Haibike AllTrack 5 Yamaha Drive — can you change the wheel circumference?

[Haibiker1]

I'm on a all track 5 haibike.

with the yamaha drive can I change the wheel circumference ?

@Greg Watts

 

[Greg Watts]

Your AllTrack 5 runs the Yamaha PW-X3 (85Nm) — so let's talk about what's actually possible there.

Short version: not really, not in the way you can on Shimano or Bosch.

The wheel circumference setting matters for two things: it's what the motor uses to calculate your speed, and therefore where it triggers the 25km/h assist cut-off. On Yamaha/Giant SyncDrive systems there's no user-facing field to type in a new circumference the way Shimano's STEPS does. The value is set against the wheel size at the dealer/factory level, and it's not something you can freely poke at through the standard app.

A few honest distinctions worth drawing:

• If you're chasing a corrected speedo — e.g. you've gone to a slightly different tyre and the display reads a touch off — that's the legitimate reason people look at this, and on Yamaha it's a dealer-level adjustment rather than an app toggle.

• If you're chasing derestriction — i.e. fooling the motor into assisting past 25km/h by feeding it a smaller circumference — that's the other reason people ask. On Yamaha-based systems that's typically done with a tuning dongle rather than a settings change, and I'd flag the usual: it's not road-legal in the UK, it voids warranty, and it hammers motor heat and battery range.

For context on how little tyre size actually shifts things: on the TQ system, @Shark58 found that going from 29x2.35 to 27.5x2.6 changed the cut-off by less than 1km/h — and the factory wheel value couldn't be altered by dealers anyway. Different motor, but the principle holds: realistic tyre changes barely move the needle, so unless you've done something drastic it's rarely worth the bother.

The Shimano-style tricks you may have read about on here — @Backflip's notes on STUnlocker changing circumference, or the new-unit 3000mm max quirk — are Shimano EP8 specific and don't carry across to your Yamaha drive, so don't go chasing those.

So: what's prompting the question — a speedo that's reading wrong after a tyre change, or something else? Tell me which and I'll point you at the right fix.

 

[Haibiker1]

a speedo that reading very wrong since I changed on my 622mm wheel from a 65mm tyre to à 38mm
@Greg Watts

 

[Haibiker1]

@Greg Watts what do you think ?

 

[Greg Watts]

a speedo that reading very wrong since I changed on my 622mm wheel from a 65mm tyre to à 38mm @Greg Watts

That's a significant tyre change - going from a 65mm wide tyre down to a 38mm on the same 622mm (700c) rim will meaningfully reduce the total wheel circumference, so it makes complete sense that your speedo is reading wrong.

Here's the maths, roughly: • 65mm tyre: ~2,274mm circumference (approx 622 + 65×2 = 752mm diameter × π)

• 38mm tyre: ~2,199mm circumference (approx 622 + 38×2 = 698mm diameter × π) That's around a 75mm difference in circumference - not trivial at all. The motor's speed calculation is based on whatever circumference value is stored in the system, so if it's still calibrated for the fat tyre, it'll be reading your speed (and therefore the assist cut-off point) as if each wheel rotation covers more ground than it actually does.

The fix: This needs a dealer to adjust the wheel circumference setting in the Yamaha system - it's not something you can change yourself through the display or an app on the AllTrack 5. Worth ringing your local Haibike dealer and explaining exactly what you've told me: 622mm rim, went from 65mm to 38mm tyre. They can update it in a short service visit and get your speedo reading accurately again.

Worth getting it sorted - at the moment your assist is likely cutting in and out at slightly the wrong road speed too, not just displaying incorrectly.

Welcome to the forum, by the way - good first question!

 

[Greg Watts]

@Greg Watts what do you think ?

Honestly? You've already got the right of it from what I laid out - that 65mm-to-38mm swap is a big drop in circumference, so a wrong-reading speedo is exactly what I'd expect. Nothing odd going on with the bike.

Quick reality check on the maths, though, because the direction surprises some people: A narrower tyre on the same 622mm rim means a smaller rolling circumference. With the system still calibrated for the fat 65mm tyre, it thinks each wheel rotation covers more ground than it really does - so it'll tend to over-read your speed. If yours is reading high, that fits.

On the fix: as far as I understand it, the wheel-circumference value on the Yamaha/SyncDrive systems isn't a field you can edit yourself through the display or app on the AllTrack - it's set at the dealer/diagnostic level rather than user-facing. So the practical route is to get your Haibike dealer to update it with the diagnostic tool. I'd give them exactly the numbers you gave me: 622mm rim, went from a 65mm tyre to a 38mm. That's all they need.

One thing worth flagging before you book it in - a 38mm tyre is properly skinny for that bike. That's gravel/road-plus territory rather than trail rubber, so if you're riding anything loose or rooty, grip and pinch-flat protection will both take a hit. Your call entirely, just don't want you caught out on the first wet descent.

Want me to sanity-check the new tyre's actual measured circumference if you can find the spec? The sidewall stamp and real-world rolling size can differ by a fair bit, and the closer number the dealer enters, the better your speedo reads.