Rubber mounting tank, engine and tensioner?

I'm sure most of your guys' manuals recommend mounting your engine, tank and tensioner on bits of bicycle inner tube to prevent marring/scratching the paint on your frames. But how many of you guys actually do this? I'm about to assemble my first kit and am trying to figure out which way to go.

I can see the pros and the cons. The rubber will definitely keep the paint from getting scratched and will also reduce vibration all around. But the mounting won't be as solid as a metal to metal mount.

FUEL TANK: The fuel tank is no problem since it is fairly light and not the source of vibration or any significant load.

ENGINE: The engine is another story. Using the stock mounts and some inner tube on the engine mounts I could see how although the vibration transmission will be reduced it is not as solid a mount as using no rubber at all and the engine will have a tendency to be pulled by the chain torque to the left when the bicycle is under power. So what I thought of doing is using the rubber inner tube but also drilling a hole through the U-shaped engine straps and the bicycle frame itself and putting in a screw (a set screw of sorts) to prevent the engine from twisting under torque to the side.

TENSIONER: With horror stories of the tensioner loosening and jamming itself into the spokes I thought of using the same method as on the engine. Use the rubber inner tube and also drilling a hole for a screw to prevent the tensioner from loosening, twisting on the frame and into the spokes.

What do you guys think?

DudeZXT said:

Oh, yeah, the tensioner: just get rid of it and make your chain the correct length to begin with...

Click to expand...

I will be trying to do this when I finally get around to putting the chain on but sometimes it's just not possible due to frame clearance issues and also since I don't have too much adjustment in the rear wheel it might turn out that my chain will be either too loose or too tight after removing extra links. We'll see though.

As always thanks to all the MB gurus for the invaluable info.

OK, so rubber = bad idea. But what about the idea of locking or 'pinning' the tensioner and maybe even the engine with a set screw to prevent movement or rotation on the frame tubes?

BarelyAWake said:

More than ya ever wanted to know about the dreaded chain tensioner lol: http://motorbicycling.com/f11/chain-tensioner-suggestions-11815.html

Click to expand...

Shame on you, selfishly promoting your own thread. LOL j/k

Seriously thanks for the link. Talk about tensioner overload, no pun intended. Lots of interesting tensioner ideas. I see that right on the first page in one of the pics is my idea of pinning the tensioner as well. I guess great minds think alike. lol

BarelyAWake said:

Shameless self-promotion! OMG yer right!!1!

/bans self

Wait a mo... I'm not tryin' to sell nuffin' lol

Click to expand...

Ah but that's where the true evil genius lies. Advertising/promotion without actually selling anything.

I love the welded tensioner in the pic. Very clean setup without looking like an afterthought. If my frame wasn't already painted I'd go that route. It's hard to anticipate everything on your first build. Will definitely try something like that on my second build.

KCvale said:

Hi, welcome and good luck with your first build!

Motor Mount:
Unless your seat tube is too fat for a good fit, don't put anything there other than maybe a little locktight.
And pinning it won't counter the twist, that is what your front mount is for.
If it all possible use the dual stud mount so you have a stud on the right side of the front tube, that will counter the twist the best and it is a much longer lever than a pin at the pivot point.

Tensioner:
As you read through the myriad of tensioner ideas here you will find one common mantra of mine, if it is at all possible DON'T USE ONE ON THE DRIVE SIDE!

If chains won't match make the pedal side long and put it there.
You won't need to worry about rubber or pins or anything, the pedal side is human power and seldom used.
You don't need to use the big ugly hunk of metal tensioner for the pedal side either, a nice little one like this works just dandy.

All my pedal side needed after getting the motor side right was a single 1/2 link.

I hope that helps ;-}

Click to expand...

Thanks for the encouragement and especially the tips. This first build has been over a year in the works mostly because of work/family obligations.

Anyways, I know you mentioned that the front mount helps with the twist of the engine but I like the thought of a properly triangulated mount setup. That would obviously work the best. Two mounting points can work very well if you weld in solid mounting brackets onto the frame. With the stock straps i would think there's always a fair potential for twist unless you do the nuts up really, really tight in which case you run the risk of pulling the studs out of the case. I love your idea of the tensioner on the pedal chain though since unless all the planets are in perfect alignment and you luck out you're bound to end up with one of the chains either too loose or too tight especially if not running a derailleur to take up the slack on the bicycle chain.