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Mounting Techniques for Bicycle Motors Every frame is different. Share and ask questions about mounting your engine kit to your frame or rack

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  #1  
Old 02-18-2011, 04:47 AM
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bairdco bairdco is offline
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Default How To: Spreading Your Frame for Clearance

this was taken from : Sheldon Brown: Bicycle Frame/Hub Spacing

Spreading the Frame
There are a number of ways to do spread a frame. Probably the easiest way is to use a lever. A piece of 2 x 3 or 2 x 4 lumber, roughly 5-6 feet long works well for this:
1.Remove the wheels, fenders and any seat-tube mounted bottle cage.
2.Lay the bicycle on its side with the handlebars turned to face upward.
3.Insert the lumber through the rear triangle, so that it goes underneath the upper rear fork end, and above the seat tube. The lumber should extend out past the rear end of the frame.
4.Place the far end of the lumber onto a chair, crate or other raised structure, so that only the head-tube/fork area of the bike is in contact with the floor.
5.Press down gently on the lumber where it crosses on top of the seat tube.
6.Measure the spacing to see if it has changed.
7.If the spacing hasn't changed, try again, pressing a little bit harder. Repeat until you get a result, applying a bit more force each time, until the spacing has increased by about half the total amount you are seeking.
8.Turn the bike over, and repeat for the other side.
In the illustrations below, the stays will be bent to the left (up in the photos) by pressing down on the end of the 2 x 4.
The other end of the 2 x 4 is on top of a stool. The longer the 2 x 4, the less force is needed.

The 2 x 4 is under the left fork end,
widening the spacing by pulling the left side upward The 2 x 4 is under the right fork end,
narrowing the spacing by pulling the right side upward
The bike does not actually need to be stripped down this far, most parts can remain in place.
Attached Images
File Type: jpg frame-spacing-l.jpg (5.6 KB, 505 views)
File Type: jpg frame-spacing-r.jpg (5.9 KB, 441 views)
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  #2  
Old 02-18-2011, 06:37 AM
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The_Aleman The_Aleman is offline
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Default Re: How To: Spreading Your Frame for Clearance

Great write-up bairdco! IMHO, everyone with pedals should have Sheldon Brown's site bookmarked! He was/is an inspiration to me, dating way back to my pedalhead days. May he RIP.

Framespreading alternate method:

I had to spread my frame on "OCD" when I went to install my X-RD3'd wheel in the rear dropouts. GAH, needed another .375"! I didn't use the great man's method for mine because the frame was not a day back from the powdercoating shop.

Instead I created my own framespreading tool like any other industrious MaBer might be apt to do. Here's the parts I used:

(2x) .250" bar stock, 2.5" x 6" (2" should also work)
(2x) 0.5" coarse-threaded rod, 6" (12" if no coupler)
(2x) 0.5" nuts and fender washers
(1x) 0.5" coupler for threaded rod (you can skip this if using 12" rod)
An old non-knobby tire and 4 zipties (can sub lots of ductape for either/or)

How to build the framespreader with above parts:

1) Drill a 0.5" hole in the center of each plate. Take the old tire and cut a couple pieces that will cover one side of each plate, and don't forget the hole. Secure tire to one side of each plate using zipties or ductape. The tire is so you won't scratch frame when spreading it.

2) Take the threaded rods and thread them into the coupler. Thread the nuts onto the rod all the way to the coupler. Add washers. Slide plates onto the rod.

Done! My notoriously junky cam has no batteries, so I supplied a crude MSPaint drawing. I'll update this post at another date with a proper pic. To use this tool, you simply tighten one of the nuts until you achieve the proper spreadage. Hope this helps!
Attached Images
File Type: jpg frame tool.jpg (28.1 KB, 519 views)
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  #3  
Old 02-18-2011, 07:12 AM
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Default Re: How To: Spreading Your Frame for Clearance

i just use a bottle jack, theres some spring back when spreading a frame so go in small steps untill you get it where you want it.
to spread the front part of the chain stays use a threaded rod or an old axle to keep the axle area from spreading and spread the area behind the seat tube with a port-a-power for fitting wide tires.
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  #4  
Old 02-18-2011, 02:01 PM
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killercanuck killercanuck is offline
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Default Re: How To: Spreading Your Frame for Clearance

That's cool bairdco, not just for hub clearance but for shifting the whole hub position.

