common sense...

i was at a swap meet the other day, and i saw another motored bike in the bike rack. it was your standard, flat black 70's schwinn cruiser. basic "rat" bike.

i took a good look at it, and noticed some real death-trap "modifications."

the coaster brake arm was coathangered to the frame, the chain tensioner was crooked, and the chain was still loose. it had no left grip, the tires were bald, and some spokes were missing out of the back wheel.

i kinda just laughed it off, and forgot about it.

then i started thinking about it again. this guy's gonna die. or at the very least, get hurt.

all it takes is one fatality or serious injury, and the law will start clamping down on us (anyone remember "lawn darts?")

and reading through a lot of these "help me" threads on here, i figured i'd offer up some simple, common sense advice. it seems like a lot of you have little to no idea about bicycles in general, and adding a motor to them could be a disaster.

i'd like to point out that i'm not calling anyone out, or trying to **** anybody off, i'm just trying to save your life, and your bike. i realize a lot of you have been riding and working on bikes forever, but, judging from some of the posts out there, a lot of you haven't. so don't take offense.

the simplest thing you could do, is learn how your bike rides before you even consider putting a motor on it. ride it around, cruise it to the store, and set it up so it's comfortable. know how it reacts, stops, pedals, corners, etc.

learn how to fix a flat, grease your bearings, adjust your cones, headset, and everything else. it's all really simple, and i figure if you can manage to install a motor, you should be able to re-grease a bicycle hub. you can go to Welcome to Park Tool Company and check out the repair guides for help.

so now that you learned all of this, do it. you'd be surprised at how lousy they are greased straight from the box. and there's no bike-techs at walmart. and that bike from the thrift store? i don't think anyone tuned it up before giving it away. do it all yourself. or if you just can't handle it, take it to a bike shop and pay them 100 bucks to tune it up for you. they'll use 2 bucks worth of grease, an hour's time at minimum wage, and you'll never know how bad the guy who fixed it up for you's hangover was, until your wheel falls off.

then put your motor on it.

these aren't cars. You can’t just take it into big-o tires and tell them to fix it. once you put a motor on, your local bike shop's not gonna want anything to do with it. If there is something you can’t figure out, like rebuilding a coaster brake or true-ing a wheel, and you must take it to a bike shop, take the wheel off. Don’t bring them the whole bike.

some real simple common sense things, are:

if something is rattling or loose, it’s gonna fall off. Fenders, lights, chaingaurds, rear wheels… either fix it, or take it off. Don’t wait for it to fall off. Find all the threads on fender failures and you’ll see what I mean. If it even looks like it could fall off, fix it. If you don’t know what to do, ask. With all the people here, I’m sure someone’s already had that problem.

now for some controversy…

motor mounts.

solid is the way to go.
if you use any kind of rubber, urethane, whatever, the engine will vibrate more. And what’s worse, those vibrations will stay with the engine. Because you were right when you thought it would isolate the vibration, but the problem is, it isolated it to the motor. Say hello to the wonderful world of broken studs, twisted mounts, and nothing but problems.

if the motor’s solidly mounted, the vibrations will be transferred to the bike, and if you fixed all the loose, rattle-y parts I mentioned above, your bike will be nice and smooth and solid feeling.

chain tensioners.
almost every bike I’ve seen can be made to function without one. It might take some time, but it’s possible. I say, “almost every bike,” because with stretch jobs and unusual frames, suspension or vertical drop-outs, it might be impossible to line up without one. But the average cruiser doesn’t need it. and i don't understand why bikes with gears and derailleurs have them, since they're spring loaded, so you wouldn't have to mess with it on the pedal side...

first, buy a good chain breaker. I know a lot of people run the tensioner because it came with the kit, and they don’t have the tools to shorten the chain.
if it’s a coaster brake, buy a couple extra rear cogs. Most bikes come with an 18 tooth. Get a 17, 19, 20… they’re like 5 or 6 bucks each.

so, you’ve got your engine mounted. Now, take the masterlink and throw it away. put the rear wheel on, centered in the drop-outs, and then put your engine chain on. use your chain breaker to take off the links you don’t need. If you have to move the rear wheel, move it forward. Get your chain on nice and tight. Don’t worry about getting the perfect ½” play, because ten seconds after you ride it, it’s gonna loosen up, and after a week when your sprocket’s teeth wear in, you’ll get an extra inch. Use washers on the inside of the wheel if you have to space it out, but align it as good as you possibly can with the engine.

once that’s on, put your pedal chain on. If it’s really loose, you might be able to remove links from it to make it fit. If it’s still too loose, or now it’s too tight, switch out the rear cog. A one tooth difference will change your chain about an inch. Keep messing with it till you get it right. If it rubs the frame or the tire a little, oh well. Don’t worry about it. The chain jumps all over the place, so a little slap won’t hurt. If it rubs a LOT, then worry. You don’t want to cut your chain-stay in half. Go here (Bicycle Frame Spacing )to learn how to spread out your frame.
and a chain tensioner should NEVER be used as a chain aligner. Chains are designed to roll in one direction, not turn corners sideways. If that’s your solution to chain-misalignment, you’re doing it wrong.

if you absolutely must use it, weld it on, or make a really strong bracket. Some people say drill a hole in the frame, or screw it in, but I’m totally against that. The chain stays are too thin, too small in diameter, and too important to be drilling holes in. plus, I like jumping my bike over railroad tracks and speed bumps at 30mph, and I don’t want to die when the rear half of my bike is 20 feet behind me.

