First time off-road in my R1T, Question about descending

[JeffC]

After six months of ownership, I finally had an opportunity to get my truck off-road this weekend. I was mountain biking in Bear Valley, CA and used the truck to shuttle to the top of a decent. It involved climbing a fairly gnarly jeep road. Lots of medium sized boulders, deep ruts, and loose rock. Pitch and roll both maxed out at 15%. I followed a jacked up wrangler up the hill and had no trouble keeping up. This was my first experience with any vehicle on a road like this and the Rivian made it very easy.

My only minor issue was controlling the truck on the descent. I was in standard off-road mode and had regen on high but the truck would often not slow at all without using the brakes. I noticed that over a certain pitch the rear wheels did not regen - only the front. Without the brakes the truck was rolling much faster than was comfortable. Is there some other setting that I could have used to help control that?

I'm looking forward to more excursions like this and would appreciate any advice folks could share.

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[UnsungZero_OldTimeAdMan]

After six months of ownership, I finally had an opportunity to get my truck off-road this weekend. I was mountain biking in Bear Valley, CA and used the truck to shuttle to the top of a decent. It involved climbing a fairly gnarly jeep road. Lots of medium sized boulders, deep ruts, and loose rock. Pitch and roll both maxed out at 15%. I followed a jacked up wrangler up the hill and had no trouble keeping up. This was my first experience with any vehicle on a road like this and the Rivian made it very easy.

My only minor issue was controlling the truck on the descent. I was in standard off-road mode and had regen on high but the truck would often not slow at all without using the brakes. I noticed that over a certain pitch the rear wheels did not regen - only the front. Without the brakes the truck was rolling much faster than was comfortable. Is there some other setting that I could have used to help control that?

I'm looking forward to more excursions like this and would appreciate any advice folks could share.

Use the brakes. It's why the truck still has them... and there's nothing wrong with yours. Even on pavement, there are situations where regen alone is not enough for a 7,000+ lb vehicle in motion, under effects of gravity and with varying amount of available traction between tires and ground surface. And regardless of powertrain/drivetrain and vehicle type, most of the braking is done at the front axle (because of weight transfer, to the front, under deceleration). The rears are mostly along for the ride and used to help control direction of travel (yaw). This is also why front brakes are larger than the rears in almost all cars.

 

[DeanB1452]

Hey Jeff! The Bay Area Rivian Club and Sierra Nevada Rivian Club has some off-roading excursions that might interest you. Check out BARC's site here: Bay Area Rivian Club – An Official Chapter of Rivian Clubs of America or join on Heylo here: https://heylo.group/bayarearivianclub
CJ Arneson, president of BARC Chapter, also teaches off-roading courses. Check out his site here: Off-Road Training Courses in California & Nevada | Sierra Nevada Off Road Academy

 

[valkyrie]

I was just up in Lake Alpine right down the road from Bear Valley this weekend. I’ve only taken my Land Rover on those trails! Nice work!!

Did you try rock crawl with hold on during your decent?

PS- Did the Arnold Tesla SC work for you? My truck would not handshake. I even drove out to cell coverage and initiated a charge directly from the Tesla app. Never had that problem before but had to drive all the way back to Copperopolis to charge there which kind of sucked.

 

[MountainBikeDude]

I'm fresh off some off-road adventures myself. Congrats on the off-road baptism

On braking, I was super stubborn about not enabling regenerative braking assist. I preferred knowing when my regen was limited and stayed within its braking force, by limiting my speed accordingly on descents. But on a 7 hour FSR exploration/rally mode rip, I wanted simplicity, so I enabled it. If you're looking for consistency over long descents, braking assist is the way to go. As regen starts to become limited, the brakes will start to supplement the braking force for a more predictable drive.

Some photos of the day.
The elevations in the graph are in meters. The section of FSR was between markers 9 and 11. Roughly 200kms of FSR's with several branches forking up into some of the surrounding mountains. The entire loop, Vancouver through Whistler, Pemberton, then along two lakes was about 480kms. Average efficiency was 3.2km/kWh (2mi/kWh) 4200m elevation gain, 4400m descent.

 

[VandalSibs]

Average efficiency was 3.2km/kWh (2mi/kWh) 4200m elevation gain, 4400m descent.

I must not have had enough tea this morning, because thanks to the kilometers you mention in the sentence before this, I thought it said that you gained and dropped 4,200 & 4,400 km. I was wondering if you had somehow gotten your truck to Mars and were going down Olympus Mons....

 

[Owner]

My only minor issue was controlling the truck on the descent. I was in standard off-road mode and had regen on high but the truck would often not slow at all without using the brakes.

I'm curious why you didn't try another mode. When I did a gnarly albeit short decent I had no trouble keeping the R1S going very slow with high regen (my default) in rock crawl by just the smallest control of the brake pedal where necessary.

