KTM labels its road frames in centimetres, the way Italian brands do, and then maps each number to a letter. A 55 is an M, a 57 is an L. The current road range runs on three platforms: the carbon Revelator Alto, the carbon Revelator Syro and the alloy Revelator 10 and 15. The one thing to know before you start is that the number on the seat tube tells you very little on its own. At size 55 the Syro sits 23 mm taller in stack than the Alto, which is the difference between a race position and an endurance one. Browse all KTM bikes at Bikeroom.
Please note. These sizes are indicative and a starting point, not a guarantee of fit. KTM publishes one body height chart for its whole road range and labels it a rough indication. Read it together with the stack and reach numbers below, then confirm against a bike fit or against a bike you already ride.
Quick size finder
KTM's frame sizes page carries a single chart for the road category, covering sizes 49 to 59. Find your height, then read across.
| Rider height | Leg length (inseam) | Revelator Alto | Revelator Syro | Revelator 10 and 15 |
|---|---|---|---|---|
| 150 to 164 cm | 68 to 74 cm | 49 (XS) | 49 | 49 (XS) |
| 165 to 169 cm | 74 to 77 cm | 52 (S) | 52 | 52 (S) |
| 170 to 174 cm | 77 to 80 cm | 55 (M) | 55 | 55 (M) |
| 175 to 179 cm | 80 to 83 cm | 55 (M) | 55 | 55 (M) |
| 180 to 184 cm | 83 to 87 cm | 57 (L) | 57 | 57 (L) |
| 185 to 189 cm | 87 to 90 cm | 57 or 59 | 57 or 59 | 57 or 59 |
| 190 to 194 cm | 90 to 94 cm | 59 (XL) | 59 or 61 | 59 (XL) |
KTM publishes body height only. The inseam column is our own cross check, not KTM data, and the Syro's extra 46 and 61 sizes sit outside KTM's chart. Where height and inseam disagree, trust the inseam for standover. Trust stack and reach for the position you will actually hold.
How to measure yourself
Height. Stand barefoot against a wall, heels together, looking straight ahead. Rest a flat object on your head, level against the wall, then measure from the floor to that mark.
Leg length (inseam). Barefoot, feet about 15 cm apart, press a hardback book up into your crotch as a saddle would sit. Keep it level, mark the top edge and measure down to the floor.
The quick formula. KTM sizes in centimetres, so multiply your inseam in cm by 0.66 and match the result to the nearest KTM number. An 83 cm inseam gives about 55, which points at a 55 or a 57. Treat it as a cross check on the table above. For the underlying measurements, see our guide on how to measure a bike frame.
Revelator Alto (race flagship)
The Alto has been KTM's road race bike since 2018 and is now in its third generation. KTM developed it with its professional teams and tuned the tube shapes in the wind tunnel, with the stated aim of keeping climbing performance while lowering drag. It comes in five sizes, 49 to 59, and it is the low end of the KTM road range. The 2027 Pro build ships on 30 mm tyres.
| Size | Stack (mm) | Reach (mm) | Rider height |
|---|---|---|---|
| 49 (XS) | 519 | 361 | 150 to 164 cm |
| 52 (S) | 535 | 377 | 165 to 169 cm |
| 55 (M) | 550 | 387 | 170 to 179 cm |
| 57 (L) | 559 | 392 | 180 to 187 cm |
| 59 (XL) | 571 | 396 | 187 to 194 cm |
Geometry is 2027 model year data from ktm-bikes.at. We also read the 2026 Alto Pro page and the figures match to within rounding, so a 2026 bike fits the same as a 2027 one.
Fit character: low and long, with a short head tube and a marked saddle to bar drop.
