Lighter Wheels/Lighter Wallet

[cencalal]

Tell me it ain't so, but my reading about lighter wheels for my 695 tells me I may have run out of cheap mods.  I've been having fun bolting on the upgrade stock chassis parts - 800 aluminum swingarm, 749 shock, 1000 adjustable Showa forks. But it looks like the only stock wheels that would be lighter than my 3-spoke wheels would be the 5-spoke Marchesini from the ST models?  Weight savings would be a bit more than two pounds on the front, and a bit less on the rear?  A set of these goes for more than $600 on ebay.  I'm wondering if this is worth doing.  Subjective, I know, and obviously the big weight savings to be had with aftermarket wheels would be way better, but I have a budget.  Is this more modest amount of weight loss much of an improvement?

[d3vi@nt]

I did a fair bit of research on this not too long ago. From what I read, those weights are correct; a bit over 2 pounds on the front and a bit over 1 pound on the rear.  I trolled e-bay for quite a while and buying the wheels separately came in at $500. But I'll easily blow a few more hundred in cush-drive bushings, bearings, and powder coating.

From what I've read, the difference is a noticeable but not huge. I'm sure the bulk depends on how perceptive a rider you are. I'm not convinced I'll notice a difference personally but wanted to see. Plus I think the 5-spokes look much better.

[Speeddog]

Yes, OEM 5-spoke fronts are ~2 lbs lighter than the OEM skinny 3-spoke.
I wager you'll definitely notice the difference, but it won't be dramatic.

Rear actually gains ~1 lb, as you'd be going from a 4.5" to a 5.5" width.
The 5-spoke is ~1 lb lighter than the 5.5" 3-spoke.

[cencalal]

I wouldn't want the rear wheel to gain weight, and while I like the look of the 5-spoke, I'd bet the 4.5 steers better.  But it seems there's no better 4.5 than the one I have...

[koko64]

So a net loss of 1 pound plus the weight of the bigger rear tyre?

[koko64]

If minimum weight is a goal, what about Ti engine to frame bolts from TPO and a Shorai battery? I know its not rotating mass but the battery mass is high and the Ti engine bolts stiffen the chassis and drop a pound or two at least. The battery may drop 8 pounds and make the bike feel like the tank is empty when its full. What exhausts are fitted? There also is the TPO Ti front axle, again lighter and stiffer than oem steel part. Also Michelin Pilot Pure tyres are very light so something to consider when tyres are due.

[Speeddog]

So a net loss of 1 pound plus the weight of the bigger rear tyre?

Yep, that's the windup for cencalal's 695.

d3vi@nt's ST2, though, will lose a whopping 3 pounds. 

I wouldn't want the rear wheel to gain weight, and while I like the look of the 5-spoke, I'd bet the 4.5 steers better.  But it seems there's no better 4.5 than the one I have...

I don't recall noticing a steering difference when I went from the 4.5" 3-spoke with a 160/60 to a 5.5" 5-spoke with a 180/55.
4 years ago, and it was worn out tire and driveline to new tire, wheel, and driveline, so ....

I'm not aware of any 5-spoke 4.5" OEM.

And yes, your 3-spoke is the lightest OEM 4.5 I've found.

[cencalal]

Overall weight loss isn't my main goal, and I'll be getting a Shorai battery when this one goes away.  But weight at the wheels is both rotational mass, and unsprung weight, so losing some there gives better acceleration, braking, steering, and suspension control - really the best money you could spend.  I don't know if I can spend $2K for aftermarket wheels, but I seem to be talking myself into it.   

[kopfjäger]

Best bang for the buck. Get the Marchesini wheels. You already know you want them, go for it.

[d3vi@nt]

But weight at the wheels is both rotational mass, and unsprung weight, so losing some there gives better acceleration, braking, steering, and suspension control - really the best money you could spend.  I don't know if I can spend $2K for aftermarket wheels, but I seem to be talking myself into it.   

Have you given any thought to lighter rotors? The weight's closer to the axle, but still rotating. You could drop at least a pound, maybe as much as three or four over stock and cost probably less than a used wheel-set. Ti rotor bolts might shave a bit more off rotating...

[Speeddog]

IIRC, he's still got the 300mm rotors mounted.

Those are only 3.5 lbs each, so uphill battle to save there.
BrakeTech 320mm are 3.5.
Brembo T-drive are 3.3.

If he went to a single 320 rotor with a single 4-pad caliper, he'd save about 5 pounds.
I ran my M750 that way for quite a while, and it worked fine for me on the street.
I'm riding occasionally 2-up now, and it didn't give me adequate confidence for that application.
If you ride really hard on the street, ride 2-up, or extreme mountain roads, I'd avoid that combo.

That's a great reduction in unsprung weight.

Given that a rotor is ~2/3 the diameter and ~1/3 the weight of a wheel, their moment of inertia is ~15% of that of the wheel.
IMO, unlikely that an incremental weight reduction of a rotor would be noticeable.
Removal of a rotor, that would be noticeable.

[koko64]

Tyres are at the very outer circumference of the wheel, so if expensive wheels are out of the budget then light tyres are worth a try when it's time to change them. Unfortunately reducing unsprung weight ain't cheap to do.
When I changed from the oem Sachs shock to a Penske I saved about 3 pounds. I have always also gone for drilled lightweight sprockets (not necessarily alloy). In the course of normal maintenance you can reduce a great deal of weight with careful choice of parts. Every little bit counts. I got my M900 down 15kgs from oem weight over time.

[cencalal]

Some good hints here that I hadn't thought about.  The aluminum swingarm saved nearly three pounds, but if I went to a 5.5 rear wheel, would I have chainline or other issues to deal with?  Some of the aftermarket wheels require a special sprocket...  Is there a 4.5 aftermarket rear wheel?

[Speeddog]

Some good hints here that I hadn't thought about.  The aluminum swingarm saved nearly three pounds, but if I went to a 5.5 rear wheel, would I have chainline or other issues to deal with?  Some of the aftermarket wheels require a special sprocket...  Is there a 4.5 aftermarket rear wheel?

5.5 wheel you'd need to get the matching chain rub strips that go on the swingarm.
And you'd need the 5.5 sprocket carrier so that the chain is out far enough to clear the tire.
And then you'd flip your front sprocket flat side out, and be all set.

Aftermarket wheels generally do not have OEM sprocket pattern, so, yeah, you'd need the appropriate sprocket.

Dunno about 4.5 aftermarket wheel.

[koko64]

Maybe One 320 disc and Berringer 6 pot caliper if you ride hard? Add a Ti axle and Shorai battery and you have reduced unsprung weight at the front and removed hi c of g weight from under the tank. Add some Pilot Pure tyres and some TPO engine to frame studs and the whole combination improves handling from a number of angles. Less unsprung weight, lower c of g, stiffer chassis, more front end feel and less rotating mass, all part of a recipe for better handling.