Aleman's technique is good just for hub spacing, but ain't much out there cheaper than a 2x4

That's a cool idea camlifter, throw a hub in there while you're cranking on it so both sides move the same.

Great post!
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Old 02-18-2011, 02:07 PM
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Default Re: How To: Spreading Your Frame for Clearance

Just might have to refer to this for My Panther and sturmey.
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  #6  
Old 10-30-2012, 05:06 PM
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Wink Re: How To: Spreading Your Frame for Clearance

Quote:
Originally Posted by killercanuck View Post
That's cool bairdco, not just for hub clearance but for shifting the whole hub position.

Aleman's technique is good just for hub spacing, but ain't much out there cheaper than a 2x4

That's a cool idea camlifter, throw a hub in there while you're cranking on it so both sides move the same.

Great post!
I hate to disagree with you but I used something like Aleman's technique
had to spread rear forks almost 3 inches for the HD axle, do that with a 2x4 and NOT break it.


and remember that advice you give can trash someone else's frame, not yours!!!
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  #7  
Old 10-31-2012, 12:31 PM
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killercanuck killercanuck is offline
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Default Re: How To: Spreading Your Frame for Clearance

Quote:
Originally Posted by Desert Rat View Post
I hate to disagree with you but I used something like Aleman's technique
had to spread rear forks almost 3 inches for the HD axle, do that with a 2x4 and NOT break it.


and remember that advice you give can trash someone else's frame, not yours!!!
FYI - I've used biards technique with a hub in place like Cam mentioned to straighten a frame once, and another time to give me upper chain clearance.

I didn't just stomp on it, let it flex and give it the time to bend. Depends on the frame you're using too I guess, eh? ie. cruiser/mtb, alum/steel...
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Last edited by killercanuck; 10-31-2012 at 12:34 PM. Reason: mixed up names
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  #8  
Old 12-13-2012, 01:33 PM
brad2274 brad2274 is offline
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Default Re: How To: Spreading Your Frame for Clearance

never thought of using a 2x4, i usually just use a spare tire car jack(the real tiny wind up ones) for bending forks, frames, and cranks.
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  #9  
Old 12-27-2012, 01:35 PM
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Default Re: How To: Spreading Your Frame for Clearance

Quote:
Originally Posted by The_Aleman View Post
Great write-up bairdco! IMHO, everyone with pedals should have Sheldon Brown's site bookmarked! He was/is an inspiration to me, dating way back to my pedalhead days. May he RIP.

Framespreading alternate method:

I had to spread my frame on "OCD" when I went to install my X-RD3'd wheel in the rear dropouts. GAH, needed another .375"! I didn't use the great man's method for mine because the frame was not a day back from the powdercoating shop.

Instead I created my own framespreading tool like any other industrious motorized bicycle rider might be apt to do. Here's the parts I used:

(2x) .250" bar stock, 2.5" x 6" (2" should also work)
(2x) 0.5" coarse-threaded rod, 6" (12" if no coupler)
(2x) 0.5" nuts and fender washers
(1x) 0.5" coupler for threaded rod (you can skip this if using 12" rod)
An old non-knobby tire and 4 zipties (can sub lots of ductape for either/or)

How to build the framespreader with above parts:

1) Drill a 0.5" hole in the center of each plate. Take the old tire and cut a couple pieces that will cover one side of each plate, and don't forget the hole. Secure tire to one side of each plate using zipties or ductape. The tire is so you won't scratch frame when spreading it.

2) Take the threaded rods and thread them into the coupler. Thread the nuts onto the rod all the way to the coupler. Add washers. Slide plates onto the rod.

Done! My notoriously junky cam has no batteries, so I supplied a crude MSPaint drawing. I'll update this post at another date with a proper pic. To use this tool, you simply tighten one of the nuts until you achieve the proper spreadage. Hope this helps!

I did the same thing pretty much to get space for a rear brake. Pic attached
Attached Images
File Type: jpg spread-em.jpg (93.7 KB, 270 views)
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  #10  
Old 01-29-2013, 01:03 AM
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Desert Rat Desert Rat is offline
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Exclamation Re: How To: Spreading Your Frame for Clearance

question on spreading, I mounted a HD axle and had to spread my frame open like 3 inches.
what I would like to know from the experts, can you put a torch to rear
forks (for lack of better word) to release the stress without doing damage
to bike? I believe I can since the steel is not hardened a good heating and slow
cooling should release stress without doing damage
What are your thoughts?
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