fixed wheel conversion - newbie question

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In article <[email hidden]>,

miles said:

Hi,

I've just converted an old racer of mine to a fixed gear. Having read
all the guides on how to set it up, there's one thing that is confusing
me - apologies in advance if this is an obvious question but I've spent
quite a while looking...

When it comes to adjusting the chain tension, what is binding? How can
I tell when the chain is binding?

The chain will get so tight that it is difficult to turn the
crank. Depending on how eccentric your gears/cog are you may
or may not experience this problem.

At the moment, I have adjusted it so

Quoted message said:

that, with the bike in a stand, I can push the pedals round in either
direction with my hand and move the wheel - any slacker, and I could
push the pedals slightly before the wheel moved (as the chain takes up
the slack).

Does that sound right or hopeleslly off the mark?!

_ Sounds way too slack to me. Many bad things happen when the
chain comes off on a fixed gear, it's much better to err on
the side of too tight rather than too loose.

_ If the chain is not binding then it's not too tight IMHO.
I've got thousands of KM's on a fixed gear with the chain as
tight as I can get it. The chain can move up and down about
1/2 an inch, but it takes force to do it.

_ Booker C. Bense

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miles said:

Hi,

I've just converted an old racer of mine to a fixed gear. Having read
all the guides on how to set it up, there's one thing that is confusing
me - apologies in advance if this is an obvious question but I've spent
quite a while looking...

When it comes to adjusting the chain tension, what is binding?

The cogs and their bearings are never perfectly, exactly round and/or
concentric. If you adjust the distance so that at a particular
orientation of the cogs where they are closest together there is zero
(or very little) chain slack, at another orientation where the cogs
are slightly farther apart there will not be any slack; indeed the
chain may be under some amount of tension. This condition is what is
called "binding".

Quoted message said:

How can
I tell when the chain is binding?

Adjust the distance so that in all orientations there is at least a
small amount of slack. I tend to let a greased finger slide on the
bottom run of the chain, pressing downwards while turning the pedals
(the cycle being held off the ground in a stand or a set of hooks or
similar). Feel how much downwards motion you have with the finger,
and feel the resistance to turning with the pedaling hand. No motion
and more resistance? Binding.

Quoted message said:

On 25 Sep 2006 09:47:11 -0700, "miles" <[email hidden]> wrote:

Adjust the distance so that in all orientations there is at least a
small amount of slack.

There's no need for any chain slack at "turning it on the workstand"
loads; a chain that's tight on the workstand will have plenty of slack
on the unloaded (usually bottom) run as soon as you actually ride it
and put some significant load on the pedals. Load this image
http://brightonmitre.com/gallery/gal/Miscellany/Reading.jpg and put a
straight edge against the bottom chain run; that chain was tight on
the workstand both before and after being exposed to my modest
starting effort.

So, find the point in the crank rotation corresponding to maximum
tension, and pull the wheel back in the dropouts as hard as you like
before tightening your track nuts.

You can overtension the chain if you use chain tugs, so get the wheel
in right with the tracknuts tightened and the chaintugs clear of the
dropout before adjusting the chaintug screws so the relevant parts
just touch the droupout; their purpose is to hold the wheel in the
predetermined right place, not to pull it into place using the large
mechanical advantage of what is in effect a screw jack.

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

miles said:

Hi,

I've just converted an old racer of mine to a fixed gear. Having read
all the guides on how to set it up, there's one thing that is confusing
me - apologies in advance if this is an obvious question but I've spent
quite a while looking...

When it comes to adjusting the chain tension, what is binding? How can
I tell when the chain is binding?

Neither cogs nor chainrings are perfect circles, or maybe not perfectly
centered. So, if the chain is quite tight, you may find that at some
positions it becomes so tight that it slows down the spinning of the
wheel/cranks if you spin them with the wheel off the ground. That would
be binding.

At the moment, I have adjusted it so

Quoted message said:

that, with the bike in a stand, I can push the pedals round in either
direction with my hand and move the wheel - any slacker, and I could
push the pedals slightly before the wheel moved (as the chain takes up
the slack).

Try it tighter, and you will see what is meant by binding.

--

David L. Johnson

__o | Some people used to claim that, if enough monkeys sat in front
_`\(,_ | of enough typewriters and typed long enough, eventually one of
(_)/ (_) | them would reproduce the collected works of Shakespeare. The
internet has proven this not to be the case.

