JACKS FOR EBIKE?

[Base]

OK, maybe I'll give it a try.

My house was built in 1942, so the timbers are old.

we've got those https://hollandbikeshop.com/en-gb/b...uperlift-bicycle-rig-up-to-57kg-black-734067/

same system. Personally I would use a different cord, the ones which come with these systems are rather poor. and yes they work. I do not own these but a relative does.

 

[Gionnirocket]

Sister the joists with equivalent dimensional lumber, or better yet, 3/4" plywood. Lag the sandwich horizontally. Lag the hoist to the underside of the joist inside the sandwich.

I'm not sure I would trust that..
I'd sister the beam with an equivalent steel one and make sure it went the full legnth of the joists resting on the joist supports. Then I'd add a steel column on each side of each stationary pulley just to be sure.
Your lifting a bike... Not a car.
I'm in +100 year old 2x10 floor joist so if you're in 2x4 roof/ceiling rafters maybe then I would add some lumber. 2x6 and above you're fine

 

[Gionnirocket]

we've got those https://hollandbikeshop.com/en-gb/b...uperlift-bicycle-rig-up-to-57kg-black-734067/

same system. Personally I would use a different cord, the ones which come with these systems are rather poor. and yes they work. I do not own these but a relative does.

I agree the cord could be better... But two years in and they still have all strands in tact.
I plan on getting some parachute cord if it ever does give me a reason for concern.

 

[stompandgo]

I'm not sure I would trust that..
I'd sister the beam with an equivalent steel one and make sure it went the full legnth of the joists resting on the joist supports. Then I'd add a steel column on each side of each stationary pulley just to be sure.
Your lifting a bike... Not a car.
I'm in +100 year old 2x10 floor joist so if you're in 2x4 roof/ceiling rafters maybe then I would add some lumber. 2x6 and above you're fine

1-1/2" of plywood is much, much stronger than equivalent softwood 2x dimensional lumber.

 

[Gionnirocket]

1-1/2" of plywood is much, much stronger than equivalent softwood 2x dimensional lumber.

I concur.
My point was that we are lifting at max a 100lb bike with the load spread between at a minimum 2 points of the structure. If it's built to code there's no need to over think it.
@PCeBiker if you end up being perpendicular to your joist... Just use a 2x4 to span the 3 or 4 joist and you can put it exactly where you want.

 

[stompandgo]

Take a look at the picture again. As I said, I'm not concerned about the undersized lumber being able to support 100 pounds. I'm concerned that the roof is not structural, and that deflection of the joists will cause the roof to leak over time.

Carry on.

 

[Gionnirocket]

Take a look at the picture again. As I said, I'm not concerned about the undersized lumber being able to support 100 pounds. I'm concerned that the roof is not structural, and that deflection of the joists will cause the roof to leak over time.

Carry on.

ahhh... That's where the disconnect is. Gotcha.
I believe those photos are from the aussie mate not Mr. PC so we were talking about two different situations.
Looking at the photos it's hard to know for sure but they look like 2x6 cross members and 3x3 roof rafters. Size wise that's good but the spacing between seems to be a bit heavy. And yes the roof adds no integrity. The span of the 2x6 looks so short that he's probably OK. But I guess adding some reinforcement couldn't hurt as everything is wide open and easy to work with.