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Moab trails?

bajadahl

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So, in terms of simple things to do, assuming Rivian is watching/listening, Bill's recommendation of smaller wheels and bigger tires (more traction) is the first change to make for better off-roading/adventuring. Numbers 2 & 3?
Yes - but unfortunately it's not that simple since smaller wheels almost certainly won't clear the brake calipers.... So the quickest best improvement is better off road tires on the same equipped wheel (I think the smallest is 20") at this point...
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BillArnett

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there are numerous off-roading segments - high desert running, rock climbing, overlanding, glamping, dirt but fairly easily passable roads, like fire roads.... If you were going to rank order Rivian's off-roading capabilities and market segments to serve, what would they be?
I think Rivian will perform best at glamping and least well on rock crawling:

Glamping: sure, you don't need much in the way of off-roading capability but the pretty interior is nice.

Fire roads: OK easy enough but watch out for gremlins that eat sidewalls.

Overlanding: range may be an issue. It would be a real drag to run out of juice 100 miles from the nearest charger. And you can't just carry extra fuel. (Please don't suggest solar panels, an array small enough to be portable just can't provide enough energy to be useful.) Some overlanders get into more difficult trails but aside from that OK.

High speed desert bombing: Rivian looks to be pretty good in this department but I worry about durability. Can it survive hitting a deep pot hole or whoop-tee-doo at 50 mph?

Rock crawling: see my previous comments.

IMHO if you're good at rock crawling then all the other stuff gets way easier. Except for highway. There's no doubt that the big soft tires you want on the rocks just suck big time on the highway. But if I just wanted to drive on the highway I would take my Tesla.
 

aAlpine

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It might be, for instance, that a "software locker" would be a help sometimes. By that I mean having the software insure that all 4 wheels turn at the same rate. Or perhaps the same rate but modified by the steering angle. Not a big deal but it's "only software" :)
I think this is an interesting idea. I'd love for Rivian to talk more about the algorithms behind powering the 4 motors in off road terrain. I've read somewhere that electric motors in EVs are controlled by torque rather than speed (possibly one of those Rimac engineering vids...). This makes it much easier to account for the differing wheel speeds in corners and also torque vectoring. I'm wondering if this is a downside offroad however: in all the videos we've seen so far where the R1T looses traction, the wheel looks to be spinning at high speeds, throwing dust and rocks up into the air. Probably making it harder to stop wheel spin like this is the fixed gearing ratio, and no transfer case like a traditional 4x4.
 

BillArnett

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Yes - but unfortunately it's not that simple since smaller wheels almost certainly won't clear the brake calipers.... So the quickest best improvement is better off road tires on the same equipped wheel (I think the smallest is 20") at this point...
Yeah. But why in the world did they chose to fit such giant brakes? This isn't a race car.
 

BillArnett

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I think this is an interesting idea. I'd love for Rivian to talk more about the algorithms behind powering the 4 motors in off road terrain. I've read somewhere that electric motors in EVs are controlled by torque rather than speed (possibly one of those Rimac engineering vids...). This makes it much easier to account for the differing wheel speeds in corners and also torque vectoring. I'm wondering if this is a downside offroad however: in all the videos we've seen so far where the R1T looses traction, the wheel looks to be spinning at high speeds, throwing dust and rocks up into the air. Probably making it harder to stop wheel spin like this is the fixed gearing ratio, and no transfer case like a traditional 4x4.
Mostly right. Torque and speed are of course related. But I suspect (guess) that it's actually kind of complicated. But it would be easy enough to add wheel speed sensors if the aren't there already. My guess is that the ugly looking wheel spin we've seen in their videos is the result of the traction control operating too slowly. And if that's hard to fix (faster, customized, more expensive computer?) then a "software locker" sounds like an easy fix. But of course I don't really know how hard it would be.

I think gearing is irrelevant. The reason ICE cars have gears (and/or low-range transfer cases) is to multiply the torque. And to be able to get the engine into it's power band at different road speeds. Electric motors have so much torque in the first place and such a nice broad torque curve that gears are not needed. Tesla has demonstrated that very clearly.
 

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BillArnett

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The OP asked about Moab. Yeah, Rivian will be fine on the easy ones like White Rim, White Wash Dunes, the Tower Arch road, and the Shaefer Trail (and probably a few more boring ones I can't remember). It might manage Top of the World with considerable caution. Maybe Rose Garden Hill with extreme caution. Hell's Revenge, Fins n Things: maybe if you can get up onto the fins without damaging the bumpers. Elephant Hill: maybe but that narrow spot (Devil's Pocket?) might eat the paint. Moab Rim, Poision Spider Mesa, Cliff Hanger, Golden Spike: forget it, the approach/departure angles are too steep. Behind the Rocks, Pritchett Canyon: don't even think about it.
 

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Yeah. But why in the world did they chose to fit such giant brakes? This isn't a race car.
I agree that brakes that would fit inside an 18" wheel probably would have been sufficient. Remember though that Rivian is all about performance on the road too & that these are heavy vehicles for their size.

From a safety perspective, it's definitely not a bad thing to have bigger brakes for relatively heavy vehicles. Disk radius/diameter is the only braking variable with an exponential effect.

With that said, the brakes on my HD 2500 truck fit inside 17" wheels & stop the almost 7K lb truck extremely well, even towing loads without trailer brakes.
 

