orrobikes.com.Terra X GRX400 build on the page: FSA Adventure Compact handlebar and FSA Omega ST stem, ORRO alloy setback seatpost; the chart prints no stem or bar sizes, so stock fields are null.
Cockpit and seatpost, in the maker's words · 33 words
Terra X GRX400 build on the page: FSA Adventure Compact handlebar and FSA Omega ST stem, ORRO alloy setback seatpost; the chart prints no stem or bar sizes, so stock fields are null.
OFFICIAL SOURCE: Orro Bikes' own site (orrobikes.com), product page "Terra X GRX400" (frame and fork ORRO Terra X, BB86 bottom bracket per the build list). Source: image_table (official Orro product page "Terra X GRX400", the size chart image "Terra-X-Size-Chart.jpg" read at full resolution; fetched 2026-10-22
How I read the maker's table
Five sizes XS to XL. Not the Terra C chart (orro-terra-c), though stack, reach, head tubes and wheelbases are the same: top tubes 532/584/612 against 529/581/604 on S, L and XL, seat angles 74.5/73.0/72.3 against 74.9/73.3/72.6, L chainstay 422 against 422.5. Bike Insights' Terra X 2023 entry prints the Terra C numbers instead. Not printed: fork offset, standover, front centre, trail, stem and bar (null); stack datum not stated (null). Model year: the listing on the fetch date, so model_year null.
Source: image_table (official Orro product page "Terra X GRX400", the size chart image "Terra-X-Size-Chart.jpg" read at full resolution; fetched 2026-10-22, HTTP 200)