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Cortina Hard Tail Build

Hi 12,
For pics of the basic bike, just google " GT IT1" , they made it in 2006 and 2007.
The nice thing is the rear swing arm is really light, and resembles a motorcycle swingarm. GT has no spare parts for my bike, so I'm stuck with what I have. It has 'one of' cnc machined sprocket parts on it, for example. I am preparing my second mill for cnc, so I can make parts as needed. I also got a good deal on 135 lbs of scrap magnesium 1" and 2" plate,and I'm really looking forward to machining some of that. It cuts nice, and weighs 1/2 of the AL version.
I have to make a custom chainring adapter for the rear sprocket, to reduce the load on the little 8 speed gearbox.
If you have ever seen the exploded view of those shimano's, you would be as scared as me for it's survival. :D
Also the higher the chain speed, the less stress on the chain there is.

Roy, on the sound ( belt vs chain ) I'm really just interested if one sounds more irritating than the other, for innocent bystanders, as it were.


12p3phPMDC said:
Hi Lesdit,

Do you have any pics of the 8 speed hub as an intermediate transmission?
I'd be really interested in seeing them...
I like the idea of divorced transmissions for some reason...guess they remind
me of a motorcycle... :wink:

Thanks....
 
sounds and looks very interesting, i must say!

im doing a similar build, once my stuff finally gets here, and from what ive found out is that you pedal at 60-75rpm offroad, 75-90 casually around town, and 90+ for racing, so a crank rpm of nearly 200rpm is huge... i am planning on around 65rpm at the cranks, and will work from there. my thinking is if i gear it to pedal speed, then i can use the bike gears to adjust the speed, so can always pedal to increase speed and range of my bike, without having to pedal at a ridiculous speed (i want a lazy casual ride as well as a hardcore downhill). this means i can run the motor at about 80% rpm, so it should be most efficient, plus easier on hard startups. thats my theory anyway, your experience suggest otherwise?

i really like your drive system, nice and neat, i was planning on having mine as tight down to the bottom of the triangle as possible, but may change it to vertical up the seat post now...
 
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