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 Most makers do not publish it, so I assume 15 mm and add 6 mm to the band, which on its own is enough to hold an answer at "probably" rather than "fits".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 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
Cannondale Synapse Carbon
Endurance 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
- Cannondale Synapse Carbon · Endurance road · 7 sizes · integrated cockpit
- Geometry
- cannondale.com, fetched 20 Oct 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
- 22 October 2026 · 686 bikes, 74 makes, 3,984 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 | 510 | 366 | 69.8 | 73 | 91 | 425 | 1003 | 714 |
| 48 | 530 | 371 | 70.9 | 73 | 108 | 425 | 1005 | 722 |
| 51 | 550 | 376 | 71.3 | 73 | 127 | 425 | 1013 | 752 |
| 54 | 570 | 381 | 71.3 | 73 | 150 | 425 | 1026 | 785 |
| 56 | 590 | 387 | 71.3 | 73 | 171 | 430 | 1044 | 815 |
| 58 | 610 | 393 | 71.3 | 73 | 196 | 430 | 1058 | 843 |
| 61 | 640 | 402 | 71.3 | 73 | 227 | 430 | 1077 | 878 |
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.Cannondale SystemBar R-OneVendor-listedstem -6 · reach 80 · drop 130 · lengths 90-120 · widths 380-420
Stock stem and bar per size44 90 x 380, 48 90 x 400, 51 90 x 400, 54 100 x 420, 56 100 x 420, 58 110 x 420, 61 110 x 420 (stem length x bar width, mm)
Frame facts
not read off the maker's page yet: cannondale.com- Tyre clearance
- not recorded yet
- Bottom bracket
- not recorded yet
- Axles and brakes
- not recorded yet
- UDH
- not recorded yet
- Seatpost
- not recorded yet
- Frame weight
- not recorded yet
In the maker's words
Kept whole, as I read it off cannondale.com.The Synapse LAB71 SmartSense ships with Cannondale's one-piece SystemBar R-One (https://www.cannondale.com/en-gb/gear/components/handlebars/carbon-handlebars/systembar-r-one-carbon-one-piece-handlebar).
Cockpit and seatpost, in the maker's words · 60 words
The Synapse LAB71 SmartSense ships with Cannondale's one-piece SystemBar R-One (https://www.cannondale.com/en-gb/gear/components/handlebars/carbon-handlebars/systembar-r-one-carbon-one-piece-handlebar). SystemBar R-One: bar reach 80 mm; drop 130 mm; flare 20 mm (printed in mm); stem angle -6 deg; stem lengths 90/100/110/120 mm; widths 380/400/420 mm; 415 g; Delta steerer, electronic shifting only. Seatpost: "Cannondale C1 Aero 27 Carbon, SmartSense compatible, 330mm length, 0mm offset (44-48cm), 15mm offset (51-61cm)".
OFFICIAL SOURCE: Cannondale GB product pages for the Synapse LAB71 Frameset (SalsifyId 3789-COLL2025) and the Synapse LAB71 SmartSense (3776-COLL2025), both MY2025 in the product data feed. Source: image_table (official Cannondale GB product page, "Geometry" section is a single image
How I read the maker's table
both show the same geometry image, c25_synapse_geotable, headed "Synapse Carbon". The GB Synapse menu lists only the carbon Synapse. The data feed carries Geometry null for every variant, so the image is the only table. SIZE LABELS: the table header prints 44.0/48.0/51.0/54.0/56.0/58.0/61.0; the shop's size selector and the spec text say 44/48/51/54/56/58/61, which is what size_label holds. UNITS: lengths printed in centimetres to one decimal; every length here is the printed value x 10, angles as printed. STACK DATUM: O is drawn to a horizontal through the top of the head tube where G starts; no headset cover drawn. MAKER TYPOS (in the spec text, not the table): the fork is printed "1-1/8" to 1-1/5" Delta steerer" where the headset line says "1-1/8" - 1-1/2""; the SystemBar size list prints "(44m)" for size 44. tyre_width_mm 32 is the LAB71 SmartSense's stock tyre ("Vittoria Corsa PRO Control, 700x32c"), not a table number. stock_stem_length and stock_bar_width are that build's SystemBar R-One sizes per frame size; posts are the seatpost offsets its spec lists per size. The model year printed nowhere on the table; 2025 is the data feed's ModelYear for both pages. STOCK COCKPIT WORDS (moved here from cockpit_options so the cockpit reader does not take a size for a name): the Synapse LAB71 SmartSense Handlebar line reads "Cannondale SystemBar R-One - low drag, full carbon integrated bar/stem, internal routing: 90x380mm (44m), 90x400mm (48-51cm), 100x420mm (54-56cm), 110x420mm (58-61cm)" ("44m" sic, size 44).
Source: image_table (official Cannondale GB product page, "Geometry" section is a single image: https://www.cannondale.com/-/media/images/my25/bikes/road/endurance/synapse-carbon/pdps/c25_synapse_geotable.ashx, 2476x3704 px, diagram + table headed "Synapse Carbon"; numbers read from the image by the collector, image NOT stored)