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Discussion Starter · #1 ·
i have searched up and down on here looking for old threads that explains how to figure out how much stretch a trump hard tail has,with no avail.
anyone have a method or know how to tell?
and no,i dont need to know this to sell something. i need to know it for a frame im picking up for my motor.
any help would be great. thanks.
 

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Wouldn't it just be the distance from motor drive gear to the rear axle.

And the stretch is the additional inches away from the stock distance.
 

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Discussion Starter · #3 ·
Wouldn't it just be the distance from motor drive gear to the rear axle.

And the stretch is the additional inches away from the stock distance.
may-be. but what is the stock distance of a bolt on hard tail?

it seems like there should be a way to pull a measurement from one point to another to find out if its stock or 2,4,or 6 over.
 

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Wouldn't it just be the distance from motor drive gear to the rear axle.

And the stretch is the additional inches away from the stock distance.
that sounds as good as any or just figure about where the axel should be if there isnt one there youll be within an " or so. I cant give the stock measure until tomorrow...
 

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do you have a stock swingarm? you could measure the distance from the swing arm pivot, to the wheel axle, then compare that distance to the bolt on hardtail, I think that the swingarm part of the frame is on the front loop part, so you could use that to measure from still.
 

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Discussion Starter · #6 ·
i dont have a swingarm section.
i was just wondering,because all these people sell these hard tail sections,and they say,"2","4","6" over stock. so there has got to be a way to tell just by looking at the hard tail section without even really having it bolted up as well,i would think?
 

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Here you go, the first one is no stretch


This one is 4 over supposedly:
 

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Cant you take a tape and a stock Trumpy. Measure from the rear hole on the frame where it would bolt on to, to the front of the axle slot. Then you could measure any other rear section from the bolt hole to the same spot and compare?
 

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don't quote me, but i believe its 17.5" from swingarm rod to back of axle slot on a stock bike. Same for a hardtail, just subtract 17.5 from what you get. If your swing arm mounts are cut off, just guesstimate. You know where they normally are. I'm pretty good at just looking at one and being able to tell what it is. If you want, shoot me a pic.
 

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Discussion Starter · #13 ·
you looking to build something or check some thing?
im building a 69 bonnie chopper. chrome frame etc.
i was about to sell the rear section,but decided to keep it. it looks 4 over to me,but its [playing tricks on my eyes.

then i just figured i would like to know how to tell.
 

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The chromoly frame you had for sale looked at least 4" stretch...could be wrong, but it looked like there was a lot of room between the rear tire and the vertical frame tube....i can stick a swing arm on a frame i have and post a measurement in the am....
 

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Discussion Starter · #16 ·
The chromoly frame you had for sale looked at least 4" stretch...could be wrong, but it looked like there was a lot of room between the rear tire and the vertical frame tube....i can stick a swing arm on a frame i have and post a measurement in the am....
that would be cool man. thank you.
yes,i thought it was like a six over,but wasnt sure. thats why i put it up,but then decided to keep it for my build...but forgot to take it down earlier before starting this thread.
no,its not for sale now. :rolleyes:
 

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looks like from swingarm pivot to front of axle slot is 16".....stretch mine so the backbone is a straight line to the axle...comes out as a 4" stretch and a 2-3" drop.....so my measurement from swingarm pivot to axle slot is 20"
 

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Discussion Starter · #18 ·
cool. thanks man. mine reads 21,but the axle plates on this hard tail section are very different from any i have seen before. so my guess is that it's really 20 inches,which would bhe 4 over...but Todd and i talked and we thought it was 2 over.:confused:
well...i gues im good to go as long as it isnt 6 over.:rolleyes:
 

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This question seems to come up fairly often , maybe this will help members who are searching .
My reference book gives the following measurements for wheelbase ;

`47 Speed Twin (telescopic forks) ..........54"

`55 Speed Twin (swing arm ) .................56"

`59 Speed Twin (unit engine) .................52.75"

Can`t find a figure for unit 650 , can anyone chip in ?

If the hardtail drops the frame in the rear , this will lengthen the wheelbase , because it kicks the forks out . Running shorter forks will obviously shorten the wheelbase .

Hope this helps someone .
 
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