BillArnett

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I agree that brakes that would fit inside an 18" wheel probably would have been sufficient. Remember though that Rivian is all about performance on the road too & that these are heavy vehicles for their size.

From a safety perspective, it's definitely not a bad thing to have bigger brakes for relatively heavy vehicles. Disk radius/diameter is the only braking variable with an exponential effect.

With that said, the brakes on my HD 2500 truck fit inside 17" wheels & stop the almost 7K lb truck extremely well, even towing loads without trailer brakes.
Right. And your big truck doesn't have regen braking to supplement the friction brakes.

I'll go out on a limb here and assert that big brakes are not really a safety thing but more of a marketing ploy. I'm not an automotive engineer. But I do know some basic physics. And I know that basic physics isn't the whole story. Nevertheless...

The retarding force applied by the brakes is limited by the traction between the tires and the surface. It's actually pretty easy to make brakes that can apply more force than the tires can handle even with good traction. Big brakes are completely irrelevant on the dirt where traction is poor. But there's another issue: heat. All the kinetic energy of the car is converted to heat by the friction in the brakes. Thus the brakes get hot. And if they get too hot they stop working and you die. So the brakes have to dissipate that heat. This is no big deal from a safety point of view; one panic stop from freeway speed won't heat the brakes enough to matter. But racing is a whole different story because the brakes are used repeatedly in a short period of time. Thus they have to dissipate the heat more rapidly. Hence they need to be bigger (more metal to heat up in the first place, more area to radiate it from; drilled/slotted rotors and air flow specifically directed to the brakes also helps). So race cars have big brakes and street racing wannabes think big brakes make their cars look racy and cool. And red calipers are cooler yet. And yellow ones are even better :)

Frequent, repeated heavy braking is just not an issue in normal driving. Even if you're towing a heavy trailer or carrying a heavy load downhill you should use engine braking to ameliorate dissipate most of the heat. And an electric vehicle does one better putting the energy back into the battery. If it were allowed by the regulators EVs could probably get away with no brakes at all. (Though they might need an emergency way to dump energy when the battery can't take it, an unusual situation.)

So I think Rivian is compromising off-road performance in favor of the street racing crowd.
 

BillArnett

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So, in terms of simple things to do, assuming Rivian is watching/listening, Bill's recommendation of smaller wheels and bigger tires (more traction) is the first change to make for better off-roading/adventuring. Numbers 2 & 3?
#2 would be better approach and departure angles. This might be as easy as removing the plastic bits below the bumpers (which are no doubt there for aerodynamic reasons, irrelevant off-road). Or it might necessitate a whole bumper redesign.

#3 would be armor under the bumpers and especially under the rocker panels (below the doors). These areas take a beating. Plastic won't handle it.

#4 would be a max ride height setting. If I'm recalling correctly, I was told the the max height of the suspension is software limited to several inches less than the actual suspension travel. This is to prevent damage to the U-joints by applying too much power thru a big angle. But it would be just fine if a max height setting severely limited the power. This max setting would be used only for getting off a high-centered situation or climbing a ledge. Obviously this would go a long way toward #2 as well.

Oh, I forgot #0: gotta have a way to attach and power a winch. (Ideally it would be just a clutch and some gears on one or more of the motors but that's probably too hard.) Just provide a strong point with the Warn standard bolt pattern and a way to get 500 amps at 12 volts.
 

Coast2Coast

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I read or heard somewhere that steel bumpers, as opposed to standard plastic, would be an option, but I know nothing more than that. (I probably heard it at the Mill Valley/SF event, the only Rivian event that I attended.)
 

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BillArnett

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Yeah, at that same event I was promised that there would be a winch option, too. I hope that's right. As for the bumpers, the way I interpreted what was said is that there will be some sort of skid plate under the bumper(s). That's all well and good but insufficient if the corners remain plastic.
 

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I still think these vehicles will do 98% of what people need or want them to do.

I still hold out hope for a Wrangler or Bronco competitor from Rivian (or Rivian skateboard underpinning a Bronco EV), a "streetable" but more purpose built offroader. I'd be an immediate reservation holder.
 

BillArnett

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I still think these vehicles will do 98% of what people need or want them to do.

I still hold out hope for a Wrangler or Bronco competitor from Rivian (or Rivian skateboard underpinning a Bronco EV), a "streetable" but more purpose built offroader. I'd be an immediate reservation holder.
Agreed. 99.9% (guesstimate) of people who buy Wrangler Rubicons never drive the Rubicon Trail. 98% of them never do anything off-road harder than a fire road. Ditto for buyers of Range Rovers and MBZ G-Classes.

My point is that if Rivian could really handle that tough stuff then it would be so much easier and less stressful to deal with the easy stuff. And the marketing could honestly say "you can have it all".
 

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ah, skyote, always the voice of reason, and that's a good thing. If you can serve 98% of the market, you're doing great.

Under Alfred Sloan at GM, the goal with multiple models - Chevrolet, Pontiac, Oldsmobile, Buick and Cadillac, a model for every income bracket - was to capture 80% of the market. GM never got there, but it did capture 60% at its high point.

So, if Rivian can capture 98% of the adventure market, it's doing wonderfully well.
 

azbill

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While they were in Arizona, maybe still here, they should have done the backway to Crown King.

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