Two seats on a mountain bike

[speedyebikenoob]

I'm expecting to get flamed a little for asking this question, but I'd rather be safe than sorry. I want to add something like this to my e mtb: https://www.thebikeseat.com/

Can someone tell me how dangerous this would be with two people at elevated speeds? I understand that the bike will take longer to brake, accelerate, and turn, but how likely is the failure of the rear wheel or axle or something because of the extra weight at the back? Say both me and my passenger weigh 150 lbs, or 68 kg each.

I like to cruise around 30 mph (50 kph) on my e bike when I'm alone, sometimes a little more. Is it a bad idea to cruise that fast with two people?

 

[99t4]

I can think of at least 4 things that only you can answer to help you answer your question:

1. Passenger: do they know how to lean, unweight, etc. at the appropriate times and not fight your necessary weighting/unweighting manouvers?

2. Terrain: Rough, smooth, slick, challenging traffic, potholes, surprise debris?

3. Rear wheel build quality. Rim quality, spoke quality, quality of assembly?

4. What happens when stopped, can passenger's feet reach the ground?

If this is a priority for you, why not get a utility bike or xtracycle type built for carrying a passenger or two?

Remembering the time my 11-year old biker self was being all studly and giving a ride to my 10-year old girlfriend sitting on the back of my seat stingray. Riding down the sidewalk with a HIGH curb. Struggling as hard as I could, I was.....not.....able.....to.....keep.....the ..... bike .....from.....going .....over..... the..... high.....curb.
She was leaning the wrong way. Somehow my bare foot got caught sandwiched between the pedal and the high curb as we went over and it tore my big toenail right off. Of course I was manly enough that we didn't crash crash but I quickly dropped her off at her place and our date ended prematurely. Then I went home across the alley to continue bleeding in earnest.

 

[Chalo]

Even if the bike is sturdy enough, that rack doesn't look like it's up to the task.

My bikes carry more weight than what you're suggesting when it's only me on them. So I know that part is doable, but the wheels will need to be specially built. However, I would not sit a full size adult on a rear rack at 15mph, let alone 30. I doubt your passenger would appreciate going so fast while perched on such a hokey contrivance. It's asking for trouble.

Wouldn't it be more fun, more comfortable, and safer to build an e-longtail or e-tandem? A longtail cargo bike could have plenty of other uses besides carrying a passenger, too. It doesn't have to go as fast as your single bike, and it might be more pleasant and sociable if it doesn't.

 

[Tommm]

Not possible to comfortably cruise that fast with that much weight without a rear suspension. Then it becomes difficult to find a suitable rear rack for a rear suspension bike.

 

[LeftieBiker]

Imagine a 150lb battery there, plus the real battery.

 

[ZeroEm]

Trailer would be a good option, hook up when needed.


or smaller

 

[Bigwheel]

Looks too wide to me and that will make it uncomfortable for the passenger to ride with their feet on the pegs. I suggest an X'tra cycle kit you might find on CL or eBay...

 

[markz]

How about a longtail with an integrated welded on frame?
Or weld up your own contraption, but longtail would be crucial for carrying such a heavy load on the back.

 

[speedyebikenoob]

Thanks for the responses everyone. The reason I want to stick with this bike is because I never really *need* to take another passenger, but it's more for short sprints around town for fun. The time commitment and extra cost wouldn't be worth it to me to build another bike specifically for carrying two people because of how rarely it would get used.

The seat doesn't have to be extremely comfortable either as I definitely don't need it to do long distance. My main worry was over the rim somehow breaking and causing an accident.

 

[LeftieBiker]

If the rim is your only concern, then I suggest you go to a motorcycle rim and, if possible, motorcycle spokes.