I'm making a new flying fox for my kids. About a 20m run and a 3m drop. I've got the steel posts in and the steel cable up. I tried using a cheap pulley but it was crap so I've ordered a quality climbing pulley. I'm sure this thing will be fast now so I've decided I need a nice rebound spring on the end of the cable but I don't fancy paying $200 for a spring. Surely I could source a second hand spring from somewhere. Any ideas?

What is a rebound spring? and maybe a car suspension spring? Leaf or coil.

Yeah, coil. It needs to wrap the cable.
Car is probably too wide

Spring from the front forks of a dirt bike Should be able to get one from a motorcycle wrecker
The climbing pulley will wear very quickly as it's made to run on rope not steel cable

Run a tether/retrieval line from the origin point, attach it with a section of bundled bike tubes or appropriate bungee line if you can find it.
Should be able to suspend it in a way it doesn't interfere with the rider

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IanR said..
Spring from the front forks of a dirt bike Should be able to get one from a motorcycle wrecker
The climbing pulley will wear very quickly as it's made to run on rope not steel cable

I was thinking motorcycle wrecker but the local wrecker is such a douchebag

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D3 said..
Run a tether/retrieval line from the origin point, attach it with a section of bundled bike tubes or appropriate bungee line if you can find it.
Should be able to suspend it in a way it doesn't interfere with the rider

More hassle than it's worth. The public ones use a spring.

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Psychojoe said..
.....The public ones use a spring.

Maybe a pair of bolt cutters ?

Then rob the spring from the public one.

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Carantoc said..

Psychojoe said..
.....The public ones use a spring.

Maybe a pair of bolt cutters ?

Then rob the spring from the public one.

Theirs is more of a damper. I want something that'll push the kids halfway back up the hill.

What about using a counterweight, sort of like they have hanging off the railway electric wires?

I'm thinking something that stretches rather than compresses would be better for flinging them back up the rope.

I can't picture how it would work but I'm imagining those ropes that allow a float to go up and down with the tide.

With several pulleys for a sheep shank system.

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remery said..
What about using a counterweight, sort of like they have hanging off the railway electric wires?

I'm thinking something that stretches rather than compresses would be better for flinging them back up the rope.

I can't picture how it would work but I'm imagining those ropes that allow a float to go up and down with the tide.

With several pulleys for a sheep shank system.

Far too complex. Simple wins today

Kids are too soft these days. Why waste time with a spring. Just a few foam cushions stapled to the post/tree. Make them make their own way back.

Maybe attach a bungie cord to them from the other side and get them to tie the knot at the right length, in case it is wrong.

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psychojoe said.

Far too complex. Simple wins today

Motorcycle forks have springs, compression and rebound damping for a reason. Simple doesn't work today.

You can get replacement springs through Temu and Aliexpress quite cheap but I doubt they will bounce your kids half way back up

www.temu.com/ul/kuiper/un9.html?subj=goods-un&_bg_fs=1&_p_jump_id=894&_x_vst_scene=adg&goods_id=601099527598205&sku_id=17592265142026&adg_ctx=a-ad6a1884~c-c9236cb2~f-c0e80054&_x_ads_sub_channel=shopping&_p_rfs=1&_x_ns_prz_type=-1&_x_ns_sku_id=17592265142026&mrk_rec=1&_x_ads_channel=google&_x_gmc_account=710728018&_x_login_type=Google&_x_ads_account=2720833615&_x_ads_set=20878039836&_x_ads_id=157413511615&_x_ads_creative_id=685403347863&_x_ns_source=g&_x_ns_gclid=Cj0KCQjwiYOxBhC5ARIsAIvdH52jGrzOMD3t_rdK0baizkwRSwmiWMRaG9leJnZn2O3vyKBg1zjwCG4aApewEALw_wcB&_x_ns_placement=&_x_ns_match_type=&_x_ns_ad_position=&_x_ns_product_id=710728018-17592265142026&_x_ns_target=&_x_ns_devicemodel=&_x_ns_wbraid=Cj4KCAjw5v2wBhBNEi4AvZ7ZAO_H2W7YyZ-tjG503S7JIoEL7tgm0UnlY_oipoBiQi_njYt574wNXvvUGgIo_w&_x_ns_gbraid=0AAAAAo4mICHLYx4jkHpIoV-o3bsgnLJTK&_x_ns_targetid=pla-2088250705615&gad_source=1&gbraid=0AAAAAo4mICHLYx4jkHpIoV-o3bsgnLJTK&gclid=Cj0KCQjwiYOxBhC5ARIsAIvdH52jGrzOMD3t_rdK0baizkwRSwmiWMRaG9leJnZn2O3vyKBg1zjwCG4aApewEALw_wcB&is_back=1

