Fixed or single without chain tensioning

[Tobias]

Does anyone run a fixed or single without chain adjustment? If so, how many miles do you normally go before chain stretch or sprocket wear causes problems?

Please note I’m familiar with many of the available options for installing some form of chain tensioning, but that’s not the question I’m asking.

Assuming one starts with a perfect set up, how long will it stay that way? Any experience?

[Fixed]

bro i have tried them and they aren't needed for my use .. I find if i wipe my chain after i get home at night and lube reg i'm good to go ..keep your chain clean
when all the stuff starts chattering it's tellin me it 's time imho
cheers bro i have never had the chain fall off yet they don't have be (the chain) doesn't need to be real tight imho

[Grant McLean]

how many miles do you normally go before chain stretch or sprocket wear causes problems?



Depends on the conditions and the components.

3/32" or 1/8" ? The wider stuff doesn't wear as quickly.
In my experience, the rings, chain, and cog can be totally wasted
and still not skip. The wear of the chain will become longer, so
you'll need to move the wheel back.

(it doesn't "stretch", but you knew that...)

-g

[markie]

Do you mean tensioner, like a derailleur kind of device or tensioner like tugnut?

Because you cannot run fixed gear with a chain tensioner that is like a derailleur.

I find I can leave my bikes weeks of riding most days and still not have to re-tension the chain.

[Tobias]

bro i have tried them and they aren't needed for my use .. I find if i wipe my chain after i get home at night and lube reg i'm good to go ..keep your chain clean
when all the stuff starts chattering it's tellin me it 's time imho
cheers bro i have never had the chain fall off yet they don't have be (the chain) doesn't need to be real tight imhoFixed, are you using a standard frame with vertical dropouts? In other words, no adjustment.

[Tobias]

The wear of the chain will become longer, so
you'll need to move the wheel back.

(it doesn't "stretch", but you knew that...)

-g
Correct Grant -- no wheel movement with vertical dropouts (mostly vertical).

[Tobias]

Do you mean tensioner, like a derailleur kind of device or tensioner like tugnut?
I mean no tensioner at all. I'm told it's possible to fiddle with sprocket sizes until one gets it right. Or do the math in advance and get it right from the start? Don't know how accurate it can be estimated, but would give it a try first.

[Grant McLean]

I mean no tensioner at all. I'm told it's possible to fiddle with sprocket sizes until one gets it right. Or do the math in advance and get it right from the start? Don't know how accurate it can be estimated, but would give it a try first.

You can also use a 1/2 link to make the chain shorter.

But a fixed gear won't work with a spring loaded tensioner,
that's only for a single speed freewheel.

Other options for vertical drop outs is a hub like the white industries eno.

-g

[markie]

So what you have is a frame with vertical droputs that you want to run a SS with a magic gear.

There are several tricks for doing this most can be found with sheldon brown.

These include, use of a half link. Filing a small amount from the dropouts, filing a small amount from the axle.

These are really bodges. Probably better to get the proper frame to start with or get a white industries Eno eccentric hub.

I have a mountain bike that I run with a magic gear and it is somewhat frustrating being stuck with the one ratio.

[Tobias]

So what you have is a frame with vertical droputs that you want to run a SS with a magic gear.Yes


I have a mountain bike that I run with a magic gear and it is somewhat frustrating being stuck with the one ratio.
Thanks markie; exactly what I was looking for. First, how often do you have to replace the drivetrain due to chain stretch or other wear? Can you get say 1000 miles out of it before doing major work? How about 2,000 miles? I know MTB use will be much worse than road.

Second, why are you stuck with one ratio? Can't you replace chainring/sprockets to create other magic combinations?

[Ti Designs]

OK, one last post and I'm outta here...

Here goes..

Sheldon Brown knows all.

[markie]

I filed the droputs on my MTB a little and one chain has lasted a lot of miles.

Reduction by two teeth should give the same tension if you remove one chain link, but due to the wrap of the chain that does not work. It is called magic for a reason.

Again, Sheldon Brown knows all.

[Fixed]

Fixed, are you using a standard frame with vertical dropouts? In other words, no adjustment.
my bike has track forks i thought he was talking tug nut things that keep the back wheel from moving .sorry
cheers :beer:

[Tobias]

Reduction by two teeth should give the same tension if you remove one chain link, but due to the wrap of the chain that does not work. It is called magic for a reason.
My understanding is that it takes four teeth total to make a link's worth of difference and two teeth to make a 1/2-link.

I haven't tried it, but if 42/21 was a magic combination, then 46/21 should also be very close with an extra inch of chain. 44/21 should also be close with 1/2-link. Seems there should be lots of additional possibilities if one worked.

Even with the same chain length can't you keep the same number of teeth; going from 42/21 to 44/19 or 46/17 etc....? Don't know how much chain angles change things.

[markie]

It might work, but it relies on finding one good ratio to start with.

My magic gear is on a MTB and there are not many different middle ring sizes that will work.

Life is much easier with horizontal dropouts/track ends.

[Fixed]

OK, one last post and I'm outta here...

Here goes..

Sheldon Brown knows all.
he wrote the bible
cheers

[RPS]

Estimating available ratios that will work with limited chain-length increments for any given chainstay length is a very interesting problem – unless I screwed up the analysis along the way.

Given a frame with vertical dropouts that has a fixed chainstay length; available solutions seem to be dependent on differences in pitch diameters of the chainring versus rear cog. As long as the difference in pitch is held constant, alternate ratios can be found easily.

I worked out the numbers for my Calfee and it turns out that the following combinations should work equally (provided chainstay length is exactly as specified):

40/12; 42/14; 44/16; 46/18; etc…..

In theory I should be able to vary the gear-inches from about 68 to 88 by picking one of these combinations. For that particular frame the chainring must be 28 teeth larger than the cog for it to work (with practical sizes – the next increment is 46 teeth difference so a 58/12 should also work). A ½-link would allow me to add more options but requires the same difference of 28 teeth.

If my math is right it’s more about finding the correct chainring-to-cog teeth increment for a given frame’s chainstay length than finding a magic ratio.

Does this make sense?