[Hardrake]

If you compare the contact patch of a Derby 34mm internal rim wheel/tire combo Vs. a generic 29er wheel/tire combo with a 23mm internal rim; which one has the biggest contact patch on the ground?

I know that many variables go into properly calculating the answer to this question (tire size, tread qualities, etc.) but forget all that for a moment. I'm just looking for a very general comparison between the contact patch of a wide Derby 27.5 wheel and that of a generic 29er, assuming the measurements I stated in the first paragraph.

Also, which of those 2 combinations would offer greater/more efficient climbing power up steep rocky/rooty/loose rocks/ like trails?

Can someone list the pros/cons of these 2 types of wheels in regards to all the different types of riding environments....

Thanks!

 

[Salespunk]

The advantage of Derby over a standard wheel is the ability to run lower pressure. This will provide greater traction in almost every situation. Contact patch grows even more because the tire will deform more as well.

 

[Iceman69]

The advantage of Derby over a standard wheel is the ability to run lower pressure. This will provide greater traction in almost every situation. Contact patch grows even more because the tire will deform more as well.

Probably not the best advice to run low pressures on a carbon wheel. If you ride trails with rocks that is.

 

[Salespunk]

Probably not the best advice to run low pressures on a carbon wheel. If you ride trails with rocks that is.

I ride a lot of rocks at high speed without issue unless I run stupid low like 14 F or 20 R. My normal pressure is 16.5 F and 25 R.

 

[Iceman69]

16.5 psi? Man I need to go digital on the pressure gauge.
What's your weight rtr? Do you ride drops to flat etc...
I weigh 150 ish rtr and run about 17 front and 20 rear which is risky if I'm riding aggressive trails. 20 psi rear feels overinflated at least for my weight.

 

[Hardrake]

I'm not worried about rim strikes harming my Derby rims. If the impact tests they did and show on their website is true, it should be a non-issue for me.

Here is the impact test:

AM Spoke pull force test: 352KgF (775 lbs, spoke broke, no rim damage)
AM Rim impact force test: 267KgF (588 lbs, cracks at valve hole, 90’ from force)

These numbers show the brute strength of these wheels and I'm impressed. I weigh 170-175 pounds and I don't do drops or jumps. Even if I were to land a 15-25 foot drop on rocks or pavement, there is no way I would exert 588 lbs. of pressure on the bike. With Derby wheels, you're biggest concern will be lowering the air pressure too much; resulting in tire damage, which may require you needing to buy a new tire.

If my statement is not true, I'd be interested to get an explanation as to why...