Ratio and Your Wheel
Ratio is one of those terms that is often bandied about in
wheel advertisements and
spinning articles and not
so often defined. In essence:
for every complete revolution of the drive wheel (that’s
the big one), the flyer turns
a certain number of times.
That figure is the ratio, and it is expressed as X:1 (the
flyer turns X times for a single revolution of the drive wheel);
for example, 4:1 (the flyer turns four times for a single
revolution of the drive wheel) or 18.5:1 (the flyer turns
eighteen and a half times for a single revolution of the drive
wheel). Occasionally, the numbers are flipped (for example,
1:4), but the number one always refers to the drive wheel.
Often, the whorl that determines the ratio is a separate
piece [see above] with
two grooves of slightly different
diameter. Sometimes (as on
most Louet wheels), the bobbin
groove itself determines
the ratio [see below, photo
courtesy Louet]
The relationship between twists per inch and ratio depends on how much fiber is drafted
for every full revolution
of the drive wheel. Theoretically, if you drafted exactly
an inch of fiber for every turn of the drive wheel, you would
know that if you were using a whorl with a 15:1 ratio, you’d
insert 15 twists in every
inch of yarn. But few of
us draft and treadle with such precision, so you’re
looking at ball park estimates here.

Think: a lower ratio
will give you less twist
per inch and a higher
one will give you more. 



Think: a lower ratio will
give you less twist per inch and a higher one will give you
more. In general, slow ratios would range from perhaps 4:1
to 8:1; medium from about 9:1 to 12:1; and fast from 13:1
and up, with anything above 20:1 being very fast.
You should be able to consult
your owner’s manual
to find out what ratios
are standard issue for your
wheel. Usually, faster and
slower whorls are available
for purchase separately.
If you bought your wheel
used, try googling
the maker's website  many
wheel manufacturers have
PDF versions of their manuals
available for download. But
what if you have a handful
of whorls and can’t
remember which is which?
Or an antique wheel? You
can get a decent estimate
of the ratio by marking the
drive band and one side of
the flyer with a little piece
of yarn and then turning
the drive wheel once very
slowly, while counting how
many times the flyer rotates.
Because the exact ratio depends on the style of wheel (single
or doubledrive), some math is involved. For those interested
in determining the ratio more precisely, a nice explanation
is here.
So, what ratio should you choose? If you are aiming for
a thick and lofty yarn
with a soft hand, choose
something in the slower
range. A plied yarn will
use a medium or fast ratio
to spin finer singles.
Plying usually calls for
a whorl that is slightly
faster than the one used
to spin the singles. Obviously,
these are only general
guidelines! Your personal
drafting and treadling
rhythms as well as your
goals for the finished yarn will determine where you should
start sampling. The best way to get familiar with your wheel’s
range is to try all the
different ratios with a
variety of fibers and take
good notes so you can reproduce
the combinations that you
are happy with.
For inquiring minds with
the technical precision
of engineers, a very complete discussion of ratio can be
found in The
Alden Amos Big Book of Handspinning,
a dense tome, but one that,
if you work your way through, will give you the equivalent
of a master’s degree in Spinning
Theory.
