Topic: Which weighs less? Front wheel hubs

[slikwilli420]

I weighed both bare hub types back to back and found they were nearly identical in weight.  I have a bare late hub on the shelf and I can grab an early hub from a wheel I was going to dismantle anyway.  I can weight them again if it matters.

George

If you are willing George that would be great. I would think that the later one was about 20% lighter at least given its design. I may just stick with a definned late hub for my new wheel if I don't get any information from GPS on their Barnes-style front hubs. I am really taking weight loss for me and the bike to heart. I know a CB750 can be competitive in this class, but it will take a fast and light bike with a light rider to get it done.

[754]

There are quite a few makers of those hubs, and used ones out there,
 They will almost always be 8 bolt.

[slikwilli420]

Talking with GPS right now about the set for front and rear. I have a rear that seems unfinished that I could make work but theirs come all ready to go. Probably send them right to Buchanan's to get measured for spokes and new hoops. Buy once, cry once. When these wheels are done, they will be the lightest and built with the best components available.

[bwaller]

After every attempt is made to carve off some grams, I'd be curious to know the savings. It's unsprung, and weight savings is important, but this is closest to the pivot point so less important than weight furthest away from that pivot...like a tube for example!

[754]

 Be careful, I bought a rear knockoff  wheel this summer, the guy was switching to Ducati mags, thought they were lighter ?
 Personally I think a lot if thought should be given to tire weights.
Generally the folks with hubs have spokes , sometimes cheaper than Buchanans..

[slikwilli420]

After every attempt is made to carve off some grams, I'd be curious to know the savings. It's unsprung, and weight savings is important, but this is closest to the pivot point so less important than weight furthest away from that pivot...like a tube for example!

I hear you on that but it's become a bit of an addiction this weight loss game. With the limits on brakes in the class any weight lost is worth the effort.

I would like to try the wheel sealing kits buy I hadn't not heard great things and a flat at 100mph doesn't sound like fun to save the weight of tubes.

[slikwilli420]

Be careful, I bought a rear knockoff  wheel this summer, the guy was switching to Ducati mags, thought they were lighter ?
 Personally I think a lot if thought should be given to tire weights.
Generally the folks with hubs have spokes , sometimes cheaper than Buchanans..

I don't follow. Which was lighter? The knock off or the mag?

What thoughts on tire weights?

[754]

 He said the mags were lighter, maybe they were Marchenesi? Pricey , I bet.
As far as trying to go  tubeless.. centrifugal force and tire pressure are constantly trying to insure the sealant onnthe nipples is working..

[bwaller]

I've had a tire (with tube) go flat quickly at race pace and it was damned funky until I realized what was happening. I've gone back and forth on tubeless kits but still use tubes. The safest option seems to be to use an MT style rim to help hold the tire bead from dropping into the rim center.

Frank, race tires certainly weigh less than any street tire I've ever used.

[gschuld]

The earlier hub with factory bearings, cross tube, and seals weighs 1530 grams
The later hub WITHOUT bearings, cross tube, and seals weighs 1217 grams.
I don't have another fresh front bearing kit on hand, but I weighed the pair of small wheel bearings from a new Allballz rear hub kit.  The pair of bearings weigh 285 grams.  They are a little bigger than front bearings, but the addition of the cross tube and seals likely come up to 285 grams.

1217+285 grams is 1502 grams, or 28 grams lighter than the comparable K hub.

The casting shape on the inside is very different between the two.  It's like a reverse of the late hub.

Anyway, that's what I got.

George

[slikwilli420]

I'm blown away at the lack of difference. The later really looks much lighter. I think an earlier one that has been definned and with some pockets cut between the rotor holes would beat the later in weight. Bummer. Now I will continue to pursue the billet flat track hub for new wheels. Add lightness is the name of the game.

[scottly]

I hear you on that but it's become a bit of an addiction this weight loss game. With the limits on brakes in the class any weight lost is worth the effort.

Welcome to the club; I've been a member for over 40 years. Just what are your limits on brakes?
The 8+mm holes in the hub are smaller than the recommended .328" for heli-coils, so that isn't an issue. Just switching from the stock long bolts and nuts to 1" long bolts with heli-coils would be a significant savings, perhaps 1/2 pound? I'll weigh some stuff tomorrow..   

