Home › Display settings › Specialized Turbo (TCU, TCD, Mastermind TCU/TCD) + Mission Control / Specialized app › Specialized Turbo: wheel size (dealer only)
Wheel circumference on a Specialized Turbo (TCU, TCD, Mastermind)
Wheel circumference is set at the factory and changed only with the Specialized dealer tool. Neither the display nor the Mission Control / Specialized app offers it.
Step by step
- Compare display speed with GPS on a flat kilometre.
- Measure the rolling circumference under load in mm.
- Book a Specialized dealer; they update it with the diagnostic tool in a few minutes.
- Verify against GPS afterwards.
Tip: Mullet conversions on Levo/Kenevo: the sensor is on the rear wheel, so the value must match the rear tyre.
Can't find it?
Dealer says not possible: some model years restrict circumference to a small approved range; outside it the tool refuses.
Frequently asked
Why is it dealer only?
It sets where the assist cut-off happens, treated as a type-approval parameter.
My speed is off after new tyres, is the speed sensor broken?
Almost always circumference, or the rotor magnet gap. Check the gap first.
Does the app show wheel size?
No.
Manuals and video
Other Specialized Turbo (TCU, TCD, Mastermind TCU/TCD) + Mission Control / Specialized app guides
Specialized Turbo: switch mph to km/hSpecialized Turbo: reset trip distanceSpecialized Mission Control: tune assist (Support / Peak Power)Specialized Turbo: System LockSpecialized Turbo: pair with Mission Control / Specialized appSpecialized Turbo: firmware update (app vs dealer)Specialized Turbo: walk assistSpecialized Turbo: lights on/off
Still stuck? Take a photo of the display and show it to a local e-bike workshop. Bring the bike's system name (e.g. Bosch Performance Line CX) and the exact code; that saves diagnostic time and money.