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@DannyP and @dlearl476 (sorry, forget your first name?)- When I was drilling holes in my type 3 backing plates awhile back I weighed a type 1 piece bare (without the cylinder but it was a little dirty)- 1020 grams- 35.979 oz.  The type 3 backing plates I'm using weighed 1284 and 1285 g and was able to get them down to 850 and 849 g.  There's over 200 holes, as well as a lot of profiling of edges.  As you can see, I even reworked the block that holds the adjusters (as well as drilled out the middle- there's no reason for all that metal to be there!).  It really is a labor of love- I didn't come up with the complete pattern the first day- and to set up each time (on a small  drill press without a rotary table) so it's somewhat close to concentric takes forever. I don't want to think of the number of hours invested in just the backing plates and it's not even a pound reduction per side.

lightened type 3 rear backing plate

I believe that holes in the rotors improves stopping power as well (letting gases escape and improved rotor cooling and all) but it does have to be balanced with the minimum mass needed for the weight of the end of the car it is controlling.  There are several different hole patterns that have been proven to work- I believe the theory is to cover the whole rotor so no area gets hotter than another.  The holes need to be chamfered to help prevent cracking and the more air you can duct to them the more effective they will be.  Some believe that holes do nothing on the street and carved slots (just down to the minimum thickness of the rotor) are more effective.  What I think is really neat is the wave patterns now being used- this is a rear Corvette rotor- I'm really lovin' the way they carved up the hub as well!

lightened rear corvette rotor

One last thing to leave you with- an aftermarket rear rotor for a Suzuki bike by MM Racing- only 375 g (13.22 oz) - available with optional fully forged titanium bolts for further weight savings (only a paltry $69 option)!  I just noticed the maple leaf- I wonder it they're Canadian?  Just looked it up- Florida.  There's probably more I want to say here, but this is enough rambling for now...

Lightened Suzuki rear rotor MM Racing

Last edited by ALB

Well, once again, I worried needlessly. A simple matter of the casting being off center. All the important circles were concentric. Installed the bearings and put it on my MC tire balancer and it ran true. 

The balancer instructions say if it lands in the same place 3 times add weight to the opposite side. It consistently landed in the same place every time on both discs, so I dropped them off to get balanced. Should be good to abt 120.

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Last edited by dlearl476
@Carlos G posted:

@Lane Anderson Bicycle rotors do not come in 280mm. He's talking motorcycles.

BTW you can get a 15 lb road bike if you have the funds. A 25 lb road bike would not be considered all that good, weight wise. I might be a little jaded since I work in an adult toy store and deal with all those kinds of first world problems.

25 pounds is a really nice all-mountain with discs these days, isn't it?

Sub 20 pound road bikes are the norm these days.

@DannyP    A 25 lb mountain bike with discs is a very nice bike. You can get a sub 25 lb carbon hardtail with discs and a front fork.  25 lbs could be a race carbon full suspension. When you get more travel in the suspension, the weight starts going up. It's a toss up between wanting to go fast up hill or down hill.

@Gordon Nichols  Those E-bikes are porkers, but you can maintain 28 mph with a road version. The mountain version will assist up to 20 mph. It's good to have a buddy with an E-bike in the mix during windy days though. LOL Get your ass up front.

We've been selling the hell out of them. We've sold a few E-mountain bikes, but they're technically not legal on the trails around here. There is no enforcement, so who's going to know. They don't tear up the trails anymore than a regular bike. The Specialized bikes are so sleek, that if you don't know what your looking at, you'd never know it was an E-bike. I'm OK with them.

 

We actually have two road e-bikes in our small group and they are usually at the lower range of “boost” and just use it to keep up with the group.  I have seen a few older road bikers cruising along at 20+ mph on a road where I would be doing 18-ish and struggling.  
The biggest gripe I have with new e-bike owners is that they always want to go 50% farther than the rest of the group and are perfectly happy suggesting rides of 40 - 50 miles.  And the latest thing is they suggest routes that have 2,000+ feet of vertical climb over a couple of hours.  Sure, I can get there, but I’m not happy at the end of the ride.  The dynamics of road rides (and, I’m sure, trail rides) is quickly changing.