Remery I don't think anyone is suggesting using the whole fork as your quite right because the rebound is controlled by oil moving through valves

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IanR said..
You can get replacement springs through Temu and Aliexpress quite cheap but I doubt they will bounce your kids half way back up

www.temu.com/ul/kuiper/un9.html?subj=goods-un&_bg_fs=1&_p_jump_id=894&_x_vst_scene=adg&goods_id=601099527598205&sku_id=17592265142026&adg_ctx=a-ad6a1884~c-c9236cb2~f-c0e80054&_x_ads_sub_channel=shopping&_p_rfs=1&_x_ns_prz_type=-1&_x_ns_sku_id=17592265142026&mrk_rec=1&_x_ads_channel=google&_x_gmc_account=710728018&_x_login_type=Google&_x_ads_account=2720833615&_x_ads_set=20878039836&_x_ads_id=157413511615&_x_ads_creative_id=685403347863&_x_ns_source=g&_x_ns_gclid=Cj0KCQjwiYOxBhC5ARIsAIvdH52jGrzOMD3t_rdK0baizkwRSwmiWMRaG9leJnZn2O3vyKBg1zjwCG4aApewEALw_wcB&_x_ns_placement=&_x_ns_match_type=&_x_ns_ad_position=&_x_ns_product_id=710728018-17592265142026&_x_ns_target=&_x_ns_devicemodel=&_x_ns_wbraid=Cj4KCAjw5v2wBhBNEi4AvZ7ZAO_H2W7YyZ-tjG503S7JIoEL7tgm0UnlY_oipoBiQi_njYt574wNXvvUGgIo_w&_x_ns_gbraid=0AAAAAo4mICHLYx4jkHpIoV-o3bsgnLJTK&_x_ns_targetid=pla-2088250705615&gad_source=1&gbraid=0AAAAAo4mICHLYx4jkHpIoV-o3bsgnLJTK&gclid=Cj0KCQjwiYOxBhC5ARIsAIvdH52jGrzOMD3t_rdK0baizkwRSwmiWMRaG9leJnZn2O3vyKBg1zjwCG4aApewEALw_wcB&is_back=1

Remery I don't think anyone is suggesting using the whole fork as your quite right because the rebound is controlled by oil moving through valves

My Chinese mate was over at the weekend. He said never buy from Temu unless you absolutely don't care about quality. Apparently they only sell China's lowest quality products.

Then spend up to a thousand dollars on quality springs
I think your local wrecker has good douche bag radar and treats people the way people treat him

Anything with that much energy to stop and then propel basckwards surely has some safety implications? what if they swing up etc? hair fingers? anyway i get a spring to cushion the landing.

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IanR said..

Remery I don't think anyone is suggesting using the whole fork as your quite right because the rebound is controlled by oil moving through valves

I was imagining the rope going through the fork spring. The would be some cushioning I just don't think it would be progressive enough to send a kid halfway back, like a stretched bungee might. Quality forks like WP only have about 12" of travel and are designed to work with a 200kg bike and 100 kg person.

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myusernam said..
Anything with that much energy to stop and then propel basckwards surely has some safety implications? what if they swing up etc? hair fingers? anyway i get a spring to cushion the landing.

Absolutely. That's why a want a safe simple spring. But that will have to wait. I had a trial run today, one of the steel posts I fixed to was existing, 6mm steel so plenty strong enough, broke the concrete floor around it. Need to try again, maybe a guy rope.

if you have verge junk pickup in your area grab a cheapo mountain bike and pull apart the front shock theres acompression spring in there which should filt over your rope

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psychojoe said..

My Chinese mate was over at the weekend. He said never buy from Temu unless you absolutely don't care about quality. Apparently they only sell China's lowest quality products.

He probably didn't mention the slave labour from Uyghur camps also.

www.nytimes.com/2023/06/22/business/economy/shein-temu-forced-labor-china.html

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psychojoe said..
My Chinese mate was over at the weekend. He said never buy from Temu unless you absolutely don't care about quality. Apparently they only sell China's lowest quality products.

I bought this camping tent from Temu.

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CH3MTR4IL5 said..

psychojoe said..

My Chinese mate was over at the weekend. He said never buy from Temu unless you absolutely don't care about quality. Apparently they only sell China's lowest quality products.

He probably didn't mention the slave labour from Uyghur camps also.

www.nytimes.com/2023/06/22/business/economy/shein-temu-forced-labor-china.html

You subscribe to the newyork times??!