ghezzi tech: the quest for lighter wheels

BST Carbon Fibre Wheels.
Currently I am developing a fitting kit so BST wheels can be fitted to my Bellagio.

Guzzi rear wheel/hub/mounting are all the same. (CARC models)

Guzzi front wheels have minor differences due to different forks/calipers etc.
However, they all run the same Brembo discs.(320mm 6 bolt x 80mm PCD and 64mm centre hole)

For my bike I have chosen to start with BST Black Diamond wheels for the Aprilia RS250, WHY?
1. Because I own an Aprilia 250 and I picked up a second hand set of unused BST's for it.
2. Same disc mount pattern and 25mm axle size.
3. This BST front wheel is 3.75" x 17", presumably for better edge grip.
3. It's narrower at the disc mounts so all I need are 2 x 6.7mm disc spacers to fit the Bellagio. Also 2 new axle spacers.
Other CARC models may require either a different BST front wheel or spacers, or both.
In any case, it is all very simple engineering as long as you are adding, not removing material.

For the rear wheel I will be using a conventional hub wheel, not an offset Ducati style wheel for single sided swingarm bikes. WHY?
1 (short version). Offset from bearing is too far. Already done by Rossopuro and Teo Lamers (see links by Steak)
2. I can unbolt the Aprilia disc/sprocket carriers and make my own drive/attachment system.
3. Ducati style offset wheels all mount from the r/h side, Guzzi is from the l/h side, so the wheel is turned around and slanted spokes are now leading, not trailing. BST offset wheel hubs, are not removable.
4. And I can still use these on my Aprilia RS250 (which by the way, happens to be a 485cc 2-Stroke)

The plan is to utilize as many off the shelf parts as possible, with the option of Ti billet & bolts etc.

But is your bst rear so flat on the side that you can mount it in the center and have some space for an adapter between wheel and carc? Becaue thats the problem with most chain driven wheels that they run to much outside the center. And thats why rossopuro and otehr italians made an adapter to mount a single arm ducati wheel, there are a few wheels that are symetrical for that. Post a picture of the bst center so I see how it looks.

Cast or forged, aluminium or magnesium conventional wheels are a problem as you would need to remove material from the hub area, upsetting the structural integrity of the wheel.

BST's have removable sprocket and disc carriers, their straight spoke conventional wheels are for Harleys and don't come in sport bike 17" sizes. (the 3" x 18" would be good for 850 Le Mans)

BST conventional wheels in 17" sizes are all 5 slanted spoke Black Diamond style, so here's a 3D link for you to spin and look at from all angles.
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Using half of a Ducati style axle (the top right portion of the pic) manufactured in 4340.
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The centre plate will be bolted directly to the back of the crownwheel and will include Guzzi rear disc mount. There will be no drive pins only a flange to centre the wheel as the BST rhs hub is only mounted via 5 x M6 screws with thread inserts in the carbon. There is approx. 30mm from crownwheel to carbon hub of the BST wheel, so just enough room for this mounting boss/spacer etc.

The drive system will be via the shaft (keyed into the hollow back of the crownwheel) and passing thru the centre of the wheel. The mounting points on the left hand side of the BST use 5 x M8 bolts with sleeves that pass thru the carbon and nuts and washers inside the carbon hub. This is where the cush drive would mount for a chain drive bike. Guzzi CARC models have cush drive in the transmission.
What I will say at this stage, the BST wheels haven't arrived so the above is just a theory at this point. Yet it is just one version of three different mounting options I have.

I had contact in the past with BST about wheels for the daytona, and then they could make me a set, but for the rear they had a special mounting for the hubs so they could do it, and not the customer. Maybe they changed that in the end.

Mine is a CARC? Daytona is double sided swingarm.

Currently they have nothing on offer for any Guzzi's. They will not sell me carbon blanks, only complete wheels. Let's say they are not "openly encouraging me" to modify their product.

I am buying 2nd hand BST wheels, which are for another bike I own. When I have the wheels in hand the exploration process begins. I have received wildly conflicting information from those who were free to offer it, and nothing by those from whom I wanted it. Education is never cheap.

Anybody on this forum with serious engineering background please chip in here, or PM me, or ring 0400816885.

