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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 06-30-2014, 09:34 PM
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maniac57 maniac57 is offline
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Thumbs down Still want to argue about rubber mounting?


Look carefully.
See the white pad between the mount plate and frame under the Ubolt?
Notice the flattened frame tube? Caused by overtightening to try and stop inevitable engine movement caused by rubber.
Notice the visible distortion and damage on the chunk of downtube still visible?
Also notice the damaged area (paint worn off where engine rubbed) clearly visible on the broken section of seatpost tube from VIBRATION causing ENGINE MOVEMENT.


DON'T USE RUBBER OR ANY TYPE OF COMPRESSIBLE MATERIAL IN YOUR MOTOR MOUNTS.
*Wipes spittle off monitor screen*
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Old 06-30-2014, 09:38 PM
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Default Re: Still want to argue about rubber mounting?

Looks like a 'won't let me type the appropriate thing' moment.............
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Old 06-30-2014, 10:45 PM
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Default Re: Still want to argue about rubber mounting?

I agree... Solid mounting is the way to go, and I noticed a LOT less vibes were transfered after I welded mounting tabs to bolt my engine directly to the frame, If you can move the engine around with your hands after it's installed it's going to vibrate badly and eventually saw thru the frame tubes like the pics above
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Old 06-30-2014, 11:07 PM
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Default Re: Still want to argue about rubber mounting?

Ditto, about forty times. Although Maniac's photo example is worst case scenario, its is almost inevitable that something bad is going to eventually happen with a rubber mounted engine.

We'll get the arguments that cars and motorcycles use rubber mounts but that argument doesn't hold up because cars and bikes use a steel/rubber/steel sandwich style that removes engine vibrations from the mounts and fasteners. Not true when folks try to stick rubber between the engine and the frame then use the stock mounting parts over it. Totally different concept from automotive/motorcycle/aircraft/boat/ engine mounts.

Thanks, Maniac for helping to dispell an old myth about "reducing vibration" thru rubber mounts. Any builder thinking of using rubber/resilient material, needs to read this one.

Tom
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Old 07-01-2014, 12:14 AM
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Default Re: Still want to argue about rubber mounting?

Holy cow man! That's a sad ending for a good bike frame...
I hope the rider was not hurt when it failed!

So..... What are you going to do now? make it into a drop loop frame?
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Old 07-01-2014, 12:52 AM
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Default Re: Still want to argue about rubber mounting?

It's worth noting that this build's muffler shoulda been secured as well; that free-cantilever can really amplify vibes.
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Old 07-01-2014, 07:40 AM
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Default Re: Still want to argue about rubber mounting?

Cool bike bro. How does she ride?
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Old 07-01-2014, 08:03 AM
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Default Re: Still want to argue about rubber mounting?

Maniac, can you enlighten me? What is it about using a dampening material that is causing the failure? Is it just due to way its being used inhibiting the the stability of the mount?
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Old 07-01-2014, 08:36 AM
sboricic123 sboricic123 is offline
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Default Re: Still want to argue about rubber mounting?

The bike frame looks like scrap metal now. I think the picture should be "sticky" on the mounting forum for other new riders.
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Old 07-01-2014, 09:04 AM
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Default Re: Still want to argue about rubber mounting?

Quote:
Originally Posted by wret View Post
Maniac, can you enlighten me? What is it about using a dampening material that is causing the failure? Is it just due to way its being used inhibiting the the stability of the mount?
I'm not maniac but the flexible material aka rubber sets the motor up to rock
back and forth creating more vibes not less, steel to steel solid is the only way
to reduce that and one thing I've never heard brought up is seats with springs
Where a small vibe can be greatly amplified IMHO
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