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Old 12-21-2012, 02:49 PM   #121
sailah OP
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Quote:
Originally Posted by larryboy View Post
25 degrees is good, 18% is awfully stiff IMHO. How is the rake and trail at race sag, you have the front strapped down too for your calcs?
Guess I have the ratio calculated incorrectly, see below. I'll report back with the new number

Quote:
Originally Posted by jar944 View Post
You are calculating incorrectly, you need to know your total travel to get the % sag.

660mm isnt total travel it's a random measurement between the extended susp and the frame.

Take the difference of the shock bottomed and fully extended then use that number instead of 660

or just use 335mm (rear travel for a KTM RFS) 117/660=34% typically KTMs run about 37/115mm
Thanks. Just so I'm clear you meant 117/335mm=35% right?

Quote:
Originally Posted by Salsa View Post
It sounds like you are getting there.

If you set the mount to get the total travel you want, the only other variable is how much progression you could get with that same total travel. You should be close enough where ever you put it.

I looked at the Race Tech KTM - PDS SHOCK SYSTEM Page
http://www.racetech.com/articles/ktm.htm
and used the graphs to estimate the geometry gives a geometric change of rate of 1.45 from the top to the bottom of travel. The spring is effectively 45 % stiffer at the bottom of travel vs the top. With the progressive spring, the combined progressiveness is 2.65 (165 % stiffer).

Sounds good to me.

Try it with the spring you have and if you want a softer ride then get the progressive spring.

Don
Will do. As I have found there's a big difference in designing in theory and actually getting out there and putting a bunch of miles on to really decide what works. Because the suspension is so critical to everything else, it's not like footpegs that can get relocated easily. I really want to get this right the first time. As always, I'll give the +/- when I ride it.

Spent an obscene amount of time drawing, measuring and drawing and remeasuring to get the frame mounts and crossbars mapped into my CAD program so that I can draw the suspension mounts to have them waterjet cut.
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Old 12-21-2012, 03:05 PM   #122
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Nice and productive today. Designed out the frame tubes so I could design the shock mount in CAD. Printed out a couple tests then I made one on a manila folder. I think I will have my waterjet guy cut these out and tack them in place to give it a full cycle. The circles on the body are for 7/8" tubes that I will weld across both plates to get the correct 24mm distance that the shock needs.





It was hard to hold everything in place to get the pic. Hope it makes sense. The arm will be similar to what I made on the CBR but will also pick up the lower tube to prevent any rotational stress on the top tube. I think welded together it will be very strong and help tie the original frame together



Then I decided to tackle the subframe. As you may have noticed, the Ninja subframe is not symmetrical due to their shock being on the extreme right side. I decided to make it sorta symmetrical by replacing the top tube with one I made, and also making a diagonal from the main frame back up to the subframe. Should be much stronger than the original. I need to put in some gussets and also there is a cross bar I haven't done yet.

I was pleased with how the bends came out. I rolled the back half on a tubing roller, then went to the tubing bender to make the recess for the shock reservoir. I did not see a clean way to butt the tube into the frame so I decided to make a scarf joint instead and get a long weld bead on it. that joint is in tension anyways and I might brace it later.

Here's what it looked like before I cut it



And after





Need to complete this tube across. The wall thickness of the tubing they used is retarded thick. They could have made the whole thing so much stiffer and lighter by using thinner wall and larger diameter. Oh well.

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sailah screwed with this post 12-21-2012 at 03:19 PM
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Old 12-21-2012, 03:32 PM   #123
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"Thanks. Just so I'm clear you meant 117/335mm=35% right?"

I think Jar944 meant the measurements were at the shock. "typically KTMs run about 37/115mm"

37 mm sag of shock travel out of 115 shock travel. But I am guessing.

Don
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Old 12-21-2012, 03:49 PM   #124
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Quote:
Originally Posted by Salsa View Post
"Thanks. Just so I'm clear you meant 117/335mm=35% right?"

I think Jar944 meant the measurements were at the shock. "typically KTMs run about 37/115mm"

37 mm sag of shock travel out of 115 shock travel. But I am guessing.

Don
Makes sense thx
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Old 12-21-2012, 04:04 PM   #125
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Quote:
Originally Posted by sailah View Post
Guess I have the ratio calculated incorrectly, see below. I'll report back with the new number



Thanks. Just so I'm clear you meant 117/335mm=35% cut.
Yes sorry.
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Old 12-21-2012, 04:12 PM   #126
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Quote:
Originally Posted by Salsa View Post
"Thanks. Just so I'm clear you meant 117/335mm=35% right?"

I think Jar944 meant the measurements were at the shock. "typically KTMs run about 37/115mm"

37 mm sag of shock travel out of 115 shock travel. But I am guessing.

Don
115 race sag
37 static sag
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Old 12-21-2012, 04:15 PM   #127
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Quote:
Originally Posted by jar944 View Post
115 race sag
37 static sag


Btw your bikes are sweet, I remember a year or two ago reading about the rfs conversion then saw your sig line. Nice
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Old 12-25-2012, 02:11 PM   #128
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I like this thread.
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Old 12-26-2012, 10:42 AM   #129
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I like this thread.

Thanks man appreciate it I like doing it so it's a win-win.

Worked a little yesterday and bent up some aluminum channel to hold the Rotopax 1.75G fuel cell.

Finished my shock mounts and getting them waterjet cut, next step is to tack them on and recheck the suspension numbers. I really hope I didn't screw it up because that was a lot of thinking and my brain can't handle any more

I've entered the Ninja in the ALCAN 5000 for 2014 http://www.advrider.com/forums/showthread.php?t=777051

I really hope it has a bunch of miles on it before then so I can be confident it will make it. Hell the way I building these bikes I'll probably have a couple more done by then

Work will be slow for the next week, folks are coming to town and I don't want to start thinking fuel system until the shock mount is done. I have some radical ideas for the fuel tank (s) but it might be too much work, I'll explain when I get there.

Merry Christmas gearheads!!
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Old 12-26-2012, 03:09 PM   #130
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Merry Christmas gearheads!!
Merry Christmas

Help me understand how you are setting sag numbers with a good 40lbs of stuff (never mind the gearhead holding onto the bars) not on the bike, is this SWAG
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Old 12-26-2012, 03:48 PM   #131
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Merry Christmas

Help me understand how you are setting sag numbers with a good 40lbs of stuff (never mind the gearhead holding onto the bars) not on the bike, is this SWAG

I was on the bike setting sag. I purposely sat on the pillion seat to weight it even further. I also wore a really heavy jacket and put a 25lb dumb bell on the frame. I'm probably within 10% of the final weight, but yeah SWAG

Missing tank, battery, some plastics, lights. which is probably close to the dumbbell weight. I just want to get in the ball park, can always throw in a heavier spring or more preload.
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Old 12-26-2012, 07:17 PM   #132
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I hope good ole Sandy Claws stuffed your stocking with lots of Sawzall blades, abrasive cutoff wheels, and TIG filler rod.
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Old 12-26-2012, 07:50 PM   #133
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ain't skeered.
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Old 12-28-2012, 06:13 PM   #134
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anyone here have a header?
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Old 12-28-2012, 06:31 PM   #135
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New to Some Assembly Required

This build is way beyond my skills, but very interested in seeing it come together. Great job. Subscribed.
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