Originally Posted by
Sierra_rider
I do think that bike geometry is a limiting factor to wheel circumference. On my 29"er XC bike, I'm running a slammed -13° stem to get into my preferred position. Unless the saddle and BB got raised a corresponding amount, I can imagine that I'd have to get fairly extreme with my stem choice on a 32" wheeled bike.
As far as wheel diameter, traction isn't the driving issue IMO, rather it's about how well larger wheels roll over rough surfaces...which in some cases, does improve traction. Maybe not such a huge deal on smooth dirt, but 29" wheels are massive improvement for the rocky terrain I ride. I'm not about to trade in my 29"er for a big wheel bike quite yet, but I could imagine there are some benefits to a 32" wheel in certain MTB disciplines...assuming the geometry can be sorted out.
For very lightweight carbon bike wheels, maybe 32", and for rocky racing. For everyday folks, is it worth it over way cheaper wheels? Or at least waiting until wide availability and prices drop. I love that my bikes use tech that is old enough that parts are available generic and cheap. I love my generic design of a 2-piece hollow-spindle crank, but purchased in 2022, with 2X rings and external bearings, was $60 complete.
For other vehicles where the wheels and tires are heavier, once you are large enough diameter to mount the biggest brakes you need, and the tires roll over the obstacles you need them to, they try to get away with the smallest and lightest wheels and tires, and use suspension to suck up the bumps. However, cars, notably, have gotten ever bigger in wheel (rim) diameter, but with the same outside diameter on tires, with ever lower sidewall depth, and when they hit a bad pothole, it often bends the rim. For performance cars, lower profile tires improved handling. For average sedans, it's for looks, at the expense of ride and durability. 29er bike wheels were the opposite, same size (700c) rims, with much cushier tires. My grasp of the 32s is that they are increasing the rim diameter too.
A LBS here has that attitude about carbon fiber; Only use it if you are a bonafide racer. Otherwise, stick to more robust materials with safer failure modes. They have tons of jagged failed carbon to show folks.
Lastly, smaller wheels are stronger, better hoop/arch strength. Those 32 rims will be less resistant to bending inward radially than a smaller diameter, and will not transfer that load to other parts of the wheel as well. However, if they are strong enough to spring back, that might offer a bit more cushion. But it's better that cush be in the tires than the rims. Some vehicles now have flatproof solid rubber tires with wheel spokes in a spiral or S shape, for shock absorption.