34T or 36t Front Chain Ring

[Singletrackmind]

Do most emtb's come with a 34t or 36t front chain room?

What are benefits of each?

 

[Greg Watts]

Do most emtb's come with a 34t or 36t front chain room? What are benefits of each?

Most eMTBs ship with a 34T chainring as standard. It's the safe, do-everything choice that motor manufacturers have settled on, and it works well for the majority of riders. That said, a 36T swap is one of the most common upgrades in the eMTB world, and for good reason.

The 34T gives you a slightly lower gear range, which means easier spinning in the lowest gears on steep climbs. On a full-power motor like your Bosch Gen 5, that advantage is fairly marginal since the motor is doing the heavy lifting anyway, but it's there. The other practical benefit is that a 34T ring tucks in closer to the motor housing. @Suns_PSD noted that full power motors extend below the 34T ring, providing natural chainring protection, and with the Bosch Gen 4 cover the protection is roughly 95% of the ring. Useful if you're bashing through rocky terrain, though San Diego's trails are generally kinder in that regard.

The 36T, on the other hand, gives you a taller top gear for higher speed pedalling and, crucially, better use of your cassette range. With a 34T you tend to live in the middle of the cassette, which means you're wearing the same few sprockets disproportionately. @James_C found that running a 36T spreads the load across the cassette and noticeably reduces chain wear, which is worth thinking about given what SRAM AXS chains cost. @Zimmerframe also pointed out the 36T lets you pedal comfortably past 50kph without the hamster wheel sensation, which matters if you're doing any fire road descents or linking trail segments at speed.

The main thing to watch is chainstay clearance. On some frames a 36T is a tight fit, and on a few (like the Trek Rail XL) it simply doesn't work. Your Orbea Wild should be fine with a 36T, but it's worth checking clearance before committing, and if you're running a chain guide, that may need repositioning. You'll also want to add a couple of chain links when you go up in size.

Given your setup with the SRAM AXS Transmission and Bosch Gen 5, a 36T is probably the better choice for your riding. You're not scrambling up Lake District gradients in San Diego, so you won't miss the lowest gear, and the improved chain life and cassette spread are tangible benefits. I've also got data on specific chainring brands, alloy versus steel longevity, and chain guide compatibility if you want to dig deeper.