[754]

Keep in mind Scottlys Seeley is around 410 in street trim..

[slikwilli420]

My bike is under 390 wet right now. Lots of meat left on the bone too.

For the class brakes need to be single 12"disc with 2 piston period caliper. Sharing a similar brake package with a bike weighing 90 pounds less is why weight is so important to me. My brakes are the very best they can be but only having one means something very different than having two.

[evinrude7]

slik, pardon me if this sounds noob.  after you get all your weight reducing work completed would you be willing to share a comprehensive list of what you changed?

[slikwilli420]

Yes of course! I don't mind sharing at all. I want people to learn what I have learned and since I am not making a buck on this stuff, there is nothing to hide. Part of it is me wanting to win a pissing contest against myself for the lightest CB750 in race trim. As far as I have gathered, my bike is getting awfully close to that point, but I still see a lot that is going to get attention. A lot of it is covered in my ARHMA race bike build thread in my signature.

[scottly]

The earlier hub with factory bearings, cross tube, and seals weighs 1530 grams
The later hub WITHOUT bearings, cross tube, and seals weighs 1217 grams.
I don't have another fresh front bearing kit on hand, but I weighed the pair of small wheel bearings from a new Allballz rear hub kit.  The pair of bearings weigh 285 grams.  They are a little bigger than front bearings, but the addition of the cross tube and seals likely come up to 285 grams.

1217+285 grams is 1502 grams, or 28 grams lighter than the comparable K hub.

The casting shape on the inside is very different between the two.  It's like a reverse of the late hub.

Anyway, that's what I got.

George

Your estimate was pretty close, George.
Wheel bearings 81 grams each
Retainer ring 10 grams
Inner spacer tube 116 grams
Outer brake-side seal (WTF is it doing, since there is a seal on the bearing?) 9 grams
Total 297 grams + 1217= 1514 grams

6 stock bolts with flange nuts 300 grams
An 8mm x30mm flange head bolt with a 10mm hex 16 grams x6= 96 grams
By replacing the inner spacer tube with an aluminum one of the same dimensions, there would be a weight savings of about 77 grams, and using the shorter bolts with heli-coils would shave another 204 grams, or almost 10 ounces. Trimming either the early or late hubs might result in another 4-6 ounces of weight loss without weakening the hub, but that's just a guess..

[754]

 I found a weight I recorded for the 350G 4 bolt hub.
In believe the 400 4 uses it too and they are 36 hole.
2 lbs 3 oz.

[slikwilli420]

Good info Frank.

I have decided to go all in on my wheels and am doing the GPS front hub and rear hub with adapters and knockoffs.

I think you posted the link earlier, but here it is again for all interested:

http://gps.racing/portfolios/hub-3/

How can I go wrong with billet front and rears? Lighter and stronger than stock. Really looking forward to the weight savings.

[seanbarney41]

Are you worried about a lack of cush drive for the rear?

[slikwilli420]

Not at all Sean. There is a cush drive in the primary to take up some of the shock. And it's a race bike so nothing is going to last forever. Plenty of guys running non cush hubs on road racers. I'm sure it's harder on transmissions but that is the cost of this mod.

[scottly]

For the class brakes need to be single 12"disc with 2 piston period caliper.

What period? Can you use a twin piston caliper from 1982? How much does your rotor weigh? The 297mm, 5mm thick Yamaha rotors I've been using weigh 2022 grams. Switching from a K7 caliper to a 30mm twin piston caliper increased the braking force from -.68G to -.75 G, the same as I dared to try with dual rotors and K7 calipers. Since I'm not restrained by rules, I'll be using a 320mm Ducati rotor, and will remove over 7 pounds of weight while increasing braking.
 

[slikwilli420]

2 piston opposed caliper like Grimeca or AP. Need to be of the period early 1970s. Cast iron rotor and carrier is just over 5 pounds. Running the appropriate sized master cylinder and racing pads there really isn't anything else to make the system better.

[754]

 Another one I found some weight notes on.. honda 200 that used a mechanical disc.
smaller narrower hub, but 6 bolt.  My weight note said 12 lbs on my untrusty hand scale.
And that was hub, bearings,  rim, spokes.................and skinny rib tire ! 
 I SUSPECT may be reaching the point of too light, 36 spoke I think.