Revelator Syro (endurance)
The Syro is the newer carbon platform, and KTM describes it as a comfort oriented geometry with a slightly more upright riding position. It carries seven sizes, 46 to 61, which is the finest size grid in the KTM road range. The 2027 Comp build ships on 32 mm tyres. Chainstays are 415 mm, against 410 mm on the Alto.
| Size | Stack (mm) | Reach (mm) | Rider height |
|---|---|---|---|
| 46 | 513 | 363 | not published |
| 49 | 534 | 367 | 150 to 164 cm |
| 52 | 554 | 376 | 165 to 169 cm |
| 55 | 573 | 380 | 170 to 179 cm |
| 57 | 590 | 385 | 180 to 187 cm |
| 59 | 607 | 389 | 187 to 194 cm |
| 61 | 626 | 392 | not published |
At size 55 the Syro is 23 mm taller and 7 mm shorter in reach than the Alto. That is roughly two stacked spacers plus a shorter stem, handed to you by the frame.
Fit character: taller and slightly shorter, an endurance position that still holds a decent turn of speed.
Revelator 10 and Revelator 15 (alloy)
The alloy Revelator arrived in the range for 2026 as the entry point, with a carbon fork and hidden welds. The 10 and the 15 share one frame and one geometry chart, in five sizes from 49 to 59. Chainstays are 420 mm, the longest of the three platforms, which is part of why it feels steadier than the Alto.
| Size | Stack (mm) | Reach (mm) | Rider height |
|---|---|---|---|
| 49 (XS) | 532 | 363 | 150 to 164 cm |
| 52 (S) | 550 | 372 | 165 to 169 cm |
| 55 (M) | 564 | 383 | 170 to 179 cm |
| 57 (L) | 573 | 388 | 180 to 187 cm |
| 59 (XL) | 581 | 393 | 187 to 194 cm |
Fit character: a middle ground, taller than the Alto and shorter than the Syro at the same number.
What riders say about KTM road sizing
Published feedback on KTM road fit is mostly German language and mostly about the Alto. Two points come up repeatedly.
- The Alto position is genuinely low. In its November 2022 test of the Alto Master, radsport-rennrad.de put the riding position down as sporty and clearly stretched, pointing at the marked saddle to bar drop and the comparatively long reach. Its June 2024 test of the Alto Exonic reached the same conclusion, describing the position as low and stretched.
- Comfort was not the design brief. The same June 2024 test noted that ride comfort is not among the Alto's strengths, with the low set seat stays and the tyres doing most of the damping work. If you want an endurance position from KTM, the Syro is the frame, not a taller stem on an Alto.
One practical note on pre-owned bikes. Older Revelator and Revelator Lisse frames still turn up on the used market, and KTM's site lists geometry only for the models currently in the range. For those, ask the seller for the measured stack, reach and seat tube length rather than working from the size label.
Between two sizes?
Choose the smaller size for a lower, sharper front end and quicker handling, and the larger one for more stability and a longer reach on long days. Two KTM specific points are worth adding.
- On the Alto, reach grows only 4 mm between 57 and 59 while stack grows 12 mm. Tall riders gain height more than length, so a long torso may be better served by a 57 with a longer stem.
- The Syro's seven sizes step by 3 to 9 mm in reach, the finest grid KTM offers on the road. If you sit between two sizes on other brands, the Syro is the KTM most likely to land on your numbers.
KTM fits an internally routed KTM TEAM Road ICR stem across the carbon range. Swapping stem length later means opening the cockpit, so it is worth getting the frame size right at purchase rather than planning to correct it afterwards.
Shop KTM at Bikeroom
- All KTM bikes for the full range, including gravel and mountain bikes
- Road bikes to compare the Revelator against other brands
- Pre-owned road bikes for older Alto generations
If KTM is new to you, our piece on the history of KTM bikes covers where the brand sits. For the other two categories, see the KTM gravel size guide and the KTM mountain bike size guide.
If you are weighing a 55 Alto against a 55 Syro and cannot tell which position you would actually ride, talk to our concierge with your current bike's stack and reach to hand.
Disclaimer: the sizes in this guide are indicative and offered as general guidance, not as a fitting guarantee. Geometry figures are official KTM manufacturer data for the model years named, and KTM can change them between model years. Body height bands come from KTM's own frame sizes chart, which KTM labels a rough indication. Always confirm against the exact bike you are buying and, where possible, with a professional fit.
Sources: KTM Bikes official road range and geometry; KTM Bikes frame sizes chart; radsport-rennrad.de, 2 November 2022; radsport-rennrad.de, 10 June 2024.