Wheels in hand, alloy hubs successfully separated from rear carbon wheel - stage 1 complete.
Stage 2 begins, reconstruction Guzzi style .....................


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DAMN!!!!!
Scary Sweet.

It looks hollow between the two sides, what was the center that you removed like?
No bushes in carbon for the bolts? just holes where bolts go through from one side to the other?
Doesn't look to difficult to make a new fitting center for it.

Start with drawing the right part of your rear wheel, then you have the fitting to the carc and brake adapter. On that you make the fitting part for the wheel. It looks like the original 4 bolts with go through the center, that would make life easy.

Gentlemen, this is a journey of self education and discovery and could get ugly, but I've already given up beer and sex. The following is a reply from BST;

We never sell wheels without hubs, I’m really sorry, and we can’t help you with what you are doing – it invokes all sorts of safety issues and we would be very concerned about you riding on wheels that have been so heavily modified. Replacing the hub by whatever means and with whatever you are planning will undoubtedly cause the wheel to not run true.  Our wheels go through a machining process on their own hubs to ensure that the run-out is minimal.  And the biggest concern is how your would attach whatever hubs you are planning.  Please understand our safety concerns and just be aware that all our warranties are invalidated by tampering with the hubs.

I too can fit hubs bonded with aerospace adhesives and bolted, then machine the centre holes etc.

This is another email from the same person at BST - sent 10 weeks later on 1st of October - after the job was completed;
Wayne this is amazing!  What a job you undertook – and thanks for sending the pic!  If we put the pic on the web we’ll get enquiries which I will then direct to YOU!
Nice to hear from you and to get an update, thanks again J

terry

were the hubs glued on the carbon?

Yes!
Paul, it took two of us nearly a whole day to remove the BST hubs. I had previous access to drawings so we knew the order of removal, but had to make tools and develop techniques along the way.

I considered posting a detailed description of the construction process and our destruction dismantling procedure, but there are too many Wally's in Cyberland with a big hammer, and somebody will get hurt, Bloody Nora, I sound like Terry from BST.

If there are people on this forum who definitely want to duplicate the process, I will help them off-line.

I shall continue to post development here, my machinist will arrive shortly and the fun begins.

So what Terry seems to tell, is that they first glue/mount the hubs and do some machining afterwards.
What to take as reference point to get them true, just the rim sides?

Yes. It would only be the bearing lands/mounts. But then what happens to the disc and sprocket carriers? Would they run out of round? I would think their initial machining and moulding would be scarcely more than a few thou off true centre.

Peter my machinist is not phased by any design difficulties. Whenever he is presented with a complex problem he will pause for a moment, then say, "I can make a tool for that".
We can do exactly the same, mount then centre bore.

Update/edit 1st October - But we didn't.

ghezzi wrote:

Yes. It would only be the bearing lands/mounts. But then what happens to the disc and sprocket carriers? Would they run out of round? I would think their initial machining and moulding would be scarcely more than a few thou off true centre.

Peter my machinist is not phased by any design difficulties. Whenever he is presented with a complex problem he will pause for a moment, then say, "I can make a tool for that".
We can do exactly the same, mount then centre bore.

Because single sided swingarm, it is easy, not even a bearing to mount. Only the disk and center mounting to take care off.

Could also be that they glued it while pressing against a in line fixed part. Can you measure differences in the hub, because when they machined afterwards you should be able to measure them as uneven thickness.

Trust me Paul, I've been on this band wagon a long time and have several options, now with wheels in hand we can begin the development.

First the front wheel.

Front wheel - OEM left hand side axle spacer appears close fit for the BST alignment.
New right side spacer will be made tomorrow.

And ordered these
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gorgeousness.

I just got new front pads
FA244HH sintered.
I have heard that they may warp the front rotors.
will be installing the pads today and then finding out what happens to my rotors.
IF the rotors suffer I will be looking for "upgrades".

DM

Bella, seems to have a habit of warping discs (2 sets). Buttons cleaned and spun, surface scrubbed and block sanded. Metal Gear are $400 a pair but both sets are not full floaters. Also noticed replacements direct from Brembo are 5mm thick as opposed to 4mm. Above Braketech's are US$720 a pair.

