I recently had a rear flat tire and replaced the inner tube. I was
pleasantly surprised at how easy it was to remove the rear tire!
However, I think I left too much slack in the chain. Today I noticed a
lurch in first gear several times on my way home from work. From the
sound and jerk, I thought the chain was slipping. Upon closer
inspection at home, I have six broken teeth on the rear sprocket. When
looking for a replacement sprocket, all I can find is a complete
sprocket and chain set or a variable tooth rear sprocket. I am leaning
toward the variable rear sprocket with a few fewer teeth. I think the
current sprocket has 38. I ride up and down a mountain (1500 ft.)
everyday and could use a little more low end in first and fourth
gears. Anyone have any suggestions? It looks like the complete drive
train overhaul is a little more serious than merely replacing the rear
sprocket. How can I be sure the chain problem is due to my rear tire
removal and replacement rather than wear?
Steve Smith wrote:
> I have six broken teeth on the rear sprocket. When
> looking for a replacement sprocket, all I can find is a complete
> sprocket and chain set or a variable tooth rear sprocket.
What is a variable tooth sprocket?
> I am leaning
> toward the variable rear sprocket with a few fewer teeth. I think the
> current sprocket has 38. I ride up and down a mountain (1500 ft.)
> everyday and could use a little more low end in first and fourth
If you want more low end grunt, you need more teeth on the rear, not
fewer. This will increase revs and reduce top speed.
> How can I be sure the chain problem is due to my rear tire
> removal and replacement rather than wear?
Six broken teeth is pretty extreme, not what would be considered normal
wear. Hard to imagine actually. Something is badly misaligned, or way
too slack (or both). Are you riding in gravel and getting stones chucked
up into the chain/sprocket area?
>How can I be sure the chain problem is due to my rear tire
>removal and replacement rather than wear?
You have been BAD! Now you must pay! If I may quote myself (for a
change - hah!):
It is necessary to check the chain's condition regularly. As a chain
wears, it "stretches," getting longer from end to end due to the
holes in the plates, in which the rollers run, elongating. This
"stretch" is also evidenced from center to center of each roller, and
it will soon exceed the c-to-c tolerance level for the sprockets,
with the rollers beginning to ride up on the sprocket teeth. This
will result in an extreme steepening of the sprocket wear curve,
resulting in hooked teeth and trashing of the sprockets. Since a pair
of sprockets and the work required to change them is in the order of
tens of times the value of a new chain, it is only good insurance to
change chains in a timely fashion. Your chain should not require
replacement for awhile - a number of adjustments will be required
first, but when you run out of adjustment, replace it for sure -
don't be tempted to take out a link, or to take out two and replace
them with a "monkey link" - a link and a half. Replace the chain! In
fact, this should be done BEFORE you run completely out of
adjustment. More on this later.
A good way to check a chain for wear is simply to pull it away from
the rear of the rear sprocket. A worn chain will pull a long way out,
and observation of the surrounding rollers will show them to be
pulling up out of the gullets towards the tips of the sprocket teeth.
It takes an "eye," like most things, to decide when to change the
chain with this method, but if it can be pulled much more than an
inch or so back, when the chain is loose as described below, then
it's time to start thinking about changing the chain. If in doubt,
buy and install an new chain, and check it immediately after
installation, and every 200 miles/ 300 km after that, and you'll
learn what you need to know. If there's not much difference from your
original chain, keep it for a spare, and put it on when your new one
gets bad. Simple but important.
Worst part is, if you've lost a half-dozen rear sprocket teeth, your
front sprocket will be trashed, also. I wouldn't try to fake it;
you'll need both sprockets and I'd buy a couple of new chains - I
always keep a spare on hand so I won't ever be tempted to run a worn
chain for too far (it wears out the sprockets if you do, ya know!)
As for a gearing change, you can just order a 17T front sprocket and
use a regular rear sprocket. 17 is low, 19 is high for regular
riding. For trials work, they supplied them down to 12 I think, 14
for sure. But top speed is in the 30s that way. (mph), so I wouldn't
go lower than 17 for road work.
Changing the front sprocket is a bear. Don't do it without a good
manual on hand.
How can I be sure the chain problem is due to my rear tire
> removal and replacement rather than wear?
With six missing teeth you've probably got one of those unique
quality controlled sprockets where they've forgotten to remove all
the sand during the manufacturing process. Unfortunately it leaves
the inside of the sprocket looking like an Aero bar; clean up the gap
left by the miising teeth and check.
I seem to recall the sprocket conversion only allows standard or more
teeth than standard so it can only be used to lower the gearing -
which from your message is what you want.
You then have the option of using different (= better?) material/s
for the replacement sprocket should you wish to go down that road.
If your worried about any current alignment problems, a quick check
is with the rear wheel clear of the ground, spin it backwards. Then
check to see if you have an equal gap between either side of the
sprocket teeth and the inside of the chain plates.
> I seem to recall the sprocket conversion only allows standard or more
> teeth than standard so it can only be used to lower the gearing -
> which from your message is what you want.
Yes, the standard rear sprocket is 38 teeth. The conversion allows 38 to 50
teeth, and thus as Ric says you can only gear down with this feature. The
rear conversion option is expensive, about $200 for the full setup (hub and
sprocket), and about $70 for each additional sprocket you buy.
FWIW, you can also get lower gearing by changing out the front
(countershaft) sprocket with a -smaller- one, or higher gearing by changing
the countershaft to a larger sprocket. Stock is 17T for the 500, and
sprockets from 16T to 21T are available. Each tooth on the countershaft
gains you about 6% higher/lower gearing. (+1t = 6% higher, -1t = 6% lower.)
This is the traditional route we've all followed, since a changeable rear
has never been available before this year. Many of us have gone to an 18t
for general riding; side hacks often use 16t for better power.
I replaced the rear sprocket with a 42 tooth sprocket. Of course the
chain barely fit. I had to remove the chain adjustment cams to get the
wheel to its most extreme forward position. Of course the cams are
still needed in the assembly to provide the correct spacing so the
axle nuts do not bottom out on the threads before the hub is tight
against the frame.
I went on the test drive. I realized too late that I needed to adjust
the brakes. At least I had a front brake.
Once back at my garage I adjusted the brake ---- incorrectly. Instead
of using the wingnut, for some reason I loosened, rotated and re-
tightned the brake pedal arm. The brakes now at least slow the bike
down but really won't stop it in any meaningful way.
Tomorrow I'll undo my erroneous adjustment and try using the wingnut
adjuster as instructed in Snidal's manual. At least the gearing is
noticeably better on the hilly terrain here in East Tennessee.
It’s important to take proper care of your teeth. I am searching for an expert dentist as had broken one of my teeth when I fell from stairs last week. Got to know about a dentist Redondo Beach and going to take appointment from him.