 

[JeffC]

I'm curious why you didn't try another mode. When I did a gnarly albeit short decent I had no trouble keeping the R1S going very slow with high regen (my default) in rock crawl by just the smallest control of the brake pedal where necessary.

Thanks for all of your feedback

I failed to mention one important detail; I have a dual motor, not a quad. My options are the general purpose off-road mode, sand, or rally. I didn't try either of those. I guess I should have at least tested them but the names didn't sound like they would be better (understanding if this was correct is the intention of my original post).

As for the brakes, I did resort to using them and it did help but I was confused by the truck's behavior because in San Francisco the truck will completely stop itself from 20 mph while descending a 28% (16 degree) grade and hold the truck still after stopping. I don't understand why the truck would free roll after stopping off-road while still on high regen on a lesser grade and why sometimes the rear regen was on and sometimes off.

@valkyrie
I did charge in Arnold - good thing it worked for me because I didn't have enough juice to make it to Copperopolis. I used the Tesla app to connect with no trouble. While I was there another R1T owner mentioned similar problems to yours (perhaps that was you?)

 

[Owner]

Thanks for all of your feedback

I failed to mention one important detail; I have a dual motor, not a quad. My options are the general purpose off-road mode, sand, or rally. I didn't try either of those. I guess I should have at least tested them but the names didn't sound like they would be better (understanding if this was correct is the intention of my original post).

Ah, yes I doubt sand or rally would have helped as I think those are tuned for higher speeds. I'm by no means an expert at this and I do have a TRI but an R1S.

 

[UnsungZero_OldTimeAdMan]

Thanks for all of your feedback

I failed to mention one important detail; I have a dual motor, not a quad. My options are the general purpose off-road mode, sand, or rally. I didn't try either of those. I guess I should have at least tested them but the names didn't sound like they would be better (understanding if this was correct is the intention of my original post).

As for the brakes, I did resort to using them and it did help but I was confused by the truck's behavior because in San Francisco the truck will completely stop itself from 20 mph while descending a 28% (16 degree) grade and hold the truck still after stopping. I don't understand why the truck would free roll after stopping off-road while still on high regen on a lesser grade and why sometimes the rear regen was on and sometimes off.

@valkyrie
I did charge in Arnold - good thing it worked for me because I didn't have enough juice to make it to Copperopolis. I used the Tesla app to connect with no trouble. While I was there another R1T owner mentioned similar problems to yours (perhaps that was you?)

Maybe temp of motors and or pack caused regen to be trimmed back. Is brake assist enabled?

 

[SwampNut]

You were losing traction on the rear. I have a quad and have watched it control tire slip individually. I also did an off-roading trip with the head of off-road engineering for Rivian, and we talked about this. When facing downhill, the truck's weight and traction is transferred to the front, and the rear loses traction easily. You don't want to have tires sliding, which can be a disaster.

Did you air down? I run 24 PSI off road and that helps a lot (20" AT tires).

https://www.rivianforums.com/forum/threads/off-road-trip-with-some-rivian-engineers.48080

 

[valkyrie]

@valkyrie
I did charge in Arnold - good thing it worked for me because I didn't have enough juice to make it to Copperopolis. I used the Tesla app to connect with no trouble. While I was there another R1T owner mentioned similar problems to yours (perhaps that was you?)
[/QUOTE]

That wasn’t me but that is useful information thanks for sharing! I had zero cell connectivity on AT&T, so had to drive out a mile to initiate the session from the app after plug and charge failed. Only thing I noticed different from everyone else charging successfully was I had a Rivian and an adapter. Roadside assistance did mention the truck has a failsafe if there are to many consecutive failures to initiate a charge. It is at the SC now trying to figure out why highway assist stopped working so I asked them to also pull any diagnostics they could from the failed charge session.

 

[MountainBikeDude]

I must not have had enough tea this morning, because thanks to the kilometers you mention in the sentence before this, I thought it said that you gained and dropped 4,200 & 4,400 km. I was wondering if you had somehow gotten your truck to Mars and were going down Olympus Mons....

Funny you say that...

 

[JeffC]

@valkyrie

I had zero cell connectivity on AT&T, so had to drive out a mile to initiate the session from the app after plug and charge failed. Only thing I noticed different from everyone else charging successfully was I had a Rivian and an adapter.

Rivian's internet connection is also through AT&T. Perhaps it needs to communicate with Tesla to initiate the charging session but could not do that without a cell signal?

 

[usulio]

It's good to use the friction brakes on an off-road descent. If you are using strong regen braking and a wheel loses traction, it will actually spin backwards and make things worse. I bet Rivian decreases regen power in off-road mode on purpose.

If you're pointing down a steep hill, all the weight is on the front wheels so rear wheel braking is not going to be as effective.

What I like to do is try to two-foot drive. When I need more braking, I use my left foot on the friction brake. Keep my right foot on the right pedal the whole time.

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