Hi all, I bought a CNC sprocket from Amazon that JUST DOESN"T FIT my 415 chains! Should I try to work with it (shave down the teeth) or just get a new one?
My CNC rear sprocket DOESNT FIT. ARGGHHH
- Thread starter CrimsonPrince
- Start date
I had a similar situation with a sprocket whos teeth were darned-near square, viewed edge-on. Once I tapered them, it helped quite a bit.
How did you file them down? What kind of tool would you recommend? Honestly though, I'm thinking of just getting rid of my sprocket from Amazon and going with a T8F size sprocket with 54 teeth...
I’d advise you to return the 54t sprocket.
I miscalculated your gearing needs.
Since you’re running 20” wheels, then a 14.4:1 ratio is equivalent to 18.75:1 on a bike with 26” wheels.
A 40t sprocket with your 25t BMX, along with 54t/9t engine-jack shaft sprockets will yield 14.4:1.
Being a smaller sprocket than the 54t, the 40t should clear the frame stays easier.
I miscalculated your gearing needs.
Since you’re running 20” wheels, then a 14.4:1 ratio is equivalent to 18.75:1 on a bike with 26” wheels.
A 40t sprocket with your 25t BMX, along with 54t/9t engine-jack shaft sprockets will yield 14.4:1.
Being a smaller sprocket than the 54t, the 40t should clear the frame stays easier.
Thanks! May I ask what the basis of the calculation is?
I remember discussing the gearing ratios earlier, but I never thought it involved the wheel sizes!
Just out of curiosity, what happens if I have a very low gearing ratio like 24:1? How do you predict that it will affect the bike? What about a high gearing ratio like 4:1?
Just asking questions to get an idea, lol. Sorry for all the pestering inquiries! Thanks again for your time!
I know of my experience with first trying with 8:1 ratio and 26" wheel on a 3hp 4stroke Briggs. I weigh 135lb and the bike weight maybe 70lbs as lots of extra metal welded on for off roading on trails. This 8:1 ratio was not enough to even get the bike going well at all on flat ground.
I eventually have been using it at 20:1 and also 12:1 ratios. 20:1 better for steeper hills on trails, but 12:1 can work just not as good. Trade off top speed.
Not having made motor bikes with 2 stroke engines, I'm not sure if you can use this as a guide. I never saw mention of the type displacement and horsepower output. I did see that the size physically inside the frame on the 20 wheel bike leaves it to be where I would think 18:1 could be good.
Anyway why I am posting is since I found initially the difference between unusable at all with too high a ratio, and what works in my situation.
What does seem odd is the terminology higher ratio is a lower number with relation to the number 1. But that's OK.
I eventually have been using it at 20:1 and also 12:1 ratios. 20:1 better for steeper hills on trails, but 12:1 can work just not as good. Trade off top speed.
Not having made motor bikes with 2 stroke engines, I'm not sure if you can use this as a guide. I never saw mention of the type displacement and horsepower output. I did see that the size physically inside the frame on the 20 wheel bike leaves it to be where I would think 18:1 could be good.
Anyway why I am posting is since I found initially the difference between unusable at all with too high a ratio, and what works in my situation.
What does seem odd is the terminology higher ratio is a lower number with relation to the number 1. But that's OK.
A 24:1 ratio would have lots of low end power.
With 18.75:1, good all around power, even low end.
The 14.4:1 ratio should give you good power, along with using your pedals.
With 4:1 ratio, it’ll be like trying to pull away from a stop, in 4th gear with a truck.
Your clutch would self-destruct.
That’s a good reason to keep your pedals.
It wasn't the most scientific method- I took n angle-grinder and tapered the sides of the teeth, both sides. But in light of the fact that you need a different sprocket, don't touch it.
I had the same problem with a 44t cnc sprocket I bought. Teeth seemed squared and my chain kept trying to jump off it or the chain would bind and not want to turn freely.