In fitting the BST we discovered 3 things:
1. The unmolested stock BST front wheel has a side to side deflexion of 1mm, but this could just be variations in resin/lacquer thickness of 0.020" in each side. Will measure again on the inside at the bead.
2. Loosening/tightening the fork brace changes the distance between the forks at the axle point a smidge.
3. The axle faintly binds at the same point on every revolution. Might be bent a smidge also.

Might be time to check forks and triples as well.

DM, my bike was fitted with HH pads from Brembo since new - I went to change them out at the 55,000 km service but the originals were like new - just cleaned the dust from the grooves. I too have the FA244HH pads but still yet to use them. I did replace the rears though - they were a little warn but not much.

I had "warped" rotors but judicious freeing of the bobbins has fixed the warping and they now pull up true. Luckily I received a new disk from MG under warranty, though in hindsight was not needed, but cam in handy when I dropped my bike getting it off a trailer and bent the disk carrier. Lucky I had a spare.

Wayne, nice disks!

I heard about the HH's when I got my bike a year ago and I said to myself "I will do it when the original pads wear out."
Which is what I did.

What a bunch of crap!!!!
Don't wait.
Do it now!!!!!!

DM

Front wheel is done, just need to fit my Michy PP3 and new rotors. Bonny SE front guard is on the shopping list. Using the RS250 wheel we needed disc spacers 6.7mm thick and 2 different axle spacers.


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For the past 2 years I have run with my forks raised thru the clamps by 13mm. The difference in tyre radius between my old 18" Pilot Road 3, and my new 17" Pilot Power 3 is exactly 13mm. So I have moved the forks back down to their original position. A lap of the car park on the 125/80 slick and the steering is lighter/quicker.

For the GRiSO a Ducati SC1000 or Monster wheel would be a lot closer to direct fit.

Bike Porn!!

Put my Michelin Pilot Power 3 and OEM mudguard on today. Total front wheel weight saving, 4.0kg. (stock wheel with tyre, stock discs, bearings & spacers was 14.6kg, BST is 10.6kg)
BrakeTech axis iron discs will save another 500g.
In a straight line the bike feels eerily light in the front end, and very very smooth. Haven't changed any suspension settings yet, have a set of raised manhole covers up the road and the front just absorbs it all completely. By comparison the rear seems to be lazy in response, and gets air borne, possibly the difference is unsprung weight.

Doing the zig-zag it is very responsive and changes direction much faster, with whole lot less effort.
Thru a 60kph 'S' bend it was light, precise and turned in with ease and speed.

Now to see how much we lose (or gain) with the rear end conversion, and down sizing to a 160/60.


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click on above video link

Interestingly the rear carbon (only) with valve stem and stainless thread inserts/crush tubes weighs 2315 grams
The complete alloy hubs, bearings, bolts, spacers, crush tubes and cush drive w/o a sprocket, weighs another 2555 grams.
The BST 5.0" x 17" wheel would weigh 4.87kg,  plus weight of tyre and sprocket.

Got in a 220k ride today. Steering is light, response to any desired change of direction is quick and;
"the agility in the flip flop is increased considerably"
Loving it.

Bum dyno would even say engine braking has increased, as the weight of the inline front flywheel has decreased.

BrakeTech Axis Iron rotors arrived today, pleasantly surprised as they are lighter than stock.

Stock Brembo: 4mm thick, semi floater, warped and weigh 1684g each
Metal Gear disc: 4mm thick, semi floater, warped and weigh 1682g each.
Brake Tech disc: 5mm thick, full floater and weigh 1428g each. Front wheel weight saving now stands at 4.5kg

Grimeca disc: 4.5mm thick, semi floater and weigh 1244g each. According to daytonapaul only 122Euro direct from Piaggio (see next page) for an RSV4.

Haven't got to the full wank of Ti bolts yet, if I do it will be more for the shiny look as my original bolts are dull and corroded.

Stock M8 x 20 bolts are 11g each (x 12 = 132g)
Stainless button head are 9g each (x 12 = 108g)
Titanium flanged hex head are 6g each (x 12 = 72g)
$120 to save 60g = $2/gr for weight saving, yep, that's a wank factor of   
At least the front wheel has only cost me 37.5 cents per gram of weight saving, so far.