Anyone ever try a 7 tooth front sprocket?
Posted April 22, 2002 - 07:39 AM
Went to unload my bike for the Hare Scrambles, and my friend pointed out I was "a tooth or two". Turned out I was missing EVERY OTHER TOOTH! Problem was, I could only find a 13 tooth at the porta-store. Got the holeshot, but than people passed me on the straightaway like I was tied down! Could keep the whoops timed either. Bike wouldn't stall though...
Does anybody know how much top end you lose by dropping one tooth up front??
Posted April 22, 2002 - 09:01 PM
Posted April 22, 2002 - 09:19 PM
13/14 x 88mph = 81.7 mph
This only applies if if the top speed of a stock 426 actually is 88 mph, and you're hitting the rev limiter with either sprocket.
[ April 22, 2002: Message edited by: holeshot ]
Posted April 22, 2002 - 09:22 PM
I am not being an a hole but......
If you drop a tooth on the front it is actually like adding a couple to the back.(depending on your front-back ratio currently, it is usually somewhere between 2 and 3)
Just think of it this way if you disaggree.
If the front sprocket is smaller it will need to turn more times to cover the same distance it is current doing........Right?
On the back it is the opposite.....
If you have a 51 tooth and drop it to 45t , your wheel would turn quite a bit more if you pulled the chain around 1 complete revelution right?
Get out your mountain bike and look to see which sprockets you are using to go as SLOW as you can and as FAST as you can if you don't believe me.
Whenever I motox or woods ride I always drop to a 13t front and 15 when it is a high speed open DEZ race.
Posted April 22, 2002 - 09:24 PM
I am the Ahole here Oppps I mean EgoAhole
You are correct, Raising Counter 1 = 2 to the back
and Visa Versa.......
Posted April 22, 2002 - 11:00 AM
Posted April 22, 2002 - 11:19 AM
Pi are round not square and last time I looked its 3.14 still+- a couple of decimal points. So actually dropping 1 in front is like 3.14 in the rear. Do your math. 13/49 combo yeilds a 3.769 final drive. 14/49 yields a 3.5 final drive. NOW less seee what we get with say 14/52...3.71 pretty dang close aint it?
IM such the gear head.
Posted April 22, 2002 - 11:47 AM
Shawns Got a Braaaaaain
Ya know thats true Pie Vs pi, I myslef love Boston Creme Pi, next to me moms lemon Lime of course.
But I really never met a Pi I did not like
[ April 22, 2002: Message edited by: EgoAhole ]
Posted April 22, 2002 - 01:28 PM
Posted April 22, 2002 - 08:29 PM
Posted April 23, 2002 - 04:43 AM
Posted April 23, 2002 - 05:17 AM
You could use pi and the ratio of the circumferences, but it would be a pain in the ass.
Posted April 23, 2002 - 07:54 AM
14/48 (mine) = .2917
.2917 is the amount of rotations the rear wheel will do for every rotation of the counter shaft. if you know the internal gear reductions from your crank, you can figure out unloaded, uninhibited (no wind resistance or friction) top speed. just compare that with a different sprocket size, and you can figure out how much of a drop or increase in top speed you will have.
hmmm....that almost sounds like it would work!
Posted April 23, 2002 - 04:06 PM
Posted April 23, 2002 - 07:09 PM
plus, 15 x 15 for practice at rausch = 225
plus 30 x 3 for another place = 90
plus 2 sets of tires a year @ 115/pair = 330
plus oil @ 5.50/quart x 1.25 quart per change x 14 changes = 96.25
plus repairs or dumb things totaling around 800
$1891.25 a year in riding. assuming thats IT.
I could be so much more well off without that bike.
Posted April 24, 2002 - 08:27 AM
If you then multiply this number times the circumference of the rear wheel (with tire) you will get the linear speed of the bike.
The circumference of the rear wheel, and the maximum revolutions per second of the countershaft sprocket don't change.
Therefore, we can set up a direct variation; Speed varies directly with the gear ratio, or speed = k(ratio) where k represents the constants; max rps and wheel cir......
Since 88 is the supposed top speed with 14/49 gearing, k = 308 and you can figure out your theoretical top speed with different gearing.
I have 14/51 gearing, so my top speed should be (14/51)*308 which is 84.5 mph. So I lose about 3.5 mph for 2 teeth.
Just something to think about.
P.S. I was trying to stay awake this morning at 3:14 while feeding my 6 week old son, and this is the crap that I ended up thinking about. :-) I think when I saw the time, it got me on the subject.
Posted April 24, 2002 - 08:50 AM
49/51 X 88 mph = 84.5 mph
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