New Engine!!! Need help about chain drive

[brendonv]

How does 10,60,10,44 sound? Im thinking ill get a 44T HT sprocket from ebay as its easier to put on the spokes. Ill put a 10T on the Clutch drum, Get a bike pedal hub thing and put a 60T one one side and a 10T on the other, then run that to the 44T on the wheel. I wont space out the sprockets to much as i dont want the massive thing all over the back, ill have it really close then maybe make a nice box to go around it all then paint it black so its a thin gear reduction box. From the engine to the first gear will be about 100mm then apart from the other will be about 50mm then down to the 44T will be about 400mm. So it will look like a Staton-inc gear reduction box.

 

[duivendyk]

I don't believe you,that's a very steep hill,over 100 m rise over 300 m.People (myself included) tend to over estimate the steepness of hills.Over 10% is quite steep.If you want to get scientific about it,do the following.
1)get a carpenters level and a ruler,measure lenght of level L.
2) hold level horizontally against hill
3) with your ruler measure distance D from road bed to
bottom of level,at it's other end.
4) grab calculator,divide D by L and tell me.
What's approx. weight of you + bike + motor about 100kg?With that info I'll do some number crunching,do you have multispeed derailleur bike or what exactly.

 

[brendonv]

I don't believe you,that's a very steep hill,over 100 m rise over 300 m.People (myself included) tend to over estimate the steepness of hills.Over 10% is quite steep.If you want to get scientific about it,do the following.
1)get a carpenters level and a ruler,measure lenght of level L.
2) hold level horizontally against hill
3) with your ruler measure distance D from road bed to
bottom of level,at it's other end.
4) grab calculator,divide D by L and tell me.
What's approx. weight of you + bike + motor about 100kg?With that info I'll do some number crunching,do you have multispeed derailleur bike or what exactly.

Im only 14 so the total weight is about 60kg, my bikes a 8 speed mountain bike. Yeh the last estimate wasnt the best, my street it about a 5% incline for about 300m. The steepest hill around me which i might need to go up is about 30% incline for about 20m. I can get up it easy with my friction bike pedaling as well. I hopefully want to start getting parts either tomorrow or the next day and build it on the weekend and during the week.

Thanks for your help so far.

From Brendon.v

 

[duivendyk]

I think you'll have to forget about that steep hill,you'd have to gear down so much,you'll be revving that engine like crazy to get any speed on the flats.That's the problem if you don't have a gear box.I would give 25:1 a try,if you can change gears by changing the small sprockets it's much less of a hassle,overhere you can get smaller ones than 10t,that would give you some room to maneuver in terms of reduction.Good luck.

 

[brendonv]

thanks, i dont understand what the whole 25:1 thing means, could u just tell me what sprocket i need here and there. Like yeh i no its a ratio but i dunno how to work it out. I drew a picture of what the gearing will sort of look like.

Thanks again.

From Brendon.v

 

[duivendyk]

OK, it means a total reduction of 25 which you can't do in one stage,so two reductions of 5 will do: 5* 5=25 or 6*4=24
(*means multiplication) so you could use 10t working with 50t in each reduction 10/50 + 10/50 (overall 25) or 8/40 + 8/40 ,or 8/48 + 10/40 reduction (overall 6*4=24) or 10/40+8/40 (overall 20).Is this clear now?

 

[brendonv]

ahhh i understand now

 

[brendonv]

Well i got my two 10T sprockets, mm so nice and shinny. Ill have pics later. Now i need two 50T, ill go to the tip n see if i can score two BMX 50T sprockets out of the big bin of all different sprockets and cranks. Should have my build done by later next week.