Mirage TS chain question

sfcpiet said:
Not really.

Less weight + less inertia = more avaiable (less wasted) power, and it's more or less for free!

piet
Click to expand...

I understand the theory, but my point was:  are the difficult savings going from 530 to 520 worthwhile, compared to the easy savings going from 630 to 530....

As far as I see it, it's the old 80:20 rule. 80% of the benefit for 20% of the effort. Wouldn't want to expend the other 80% for limited benefit.

It's not free for us mere mortals, as we have neither the skills or equipment to machine stuff.

My gut feeling tells me that the saving from going 530 - 520 is a fraction of 630 - 530  (dunno)

Pete
 
If you're replacing the chain/sprockets anyway, I don't imagine there's much of a price difference between the different sized chains. The only headache is finding 520 sprockets or modifying 530's. But machining down 530s is a simple enough operation so an engineering shop could do it for not a lot of money.

The advantage of reducing the size of the chain is that it reduces the rotating mass and associated stress as the chain whizzes around the small gearbox sprocket. One of the spin-offs is less liklihood of chain breakages and the resulting carnage to the crankcase (the chain side plates and pins are the same so a 520 is just as strong as a 530). My Jota has already had one chain take a bite out of the upper crankcase casting. I'm keen to avoid a recurrence.

Several sources say that a lighter chain improves the efficiency of power transmission, but I remain sceptical on that point. I can't see where any energy saving would come from in a properly adjusted chain drive The drive afficiency is related to frictional losses, not chain mass (a poorly tensioned chain has different dynamics and will have a mass component to the energy loss).

If anyone is thinking of mentioning reciprocating mass, forget it. Firstly, chains don't reciprocate. Secondly, reciprocating masses don't absorb energy. If you can't get your head around that, go read up on chain trajectory analysis. Here's a nice simple paper to get your teeth into http://www.simpack.com/fileadmin/simpack/doc/mbd05_hippmann_arnold_schittenhelm.pdf
:D

Cam
 
If that's a nice simple paper Cam, I'd hate to see an in-depth one :D
 
Dellortoman said:
If anyone is thinking of mentioning reciprocating mass, forget it. Firstly, chains don't reciprocate. Secondly, reciprocating masses don't absorb energy.
Click to expand...

Cam, my drive chain moves along the lower chain run, wraps around the rear sprocket, moves along the upper chain run, wraps around the front sprocket, and begins the cycle again. Granted it isn't a single isolated mass undergoing these transformations, but each discrete unit of the chain is undergoing reciprocal motion.
And, to reverse the direction of motion of this hypothetical discrete unit, the sprockets have to do a quite considerable amount of work to reverse the direction of the momentum vector. So, yeah, a motorcycle chain isn't reciprocating; it just requires a constant input of energy to revers itself (twice).
And I couldn't understand the article you cited either, I'm a chemist.

Ken
 
G'day Ken

That's a flawed analysis. You've fallen into a trap that is often the stimulus for perpetual motion theorists.  :D

A chain link follows a circular path while going around the sprocket, and a linear path between sprockets. Neither circular nor linear motion absorb energy. The linear bit is easy to understand - it's Newton's First Law. The circular bit is not so straight-forward, but have a rummage around in your memory for the circular motion physics you learned in high school. You may recall that to move a a chain link in a circular path around a sprocket requires a force on the link radial to the sprocket. A radial force doesn't alter the torque input or output at the sprocket, so can't absorb energy.  If the force had a component in the direction of the chain motion, then yes, there would be an energy input required simply to turn it. But all mass-related forces are perpendicular to the chain. In addition, the rotational or mass-related forces at one sprocket are balanced by those same (opposite) forces at the other, regardless of relative sprocket diameters.

But what about the transition form linear to circular motion. Well, nothing happens there either. It simply ceases to be linear and commences to be circular. There is no transition phase (ie, the time duration to change from one to the other is zero, so any power lost is also zero).

If you're not convinced, have a think about energy. How does a chain link travelling within a closed path (whether circular, elliptical, or any other shape) absorb energy? The answer is that it doesn't. There's a thermodynamic principle here, related to the First Law: "If a particle travels in a closed loop, the net work done (the sum of the force acting along the path multiplied by the distance travelled) is zero". The only energy input required is simply that necessary to overcome friction.

It's similar to an orbiting satellite, which is changing direction all the time, but it doesn't absorb energy. If it did, the orbit would decay very rapidly. Reciprocal motion is just a particular case of orbital motion where the minor axis of the orbital ellipse is zero. A mass orbiting in such a way will travel back and forth, changing direction by 180 deg at each end, and it still doesn't absorb energy.

Cam
 
Come on guys this has been done to death before.

For racers there are some reasons to use 520, however most use non O ring.

