Hi Guys
I've got a CBR600f3 97.
It's been a year long build so far, but I'm nearing the end.
I'm curious about using alloy rear sprockets these days.
I know they will wear out faster than steel for sure.
BUT, what I don't know is, can I just put another one on when it wears out, but with the same chain?
I'm thinking the EK 520 GP chain will be far tougher than an alloy sprocket, so should fair well?
No it's not bling, yes it's for reducing gyroscopic weight.
I already have Ti bolts on the front and rear disc, and alloy (with steel insert) sprocket nuts from www.probolt.com
I will be getting a drilled front sprocket, the EK GP 520 chain (conversion I know), and either alloy or a Supersprox steel and alloy sprocket.

I know already what the general thoughts will be, but I'm wanting to know how many of you have done this, and did it turn to ****....or gold lol.

Before anyone says anything about wasting time on weight loss for an old bike.....
So far I have dropped 9kg (19.8Lb) off the bike, so yes, it will be enough to notice

Thanks

 

Yes I ran a few aluminum sprockets per the 20k or so I get from a chain. Got old, fast.

 

so it didn't affect your chain life at all then?
If not, that's good news to me

 

My last aluminum sprocket Looked great 30k+ later when I sold my f4i! I ran a vortex 60t

This is a pic of it right when it was around 20k miles. I even ran the cheapest chain I could find, "KMC" brand from ebay for $68 shipped.

All about keeping your chain clean, lubed, and properly adjusted!

 

They wear out faster and they're more expensive, but on the plus side they look nice and they help in the all-important unsprung weight category. Not really a right-or-wrong here, you'll just be buying them more often if you ride a lot.

 

thanks for the replies guys

 

Steel's good enough for us common folks

 

Well, it only saves 1 pound, and has a 5 inch radius, so has almost no gyroscopic effect. An H rated rear (130 mph all day long) will save 3 pounds and it's mostly at a radius of 10 to 12 inches, so it saves 12 to 17.3 times the gyroscopic effect. And you can feel it!

Also, when I weigh the 428 chain and 520 chain, they are the same. Not sure if the 520 weighs less than the 530. (I like the LiFePo batteries, they save 5 pounds. Shorai brand.)

I have run a 428 on my yzf600/fzr400 hybrid for 50,000 miles (plus 3000 when it was a 400), and use wd40 to keep it clean (every 200 miles). It's only halfway through the adjustment range, but half the teeth have broken off the rear sprocket. My yzf has pods and jet kit, and makes 90 hp (maybe 95) at the rear, compared to the stock 85 hp. Maybe I'll get a new AL rear and see if the chain can last another 50k. (Thanks for the idea.)

Once I bought a new steel front sprocket for my cbr after riding across country. The chain had maybe 3000 miles on it, and the new sprocket made it sound like a really loud reverse gear for a few hundred miles. Both ended up lasting just as long as any other chain of mine before I started using wd-40 (maybe 25,000 miles at the most).

That setup was using an aluminum rear that I put on when the chain had a few hundred miles on it from the previous owner (it came off the yzf). It made very little extra noise from then sprocket, and that noise was gone after a hundred miles or so.

I have always used aluminum rear sprockets, but I never will again since I started using wd-40 to keep my chain clean and make it last so long. BTW, I got the idea from a friend who did that with his Honda RS125 at the track (and made his tiny chain last twice as long) and another friend who always had the biggest Kawisaki (Z1, 900 Ninjas, 1200, 1400) and made his 530 chains last eons as well.

Curt

 

my thoughts are this, coming from a small displacement bike that punches above its weight class.

Lots of guys were running alloy rear sprockets.

Yes its less overall weight, but for me, its not about that as much.

To me its rotational mass. Like a flywheel. Helps the engine accelerate faster.

I don't like the idea that they wear down too fast, but it seems, from this thread that they last ok if you properly maintain your chain.

On to my question. What about those SuperSprox brand ones that are alloy but have a ring of steel teeth? Seems like the best of both worlds almost. My concern is that the mass of the steel is located at the outside, making the weighted leverage be placed at the worst place to minimize rotational mass. Also I am concerned that maybe the toothed ring might come loose over time being that its not just one piece of milled metal?

 

[QUOTE=John600rr; To me its rotational mass. Like a flywheel. Helps the engine accelerate faster.

On to my question. What about those SuperSprox brand ones that are alloy but have a ring of steel teeth? Seems like the best of both worlds almost. My concern is that the mass of the steel is located at the outside, making the weighted leverage be placed at the worst place to minimize rotational mass.]

Hey John,

Any of the three sprocket options make no noticeable difference in gyroscopic effect or acceleration on the brakes or gas. Here's the math without having to do the math. If you double the weight, you simply double the rotational kinetic energy. However, if you double the speed, you quadruple the energy. And most importantly, if you double the radius, you also quadruple the energy.

Since a steel sprocket weighs 2 pounds but an aluminum sprocket weighs 1 pound you might think it doubles the gyroscopic effect. However, the radius of the sprocket is more like 4.5 inches while the rim is 8.5 (half of 17 inches) and the tire is about 12.5 (half of 25 inches). And the rear tire weighs 14 pounds and the rim weighs maybe 5 pounds.

So, compare 1 pound at 4.5 inches vs 19 pounds averaging a radius of about 10.25 inches. The difference in energy is 19 times (10.25 / 4.5), which is 43.3! Considering the mass of the hub, spokes and brake rotor, that 1 extra pound in the sprocket is maybe 1/50th of the total energy, so about 2%. Can you feel it?

I can definitely feel when my 11 pound front tire looses 3 pounds of tread. But, that tire has cords showing. And it equates to more like 20% of gyroscopic effect.

For suspension action:

The entire rear wheel with rotor, bearings and spacer are about 15 pounds. The entire rear setup without sprocket is about 30 pounds. So, adding 1 pound or 2 pounds won't change that very much. One extra pound for steel is about 3%.

For acceleration:

The entire bike weighs 460 pounds if its an F1, F2 or F3. All this mass has to be accelerated to 60 mph (for instance). So, you see, there isn't much difference between 460 and 461. And the teeth on the sprocket are 4.5 inches from the center of rotation. These teeth are moving about 11 mph when the bike is doing 60. A few ounces here won't make a difference.

I recommend the Shorai lithium iron battery, because it saves 5 pounds.