Booker C. Bense said:

At the moment, I have adjusted it so

Quoted message said:

that, with the bike in a stand, I can push the pedals round in either
direction with my hand and move the wheel - any slacker, and I could
push the pedals slightly before the wheel moved (as the chain takes up
the slack).

Does that sound right or hopeleslly off the mark?!

_ Sounds way too slack to me.

Huh? No slack is too slack?

Quoted message said:

Many bad things happen when the
chain comes off on a fixed gear, it's much better to err on
the side of too tight rather than too loose.

Well, that is debatable. It doesn't sound too loose to me, according to
the OP's description.

Quoted message said:

_ If the chain is not binding then it's not too tight IMHO.
I've got thousands of KM's on a fixed gear with the chain as
tight as I can get it. The chain can move up and down about
1/2 an inch, but it takes force to do it.

That is pretty tight.

--

David L. Johnson

__o | Become MicroSoft-free forever. Ask me how.
_`\(,_ |
(_)/ (_) |

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In article <[email hidden]>,

David L. Johnson said:

Booker C. Bense said:

At the moment, I have adjusted it so

Quoted message said:

that, with the bike in a stand, I can push the pedals round in either
direction with my hand and move the wheel - any slacker, and I could
push the pedals slightly before the wheel moved (as the chain takes up
the slack).

Does that sound right or hopeleslly off the mark?!

_ Sounds way too slack to me.

Huh? No slack is too slack?

_ I guess I misread the original description. I still think it's
too loose. On the bike stand there should be some tension in the
chain.

Quoted message said:

Quoted message said:

Many bad things happen when the
chain comes off on a fixed gear, it's much better to err on
the side of too tight rather than too loose.

Well, that is debatable. It doesn't sound too loose to me, according to
the OP's description.

Quoted message said:

_ If the chain is not binding then it's not too tight IMHO.
I've got thousands of KM's on a fixed gear with the chain as
tight as I can get it. The chain can move up and down about
1/2 an inch, but it takes force to do it.

That is pretty tight.

Even at that tight, you can see the bottom run going slightly slack when
pedaling hard. It seems to me that's what you want to minimize as
much as possible. I get reasonable mileage on chains and don't
see any cog wear yet. I do use large front/back(50/18) cogs so the forces
there are smaller than the would be otherwise. It might just be
overkill on my part, but so far I don't see any reason not to run
them this tight.

With a freewheel, I could see some justification for not running
the chain this tight. But I don't see any reason not to run the
chain relatively tight on a fixed gear. I've been wrong before
though, so educate me...

_ Booker C. Bense

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The chain should be tight enough to not flop around and derail, and
loose enough that it doesn't bind. If you're obsessing over chain
tightness, you should get out and ride more.

Booker C. Bense said:

With a freewheel, I could see some justification for not running
the chain this tight. But I don't see any reason not to run the
chain relatively tight on a fixed gear. I've been wrong before
though, so educate me...

My only criteria here are that the wheel should not bind, which would slow
you down a little and might stress the chain, and that the chain should
not fall off. Losing a chain, as you mentioned, in a fixed gear is
dangerous. But between these two extremes, I don't see that one position
has any merit over another.

--

David L. Johnson

__o | Enron's slogan: Respect, Communication, Integrity, and
_`\(,_ | Excellence.
(_)/ (_) |

David L. Johnson said:

Booker C. Bense said:

With a freewheel, I could see some justification for not running
the chain this tight. But I don't see any reason not to run the
chain relatively tight on a fixed gear. I've been wrong before
though, so educate me...

My only criteria here are that the wheel should not bind, which would slow
you down a little and might stress the chain, and that the chain should
not fall off. Losing a chain, as you mentioned, in a fixed gear is
dangerous. But between these two extremes, I don't see that one position
has any merit over another.

A chain too tight will also cause premature wear on the sprockets (ask
me how I know 🙂. And it can't be good for the wheel or bottom bracket
bearings, either.

--
Dave
dvt at psu dot edu

Everyone confesses that exertion which brings out all the powers of body
and mind is the best thing for us; but most people do all they can to
get rid of it, and as a general rule nobody does much more than
circumstances drive them to do. -Harriet Beecher Stowe, abolitionist and
novelist (1811-1896)

And purely as a safety reminder, from another fixed newbie, be VERY careful with fingers around adjusting chains on a fixed. See Sheldon for a better description than I can give, providing you're not too squemish about the pictures.

Mal