A long shot: Bicycles that don’t require chain tensioners

[INTP_ty]

Taking a long shot, but does anyone know A bike off hand where no tensioners is needed? *Depending upon the down tube, I’ll order either style engine (wide front mouthed Zeda or regular PK-80 so I don’t have to use the flat plate/U-bolt adapter.

~44T

 

[CrazyDan]

Any bike that fits your engine with a jackshaft to the right side, since it uses the original chainline.

 

[gary55]

Multi speed bikes without J shafts and with deraieluers are harder to maintain proper tension without a tensioner due to the inability to move the back tire for or aft.

 

[FurryOnTheInside]

All the bike frames I know of with a derailleur mount (to tension the pedal chain) and rear facing horizontal slotted dropouts that are made to have the option of being used as single speed or geared bikes are 24" or 26" wheel dirt jump bikes, therefore way too small (low top tube) to fit the engine.

But you might be able to use/make a tensioner like the stock one from the kit, or make something like a derailleur hanger for a single speed tensioner and use it on the pedal chain of a single speed beach cruiser that has rear facing horizontal slotted dropouts to tension the motor chain.

One or other of the chains really needs a tensioner (or derailleur) because for the wheel to be straight in the frame and both chains to be at the correct tension and remain that way is incredibly unlikely.


Beach cruisers more frequently have no need to lift the chain over the chain stay.
Beach cruisers have more parallel chain stays: the U shape chainstays when you view the frame from below/above as opposed to V or some weird trumpet shape as on many other styles of frame where the tensioner serves a second purpose: to lift the chain over the chain stay.


But what about the gas tank frames? Don't some of those have the horizontal slotted dropouts, derailleur mount, and parallel chain stays?

 

[CrazyDan]

One or other of the chains really needs a tensioner (or derailleur) because for the wheel to be straight in the frame and both chains to be at the correct tension and remain that way is incredibly unlikely.

For both chains to be perfect without a tensioner on one side or the other is winning the lottery.

But what about the gas tank frames? Don't some of those have the horizontal slotted dropouts, derailleur mount, and parallel chain stays?

There were quite a few at the races with the gas tank frames with no derailleurs on the left side, but used one on the right side. Can't get away from it if you have 2 chains going to the rear wheel.

 

[Spare_Parts]

My bike has no tensioners. Last bike had one on the pedal side.

 

[FurryOnTheInside]

My bike has no tensioners. Last bike had one on the pedal side.

How? Do you just run the pedal chain a bit loose?

Or an eccentric bottom bracket would do it I suppose, but that's probably overkill lol. Cool though.

 

[inspectorcritic]

You could just accurately measure the chain cut it, you might get it so tight might pull out of the brackets or even if you move it 3/8" forward or backward in bracket is enough tensioner but I worry of it coming all the way out.
Then keep in mind your chain is going to stretch in the next few months and the following year.
However you can reduce the stretch by going to a 420 chain there tuff next chain I get is going to be a 420.

 

[Spare_Parts]

How? Do you just run the pedal chain a bit loose?

Or an eccentric bottom bracket would do it I suppose, but that's probably overkill lol. Cool though.

Half link and adjusting the engine mounting. Going to add a jockey wheel because the chain sometimes gets a bad shake. Guess it's basically a tensioner lol.

 

[CrazyDan]

Half link and adjusting the engine mounting. Going to add a jockey wheel because the chain sometimes gets a bad shake. Guess it's basically a tensioner lol.

Yeah, I noticed long chain runs without an idler or tensioner wheel tend to get a harmonic vibration at certain rpms, causing the chain to whip the tire.
That gave me problems when I was running a derailleur with my shift kit, would make it shift back and forth if I tried to use 6th or 7th gear. No amount of adjustment helped, probably need to use semi-high end shift sets to end those problems.

You could just accurately measure the chain cut it, you might get it so tight might pull out of the brackets or even if you move it 3/8" forward or backward in bracket is enough tensioner but I worry of it coming all the way out.
Then keep in mind your chain is going to stretch in the next few months and the following year.
However you can reduce the stretch by going to a 420 chain there tuff next chain I get is going to be a 420.

Going with heavier chain may solve some issues, but then you end up with more powertrain losses. I use kmc 510 from my chainring to the back wheel (slightly skinnier than 410) and kmc k710 from my tc to jackshaft and jackshaft to chainring. It refused to stretch when it tried to derail, so it shattered my sealed bearing the jackshaft rides in on the right side. Chain is no longer the weak point (might be cheaper to keep it the weakest part of the drivetrain...).