TREE BICYCLE - LITE SPROKET
WEIGHT
Weighed without spacer.
Size Grams Ounces
24t 74g 2.64oz
25t 80g 2.87oz
26t 105g 3.75oz
27t 107g 3.82oz
28t 112g 4.00oz
29t 117g 4.18oz
30t 124g 4.43oz
31t 131g 4.68oz
32t 153g 5.46oz
33t 153g 5.45oz
34t 161g 5.75oz
35t 178g 6.36oz
36t 185g 6.61oz
37t 193g 6.89oz
38t 229g 8.18oz
39t 232g 8.29oz
40t 240g 8.57oz
44t 298g 10.64oz
SPECS
-Made of 7075 t6 aluminum
-27t-44t sprockets are 5/16” thick
-24t-26t sprockets are 1/4” thick
-Sprocket is made with a 22mm center hole
-center hole sizes larger than 22mm can be made at special request, please contact us.
-comes with a steel adapter spacer for use on ¾”(19mm) spindles.
-1/8” wide teeth
-5 sprocket attachment bolt positions
-110mm bolt pattern on sprockets 33-44 tooth for us with any 110mm pattern sprocket guards.
REASON FOR MAKING IT
I wanted to make a sprocket that did not bend or break!! Something
you didn’t have to be gentle with when doing sprocket tricks. Something
that would outlast normal sprockets.
WHY IT WAS MADE THIS WAY
Strength-
The very first batch of sprockets we ever made was machined of
3/8” & 1/2” thick 6013 t6 aluminum. They were very thick but even
at that thickness they were bending and the teeth were breaking off. I
realized that 6013 was better than 6061, but it was very brittle and
the metal often cracked.
From then on I decided to use 7075 t6 aluminum which is 84%
stronger than 6061 t6 and 51% stronger than 6013 t6. The 6061 and 6013
grades don’t even compare.
We tested the 7075 sprockets by doing repeated air to sprocket bashes
on a coping to coping spine while using a motorcycle chain so we didn’t
have to keep replacing links. First I tried it with a Tree 7075
sprocket and then I tried it with the common 6061 sprocket. I would
slam the sprocket into the coping as hard as I could to try to bend it.
When I tested the 6061 sprocket the teeth were smashed in and
miss-shaped after 5 hits. With the Tree sprocket I slammed it as hard
as I could with the same force of hits in excess of 25 times. It did
not bend and the teeth had scratches on the side of them along with the
tooth valleys being pushed in just a little bit!!
Each gear size is specifically designed according to size. This
means the spokes on the 44t are wider than the spokes on the 25t, so
the 44t is just as strong as the 25t even though it is bigger.
Spindle Hole Size-
We are making all sprockets with a 22mm center hole from now on. I
designed the sprocket to fit directly onto a 22mm spindle with a high
tolerance fit. Each sprocket comes with a steel spacer for use on ¾”
spindles. The sprocket and spacer are machined to a high tolerance to
make sure the sprocket spins perfectly true and is well grounded to the
cranks.
The Spanish and Mid BB are becoming the new Bottom Bracket
standard for BMX. So this is why I decided to switch from the common
15/16” center hole that was originally designed for 1pcs cranks to the
22mm center hole. I made this decision with consideration of the future
progress of BMX bike part design by making sure our new standard does
not halt new ideas for cranks or spindle sizes. The next larger
possible size for spindles would be 25mm or 1 inch so that the spindles
would work with off the shelf bearings. And with both of these possible
spindle sizes it would still be necessary to buy a new sprocket or
machine out the current one whether the sprocket has a 22mm or 15/16”
center hole.
Teeth-
The sprocket accepts both 1/8 and 3/16 chains. Most sprockets are
machined with thin, short teeth but the Tree sprocket teeth are
machined to .13” wide for maximum tooth strength and .27” tall for a
smoother running drivetrain. And they are the right height so they can
not get hit during sprocket tricks. These teeth are very helpful when
riding a loose chain because the taller teeth keep the chain from
derailing.
These teeth have been modeled after the tooth shape used for
industrial machinery. In industrial situations this engineered tooth
shape keeps machinery running quietly and smoothly at very high RPM’s.
For BMX it makes the smoothest running sprocket ever made.
Design Process-
The sprocket was designed with the intent to make it the strongest
sprocket possible while keeping the same weight as a regular sprocket.
I chose to make it out of 5/16” thick 7075 aluminum. I drew the
sprocket so that the cutouts had mechanical reason for them to be
there. At the time this sprocket was designed most sprockets on the
market had holes machined into them without any thought about how it
would affect the strength of the sprocket. I drew and redrew the
sprocket many times until I decided that I came up with the best
sprocket idea that I could think of at that time.
It has 5 different crank arm bolt positions to help extent the life of the sprocket.
The sprocket is machined in a way that removes material from the
triangle shaped holes that is not needed and leaves the material
necessary to form a structure of high strength to weight.