Pinion MGU: Chain vs belt drive comparison and brand choices

[urmom]

E.g. with Pinion MGU, you have the option bikes with a special sturdy chain or a belt.
Both are used in popular bikes (e.g. Bulls vs Rotwild).
What are advantages and disadvantages?
Why did Rotwild go chain and Bulls go belt?

 

[Greg Watts]

E.g. with Pinion MGU, you have the option bikes with a special sturdy chain or a belt. Both are used in popular bikes (e.g. Bulls vs Rotwild). What are advantages and disadvantages? Why did Rotwild go chain and Bulls go belt?

You've already clocked the two big ones yourself - the belt feels slightly spongier and needs less looking after - so here's the fuller picture.

Belt (Gates CDX - what Bulls runs on the Vuca EVO):
• Genuinely low upkeep: no lubrication needed, dirt and mud just rinse off with water, no rust, and service life can exceed a chain-and-sprocket setup many times over.

• But it's not zero-maintenance: in dust it needs washing or it creaks, and in heavy mud, build-up on the wide cogs and belt can eventually throw the belt.

• Repairability is the weak spot: if it snaps, fitting a new one is more involved than a chain, and the spring tensioner sits in a vulnerable spot beneath the front pulley - often first thing to hit when the bike bottoms out. A belt can't be split like a chain either, so the frame needs an opening in the rear triangle to install it - on the Nicolai S16 MGU you open the drive-side pivot. That constrains frame design.

• The "spongy" pickup you noticed is real but harmless - it's the belt pulling tight on the cogs under tension rather than actual stretch.

Chain (Rotwild's choice):
• Cost and ease of repair/replacement - the big single-speed e-bike chains are so burly some owners barely lube them. Quick-link fix on the trail, tolerant of mud, and the tensioner is tidier: with a chain, the chunky spring tensioner under the bottom bracket is replaced by a smaller, more discreet tensioner at the rear.

• Downsides: you're back to lube, wear and noise. Reviewers found the R.X1000 a loud companion, with the chain slapping against the frame - belt MGU bikes are near-silent downhill.

Why each brand chose what they chose: Rotwild have said it themselves - "especially from the point of view of sportiness and our ROTWILD tradition, we rely on a long-life chain", citing roughly 98% efficiency and low maintenance because it runs dead straight with the MGU, without derailleur skew. Bulls went the other way for the full carefree package - their Vuca EVO AM pairs the MGU with a Gates CDX belt as the whole point of the bike: one drivetrain you basically never touch beyond the 10,000km gearbox oil change.

Short version: belt if you want minimum faff and don't live in a bog; chain if you want cheap parts, trailside fixes and a marginally more direct feel - at the price of lube duty and some slap. Efficiency-wise it's a wash: testing found the MGU with belt showed no weakness versus other motors with a chain drive, so I wouldn't pick on that basis.