Why doesn't anyone make rear mount spacers?

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Kevlarr

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Jul 22, 2009
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Mi
I've seen this time and time again, a motor mounted directly to the seat tube and some kind of hoop mount or even a double spaced mount with super long studs on the front. Now I understand if the front mount doesn't fit the frame but why do people seem to avoid spacing out the rear mount so the front is solid on the frame?

Once I spaced my rear mount out away from the block with a couple of nuts I haven't had a problem with it since.

I've thought about making spacers out of some aluminum flat bar but I've pretty much come to the conclusion of why fix it if it ain't broken. :D
 

2door

Moderator
Staff member
Sep 15, 2008
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To answer your question, Kev, I'd have to guess that mounting to the seat tube first then worrying about the front mount just seems to come natural. As a rule all of the engines will mount to the seat tube with little to no modifications so the job is half done. Fabricating a front mount due to oversized or curved down tubes is a problem that many face when mounting to anything other than a standard 'V' frame bike. Maybe its just a matter of the front mount being more easily accessed and therefore easier to work with than the rear which is somewhat hidden and hard to get to. I typically mount the rear then see what needs to be done to get the front nailed down...just the way I do it but its not carved in stone.
Tom
 

ferball

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Apr 8, 2010
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One thing I noticed on my rear mount adapter I had to fab is there is not a lot of room one the rear to mess with, you have the chain on one side, and the clutch housing on the other, and throw in a front deriler...
 

Kevlarr

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Jul 22, 2009
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Something like this in say 1/16" to 1/8" would be perfect. Maybe a kit with a few of each size.
 

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Al.Fisherman

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Sep 9, 2009
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Kevlarr, What you have pictured there is close to what I am producing as a tensionerless chain tensioning system!!
I'll post some pics soon.
Love the idea...great thought.

As far as the rear first?? If you need to do the front, why do both? I know that they are out there, but out of 5 builds I have not had one that the front matched up perfect. It takes a 75 degree "V" for a perfect fit.
 
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bairdco

a guy who makes cool bikes
Aug 18, 2009
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living the dream in southern california
i do that all the time. seems like all my kits have come with an extra mount, so i've cut them down and made spacers outta them. sometimes i need a 1/4" or so just to get the chains right so i don't need a tensioner.

i've also used the "large frame adapter" chunk of steel (used by those people crazy enough to drill holes in their downtubes...) as spacers.

and as for your idea of a spacer, i've made some exactly like that. loosen up the bolts and slide them right in...
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Here's a pic of my new 'tensionerless' chain tensioner system. (to get rid of those evil rollers.)
First you install the BMX 1/2 link on the pedal chain; then to get the engine chain tension perfect, you simply slide these shims in between the rear mount & the engine. (& as the chain stretches over time, you can simply add another shim to re-tension the chain again!
The shims are laser cut from stainless steel (to prevent rust), have a built in handle & are shaped to make them easy to install.
I've tested these on several bikes with great success.

Each kit will be sold for $30. (as pictured)

I'll post another pic of what it looks like after installed ASAP.

Anyone interested can PM me. (I'm also gonna post this in the 'swap & shop' section.)
 
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