after a week or so, when your sprocket and chain break in, you can move the rear wheel back to tighten the engine chain, and drop a tooth on your rear cog. should line right up.

if you've got a single speed cruiser, you can change out the front sprockets, too.

i've run bikes with and without tensioners, and it's waaaay smoother without one. it's quieter, it seems faster (that's probably psychological) and it's one less piece to worry about.

now, when you’re doing your pre-ride check, don’t just look at your muffler to make sure it’s still there. Check for loose wheels, broken bolts, crooked valve stems on your tubes that will get cut off by your rims, cracked forks, etc… I’d rather lose my muffler than my front wheel.

lastly, (for now,) if your bike starts acting funny all of a sudden, stop and check it immediately. My first build, I hammered on a 1950’s piece of crap frame for a month, and then it started vibrating really bad. Turns out, I broke my frame. If I hadn’t noticed right away, I’d be typing this with my teeth…

oh, one more thing. if you're the guy with the rat bike from goldenwest swap meet, p.m. me, and i'll help you out. i really liked lawn-darts.CPSC Bans Lawn Darts

wow. that was longer than i thought...

I agree with most of what you said except for your views on the tensioner. Properly installed and aligned they do not cause problems, do not make noise and do not rob power. The biggest problem with the kit supplied or any chain tensioner is because of improper installation resulting in chain misalignment and several other woes.
Chains wear, so do sprockets and after a period of time there needs to be some method of adjusting for that instead of shortening the chain or moving the rear wheel. Look at any industrial chain drive application and you'll see a method of maintaining proper chain tension, either idler pullys, guides or sprockets, springs or slotted brackets. The reason for them is to keep the chain aligned and tensioned without the need to reposition critical components such as conveyor rollers, platform guides etc. The other function of the tensioner, in the case of our bikes, is to assist in guiding the chain onto the rear sprocket. A loose chain when subjected to side, lateral, forces can sway and that, under the right conditions can cause a chain to derail the rear sprocket with the associated, sometimes disastrous results. Your concern for compromising the integrity of the chainstay by drilling into it is not supported by the successful results of a large number of builders. I have one bike with 1587 miles on the odometer and that's over Colorado streets and roads that are notorious for their rough surfaces. The chainstay was drilled and a 10/32 bolt run through it and the tensioner bracket before the engine was ever fired for the first time. The frame has not failed nor upon inspection of the drilled area is there any evidence of stress cracking or metal fatigue.
As I said, for the most part I totally agree with your observations regarding proper set up and maintenance of a motorized bicycle. Thank you for the in depth information and I'm sure you and I will generate a lot of controversy with our views on the tensioner verses no tensioner opinions. It might be interesting...
Tom

__________________
Age and Treachery Will Always Triumph
Over Youth and Skill

I was thinking the same as 2door. I also agree with it all accept the tensioner bit.

Well said Bairdco, you forgot to mention gas caps belong on gas tanks not on the top of a pump back at the filling station.

My original gas cap vibrated off last year. Retraced my route a dozen times but could not find it.
It's a Homelite leaf blower motor with the plastic fuel tank and plastic cap. Luckily, I bought a new one from the John Deere shop, I think.
I used the smallest drill bit I own to make a hole in the bottom/side of the cap. Some Spiderwire kevlar fishing string goes around the filler neck of the tank and the cap. It's lasted 2 years and about 4000 miles so far.

bairdco - ya forgot the JBweld fanatics lol

i knew the chain tensioner would get to you, 2door. you're a big advocate for the drill method. for me, though, i just wouldn't do it. but like i said, i routinely jump my bike off curbs, driveways, whatever, and i like to just beat the heck out of it. i don't want to drill a hole anywhere on my bike, especially in a place that bears a heavy load.

for normal cruising, it's probably fine.

my other issue with them, is it's just so much smoother without one, once everything's working properly. since the stock one's not spring loaded, all it does is take up the slack. if it's not moving with the chain as it bounces, it's technically not even a "tensioner." it's more of a guide.

and i spend a lot of time making sure i don't need an extra "guide," with frame spacing, wheel spacing, offsets, etc.

granted, it is a simple way to put a bike together, but i still think it's an extra part, with a high potential for failure. and cataclysmic failure, at that.

if it was just something that fell off when it broke, i wouldn't be so passionate about it.

but since i'm usually balling the jack down hills at 40+, the thought of a hunk of metal going through my spokes is not one i want to have.

plus, it looks so much nicer without one.

i'm surprised that with all the cool aftermarket parts people are making for these bikes, no one's come out with an alternative, functional tensioner.

now that i've fully stated my opinion, i'm willing to drop the whole subject.

Bairdco, I used a piece of inner tube between my motor mounts and frame, not to kill vibration but so I didn't mar up the frame, so far I've had to tighten the bolts (after break-in) once in about 1000 miles. The chain tensioner thing I can see where you are coming from, I do use a tensioner but I only use the one that mounts with 4 bolts, I have seen the 2 bolt ones and frankly they seem scary to me. Its good to see your looking out for your fellow rider, thanks for the post

Of the stock tensioners - I do prefer the four bolt variant, tho I must mention that those don't usually come with a bearing in the roller. It's a lil thing, but I did swap rollers from a 2 bolt one I had kickin' around.

More info on tensioners ifn ya wants;
Chain tensioner "suggestions"