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AskAuthor Ultrasonic 27.5 2025 (matte black/red)
Wheel diameter 27.5"
□ Suitable for heights of 140–170 cm, frame sizes 14"/16"
□ Weight 11.5 kg
□ New hydroformed aluminium frame, 32-tooth single chainring, shorter 165/170 mm cranks
□ RST air fork, TEKTRO hydraulic disc brakes
□ CST B-Trail Kevlar tyres 27.5" × 2.25"
□ SHIMANO CUES components, 11-speed
Do you have an ambitious young rider at home who is slowly growing up but not yet ready for an adult bike? Then choose the best from our range – the Author Ultrasonic 27.5, designed (not only) for juniors used to winning on race courses. This lightweight special is one of the most popular bikes among young racers. It comes in two frame sizes and is designed for children aged 10–15 and 140–170 cm tall. A superlight 3× butted duralumin frame, a top-class RST air fork, hydraulic disc brakes, sporty geometry, internal routing of hoses and cables, a 1×11 drivetrain – these are all attributes of top racing equipment that loves speed and maximum effort. Light folding Kevlar CST tyres with a fine tread wont slow you down either. Just saddle up and head for the race course or a sporty ride. Another advantage is that it can also serve a petite adult woman who will appreciate its attractive weight and lowered frame.
Frame geometry
| Size | min height | max height | S/T c-t | S/T c-c | T/T h | T/T a | H/Tt | C/S | W/B | S/T ang. | H/T ang. | F/L | B/B | reach | stack | F/R | hb | stem | crank |
| 14" | 140 | 158 | 356 | 550 | 544 | 110 | 420 | 1052 | 74 | 69 | 475 | 45 | 385 | 575 | 43 | ||||
| 16" | 155 | 170 | 406 | 575 | 557 | 115 | 420 | 1067 | 73.5 | 69.5 | 475 | 45 | 403 | 582 | 43 |
Additional information
 |  |  |
| frame: | triple butted hydroformní dural 6061 27.5 |
| pedals: | plast |
| front wheel / hub: | AUTHOR Xenon, 32 děr / AUTHOR Xenon TRC 27.5, 32 děr |
| rear wheel / hub: | AUTHOR Xenon, 32 děr / AUTHOR Xenon TRC 27.5, 32 děr |
| tires: | CST B-Trail, skládací, 27.5x2.25 |
| rear derailleur: | SHIMANO Cues 6000 |
| saddle: | AUTHOR Champion / 14 AUTHOR Navigator / 16 |
| chain: | KMC XGlide |
| fork: | RST F1RST 27.5, vzduchová, uzamykatelná (80 mm) |
| brake levers: | TEKTRO HD-M530 |
| brakes: | TEKTRO HD-M530, kotoučové hydraulické (6″ kotouče) |
| shifters: | SHIMANO Cues 6000 (11) |
| cranks: | PROWHEEL, 32 zubů, 165 / 170 mm kliky / PROWHEEL, BB unit |
| cassette: | SHIMANO CS-LG400-11, 11-50 (11) |
| EAN: | 8590816087569, 8590816087576 |
| seatpost: | AUTHOR dural (31.6) |
| model year: | 2025 |