I see your point Gordon. Cycling is a competitive sport. I can see where someone might take advantage of his new found E-fitness. For those people, may their battery go dead during a hail storm.

We have a customer with a road E-bike. He has had some issues with his motor, where it would not work intermittently. This is being taken care of as a warranty. It happens. The point I wanted to bring up is what the customer said when his bike stopped assisting him. He said "my bike left me STRANDED again". I thought this was funny. His bike stopped assisting him so he had to do ALL the work himself. Whah. I wouldn't exactly call this stranding.

I feel E-bikes are a good thing, but it's going to get a lot of morons in over their heads.

Bikes. My specialty. Who here will admit to using a Ti Bolt kit? Lol. I’m no longer a weight weenie, but I do have a 15 lb bike. Had two mountain bikes up until recently. The 21 lb ‘lefty’ was stolen but the the 20 lb Ibis was not. Funny story. I was climbing up Torrey Pines Rd here in S. Cal and spotted a rabbit’. By the time I caught him, I was redlined. And that is when I realized the person was riding an e-bike

No pictures, Al.

I'll try this again-

@ALB posted:

@DannyP and @dlearl476 (sorry, forget your first name?)- When I was drilling holes in my type 3 backing plates awhile back I weighed a type 1 piece bare (without the cylinder but it was a little dirty)- 1020 grams- 35.979 oz.  The type 3 backing plates I'm using weighed 1284 and 1285 g and was able to get them down to 850 and 849 g.  There's over 200 holes, as well as a lot of profiling of edges.  As you can see, I even reworked the block that holds the adjusters (as well as drilled out the middle- there's no reason for all that metal to be there!).  It really is a labor of love- I didn't come up with the complete pattern the first day- and to set up each time (on a small  drill press without a rotary table) so it's somewhat close to concentric takes forever. I don't want to think of the number of hours invested in just the backing plates and it's not even a pound reduction per side.

lightened type 3 rear backing plate

I believe that holes in the rotors improves stopping power as well (letting gases escape and improved rotor cooling and all) but it does have to be balanced with the minimum mass needed for the weight of the end of the car it is controlling.  There are several different hole patterns that have been proven to work- I believe the theory is to cover the whole rotor so no area gets hotter than another.  The holes need to be chamfered to help prevent cracking and the more air you can duct to them the more effective they will be.  Some believe that holes do nothing on the street and carved slots (just down to the minimum thickness of the rotor) are more effective.  What I think is really neat is the wave patterns now being used- this is a rear Corvette rotor- I'm really lovin' the way they carved up the hub as well!

lightened rear corvette rotor

One last thing to leave you with- an aftermarket rear rotor for a Suzuki bike by MM Racing- only 375 g (13.22 oz) - available with optional fully forged titanium bolts for further weight savings (only a paltry $69 option)!  I just noticed the maple leaf- I wonder it they're Canadian?  Just looked it up- Florida.  There's probably more I want to say here, but this is enough rambling for now...

Lightened Suzuki rear rotor MM Racing

 

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  • lightened type 3 rear backing plate
  • lightened rear corvette rotor
  • Lightened Suzuki rear rotor MM Racing

(And now back to cars)

"I feel E-bikes are a good thing, but it's going to get a lot of morons in over their heads."

Sort of like all the driver assist technologies on cars these days.  I can't say anything as I would probably have hurt myself on the track without stability control.

Agreed. They'll go too fast and crash. Or, they'll go too far and run out of battery. Then, either complain at the bike shop, or end up having a heart attack pedaling back home!

My next-door neighbor has one. He has a VERY bad knee. He can barely walk, but the E-bike allows him to get out and enjoy some fresh air. That I completely understand.

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