transmission drag, chain tensioner angle

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Jul 18, 2018
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#1
t belt creates a lot of resistance, no matter whether it is loose or tight; i think it wont even go downhill, pedalling is not an option at all. also in such mode transmission parts would wear quickly. when bike is going under inertia bottom line of chain is stretched, putting strain on the plastic roller of tensioner, which is only to give chain slight support when top is stretched. it seems that motored bike could only be used with freehub on the left side. what is lifespan of transmission if used without freehub? how hard does bike move?

chain tensioner roller is out alignment with chain line about 30 degrees. how do you solve this?
 

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#3
What he said. Bend the bracket til it lines up.

A lot of the resistance you feel is just cold weather. Chain lube is thick, and there's a hundred joints in the chain. It'll free up a lot in warm weather. Also, how tight is your chain? Loosen up the chain tension and see if things free up. You should have about a half inch of slack in the top run.

If the resistance is in your belt drive, give it a once-over to make sure everything's running nice and free. Some resistance is normal, but you should be able to push the bike easily, with just a little resistance. If you can't pedal it, something's binding. Start with the chain and work your way forward.
 
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#4
i dont know how people ride on it 60 kmh, i would say 15 is a max, so you can fall off bike and hope you are safe.

there's no way to use it without chain tensioner? this part is just something; chinese engineers could have put just a tiny bit of effort in designing it. im scared to think what happens if chain comes off or something goes wrong with one of the bolts...

i dont want to bend; im trying to wrap copper wire and clamp between those plates; is it a bad idea?
 
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#6
this thing just rotates no matter how much you tighten it; with too much force there could be damage to frame or bolts; it is more or less firm only in one position - but thats not in alignment with chain even in this plane, not talking about the other; did the one who designed it have in mind possibility of adjustment? at least 4 bolts are needed. did they even test before producing in million numbers?

if there were 4 bolts there would be a way to put something under it and adjust angle, plus secure clamping.
 
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#8
as i see this chain is very likely to coming off, a small misalignment of tensioner roller is enough, or for no reason. when it does at speed what will happen? engine cant be stopped instantly, so for some time it will continue moving chain, meanwhile the rest can get tangled and lock the wheel. have you experienced this? would freewheel help? do any of you use hub with freewheel?
on ordinary bicycle no matter what happens with chain it does not affect you safety at all.
 

CrazyDan

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#9
If you are scared of the chain tensioner then get a shift kit. the chain wants to run straight but most chainstays are diagonal. The best remedy has already been mentioned, I like to use an adjustable crescent wrench to twist the tensioner to allow for a straight chain run.
 
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#10
the weak point of this chain transmission is this: if for some reason it decides to get on top of teeth, all system becomes in big tension: drive sprocket, tensioner, rear sprocket. it cant come off yet, because of not enough room;so it will break (bend) the weakest link - drive axle or tensioner roller (axle). at this moment wheel can be blocked or if chain comes off, later when wrapped around axle. if it is made intentionally loose (to allow it come off if it decides so, without damaging parts) it may increase chances of coming off.
freewheel can help in that when you are coasting you can feel safe for the chain because it is not moving.
is it a general flaw of the system with fixed tensioner? how is it on other types of machines (motocycle, ect)?
have you experienced chain coming off and what happened?
 

gary55

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#13
Well I guess you deleted your previous post, so here's the deal. You have to be smarter than a crooked line. Get this tensioner pulley lined up properly and it will be fine. Or don't. You ask for advice and are given good advice, but you refuse to listen to people who have tackled this problem with success hundreds of times. Get a grip and get after it. No rocket science here. It's a f#%king chain.
 
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#15
im afraid of design decisions that put life of rider in danger. sprockets that are fixed to hub or spokes are produced on mass scale (so i assumed they must be safe). have there been accidents? if wheel gets locked up when coasting downhill i think it is not difficult to see what would happen. in my opinion it should be prohibited to use this system without freewheel; or i dont understand something? am i exhaggerating its danger?

whats needed is a system that on right side of you bicycle - spring tensioner with limits and freewheel - perfectly safe and secure. if due to geometry it is not possible to make a spring tensioner, the fixed one can still be used; with freewheel its disadvantage is that in case of lock up engine and transmission parts will be damaged (with spring tensioner chain would go where it needs to without breaking transmission). on a single speed bicycle if chain is stuck you feel it and stop applying force, whereas here the time before you switch off engine would be enough for it to grind transmission or itself.

i found only one freewheel hub (the one with useless drum brake); by look it has bigger diameter hole than fixed sprockets (they dont write the most important data, like widths, diameters, number of spokes, ect, you should guess it by looks) so my 56t sprocket would not fit there; and of course there's no such sprocket for that hub. why cant they make freewheel hub with standard mounting patterns?
 
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#16
WP_20181203_08_52_39_Pro.jpg

in this example chain came off and very naturally locked itself
WP_20181203_08_54_38_Pro.jpg

how much slack should there be? here it would be enough for chain to come off without damaging parts, but it can be a little loose at the bottom of the sprocket.
WP_20181203_09_23_00_Pro.jpg

if this happens, even with the most slack it already starts breaking parts; with less slack it will be worse.
 
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LR Jerry

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#18
I ran into a similar problem on a build with my late brother. The way we got the correct angle alignment was to use two adjustable wrenches to twist the tensioner to the correct angle.
 

junglepig

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#19
On my cruiser I had to bend the tensioner arm a little to get good alignment from front sprocket to tensioner to rear sprocket.
I have not ever had the chain come off. I do have to adjust the tensioner about once/week. I expect that to become less frequent as the chain finishes stretching and wearing in. But having correct alignment to begin with is critical.
I will eventually get or make a good motor mounted chain tensioner, but for now, my is working fine.
I did change the hardware when I originally mounted it so I could torque the clamp down tight enough to hold it fast. That has not been an issue.
 

gary55

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#20
Twisting it also helps the master link go be the outer stop on the tensioner without that clunk clunk clunk every time it goes by.
 

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