Here is the rub, most 520 are Jap and have big side plates meaning more weight
the iwis, yes I do like the stuff, has thin plates and weighs in at 0.95 kg per mt.
compare that with Jap 520. The guys in OZ did some comparrisons eons ago and
confirmed this. The only real savings is the sprockets and if your using alloy ones
then not really huge gains.

On road bikes it really does make no sense to change at all, yes there will be savings
in weight going from 530 O ring to 520 O ring but also a reduction in bearing surface
meaning shorter life.

Having just changed the gearing on the trusty Bandit 1200 I will be replacing the
3 year old iwis 530 chain (running a standard spring clip) not because it is worn but
because it is looking a bit rusty.

Dont get me started on the quote "it must be good, the racers use it". I had a guy
ring yesterday wanting a chain "to get round a few laps of the TT". I told him to buy
a ?20 RK instead of the ?150 "race" chain he was currently using. In his words the
current chain was getting tight spots. I put him right by telling him how to untighten
his tight spots and now wait for him to order a ?30 Regina gold.

For my OZ mates uuurrrruu.

Andy 
 
Hear Hear Andy,Perhaps castration/removal of dentures and drilling holes in the tool tray would save the weight loss as another option? :D :D
 
I understand the theory, but my point was:  are the difficult savings going from 530 to 520 worthwhile, compared to the easy savings going from 630 to 530....

As far as I see it, it's the old 80:20 rule. 80% of the benefit for 20% of the effort. Wouldn't want to expend the other 80% for limited benefit.

It's not free for us mere mortals, as we have neither the skills or equipment to machine stuff.

My gut feeling tells me that the saving from going 530 - 520 is a fraction of 630 - 530  dunno

Pete
Click to expand...

Take your point Pete - but this forum would be a bit boring if we all stuck to normal servicing and rebuilding. I do have machinery and facilities more than most - but less than others. I really enjoy trying to do all the modifications I can myself and spending as little cash as possible. In my case the "520" modification is to gain an extra 6mm of offset to allow me to use a different rear hub that I bought ever so cheaply. I was also very lucky that the manufacturer (Duplex Tools) of my toolpost grinder was situated virtually over the road from where I used to live and I did a very cheap deal on it just before the owner retired. - Regards - Phil
 
Phil,

Good point Phil. Making life more interesting and gaining a bit of space I do understand  ;). 

Pete
 
Got no probs Phil, if youve got special bits then sometimes there is no option but
to chop stuff about.

I refer to those with standard machines.

The number of guys I know that have changed from 530 to 520 on old British bikes
like Triumph, BSA and even Vincents and then regretted it astounds me. A lot go that route
so they can install an O ring chain and then wonder why their 30hp machine becomes a bit
sluggish.

Long live change and invention but only where it is needed or gives some profit.

Andy
 
mar said:
Damn, all this talk over a simple issue has me too confused. :o

I think I'll take the Moto Guzzi out for a while. :D
Click to expand...

Mar have you tried the aluminium cased shaft option on the Guzzi :D
 
i renew this topic.

I decided to replace my front and rear sprocket and chain . Now i have a heavy 630, I want to change to 530.
Did anybody this purchase lately. Where is best price? I need two kits(4 sprocket two chains) because I have two Mirage 1200 TS. year 1982 that need change.
I'm from Europe, so i prefer to order in Europe , because of weight and shipping costs.

Thanks in advance
Martin
 
If there is a problem sourcing it is simple to re-tooth the current
sprockets, again if the rear is flat ask for a 10B-1 platewheel with
the number of teeth you need and get it machined.

The price of the blanks is low but due to the weight the postage
is often more than the parts.

A front sprocket can be re-toothed for around ?40, Nametab Eng
are good. Or you could go for making a new one.

Andy

PS I am sure that these conversions are available I know Chas at B&C Express
used to have them
 
andychain said:
Dont get me started on the quote "it must be good, the racers use it". I had a guy
ring yesterday wanting a chain "to get round a few laps of the TT". I told him to buy
a ?20 RK instead of the ?150 "race" chain he was currently using. In his words the
current chain was getting tight spots. I put him right by telling him how to untighten
his tight spots and now wait for him to order a ?30 Regina gold.
For my OZ mates uuurrrruu.

Andy
Click to expand...

Ha Andy,how about enlightening us all,any chance of a chain lecture at The Barry Sheene,in Sydney in a couple of weeks.The weathers nice this time of the year
 
Hello!

Another question. While I'm looking for sprockets, I see that out there are available many 530 sprockets with different numbers of teeth. Cos my bike is not home now, I cant count how many teeth has Mirage 1200 sprokets now. Here https://www.laverda-paradies.de/shop-1000-58-en.html  i see that rear sprocket can be from 37 to 42 teeth...

What you suggest me for normal ride, sometimes with a co passenger?

Thanks
 
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