need help on project

I'm looking for help with a project l am doing with disengaged teenagers at high school

all the branches meet for a humane powered boat race at the end of the school year so far my school has had a DNF and a mid field ending

l ask you how hard is rowing :p
so this year I'm fitting a bikes to run a prop
The idea so far is remove the spokes from the rear wheel and bolt the gear that is near the pedals instead of the rim that way l can still use the gears on the 10 speed
then chain drive the rear shaft though a small bike gear ,then will run it though a diff (maybe one off a ride on mower ):?

now two questions what is a good prop for the speed that l can get my student make with this set up ??

2ND question but one more important how do you the rear gear off the hub ,there is a bearing on top ,no way of getting under it
had a test hit sitting the gear on the vice and hitting a nut washer thing inside the gear :(
worked out most of the other stuff if l cant get a mower diff free l may have to make one

hay is there a formula for gearing rpm= trust :?
may get the science class involved testing the beast

l may make it a wip if anybody is interested

simple boat plans would help :D

or ideas how to get more speed the thing is the whole job has to cost only 100$:p

Can't help with much, but to remove the cluster (sprocket) from the hub you need small tool that fits into the slots in the middle of the cluster. There are a few varieties depending on the brand, so take it to your local bike shop.

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Originally Posted by AlexS

Can't help with much, but to remove the cluster (sprocket) from the hub you need small tool that fits into the slots in the middle of the cluster. There are a few varieties depending on the brand, so take it to your local bike shop.

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thanks alex
l can make tools with the kids and teach them basic tool makeing ,can't see any slots do l have to remove the bearing first:?

made tool to fit nut inside gear assembly question do you hold the gear or the wheel hub :?

Can't help with your questions, but a few thoughts

Humane powered is different to human powered :D

How about paddle wheels or wheel instead of a prop, much easier to fix than a prop.

Use a small diff to transfer power from bike to prop shaft.

Been watching to much Scrap heap challenge :D

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Originally Posted by Cruzi

Can't help with your questions, but a few thoughts

Humane powered is different to human powered :D

How about paddle wheels or wheel instead of a prop, much easier to fix than a prop.

Use a small diff to transfer power from bike to prop shaft.

Been watching to much Scrap heap challenge :D

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one of the other teacher's team made a paddle wheel last year trying something different

got the larger gear fitted to back wheel hub:)

having trouble posting a photo:(

new computers arrrrrrrrrrrrrrrrrr

It appears you got the cluster off OK.:2tsup:

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Originally Posted by AlexS

It appears you got the cluster off OK.:2tsup:

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:2tsup:got it going to see if l can get some old bikes tomorrow and off to see if l can find something to make a diff from

I reckon you could use a bit of 3mm x 50mm flat.
Drill a hole in the centre of a suitable length to mount to a drive shaft.
Hold the flat in a metal vice over the hole, whack a 12" shifter on the end of the flat thats sticking up and twist the bar. Turn it over and do the same thing again.

I'd reckon that 150-200mm would be all thats needed.

I'd file all sharp edges and corners.

Its rough but its only going to spin slowly being pedal power so it should do

Quote:

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Originally Posted by echnidna

I reckon you could use a bit of 3mm x 50mm flat.
Drill a hole in the centre of a suitable length to mount to a drive shaft.
Hold the flat in a metal vice over the hole, whack a 12" shifter on the end of the flat thats sticking up and twist the bar. Turn it over and do the same thing again.

I'd reckon that 150-200mm would be all thats needed.

I'd file all sharp edges and corners.

Its rough but its only going to spin slowly being pedal power so it should do

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thanks

will make one like that
thinking l will rig up a test bath so l can measure the force some how :?then we can keep making props and gears and make a graph of the out comes


would 10mm drive shaft be ok to use then l can use axles from the front wheels or is it to thin