11 inch (283mm) brake rotor.

[recumpence]

Hey Guys,

Here is one of my latest projects. FFR trikes and I have collaborated on this. It is my idea, design, and funds, with their CAD work.

This is the first we made (I have two on hand to mount to my yellow trike). This rotor is being developed in an attempt to increase braking power, while decreasing rotor heat and pad wear from overuse. I blue the rotors on all my bikes. This should cure that while adding more braking power to our heavier than stock bikes.

This rotor is a prototype. I hope to offer these for sale within a month or so. The rotor itself will sell for somewhere around $45. The caliper mount will be another $40 to $45 depending on the design and machining time.

I have not tested this rotor yet. It was lazer cut from stainless (I think it was 303?). The lazer shop provided the material and said it was the hardest they had in stock. So, we will see how well it wears. Obviously, material type is important on a brake rotor. So, I need to get this one tested and try other materials as well to find the best option.

Anyway, I will let you guys know when they are available.

Oh, the one picture is of the rotor on a KMX 16 inch front wheel. I wanted to make sure the rotor was large enough to give the maximum braking power, while being small enough to use on the front of KMX trikes. :wink:

Lastly, this rotor weighs 356 grams.

Matt

 

[liveforphysics]

Tell them, straight spokes! They can come off the hub at an angle, but if the spokes have a curve, its asking for the rotor to fold.

 

[Ypedal]

Mine are bigger !

 

[recumpence]

Tell them, straight spokes! They can come off the hub at an angle, but if the spokes have a curve, its asking for the rotor to fold.

I wondered about that. I figured curved would be better to allow heat growth without warping. But, I see your point.

Well, I will test it and see!

Matt

 

[liveforphysics]

The spokes need tension more than compressive strength. Curve them and its like a wheel with loose spokes you lost all the strength.

Rotor design is pretty complex stuff. Most people/companies make things that look neat but suck.

 

[fizzit]

What forks/spokes can actually handle that much braking torque? :|

 

[recumpence]

The spokes need tension more than compressive strength. Curve them and its like a wheel with loose spokes you lost all the strength.

Rotor design is pretty complex stuff. Most people/companies make things that look neat but suck.

Hmm, the problem I see with that is the fact that under tension, the outer ring of the disc will want to collaps inward and fold. Every single rotor I have ever seen runs the spoke in compression, not tension.

Matt

 

[liveforphysics]

The spokes need tension more than compressive strength. Curve them and its like a wheel with loose spokes you lost all the strength.

Rotor design is pretty complex stuff. Most people/companies make things that look neat but suck.

Hmm, the problem I see with that is the fact that under tension, the outer ring of the disc will want to collaps inward and fold. Every single rotor I have ever seen runs the spoke in compression, not tension.

Matt

No.

A ring is ideal tension loading shape actually... in fact, it's the ideal stress riser absent load distribution optimization (not better shape for tension) This is how a bicycle wheel works, the reason a dome is so strong, the reason a submarine is round etc.

Performance motorcycle's/cars all float the disk for thermal expansion reasons, so it load the tips of the hat in shear load, and has no tension or compression.

Bicycle disks don't float, they sacrifice this to gain the strength of having spoked strength, this lets them be very thin and light compared to other brake rotors. What they sacrific for this strength of the spoked design is what makes them warp like a beech everytime you stop fast (as you an I know better than anyone on this forum from each warping and wadding up a stack of brake disks.)

 

[flathill]

Tension and compression are inseparable. A tensioned rope is compressively contracted. A compressed column will expand like a cigar (horizontal girth in tension). It takes a minimum of 12 spokes to lock a hub in a rim. Luke is right you don't want curved spokes.

 

[liveforphysics]

Logical rotor designs to copy:

Designs to copy if you really want curved members in the hat (just to weaken it I guess), and wish to eliminate warping rotors, as the rotor floats so the temp difference between the hat and braking surface doesn't matter. For floaters, you can curve them any way you like if you insist on being heavier and slightly weaker for styling reasons or whatever.

Some of the floaters blew it though and made large protrusions down from the hot part of the disk, so they are STILL going to warp even though they went through 90% of the effort to fix the problem, but didn't want to spend the extra $2 of aluminum material to make the hat go clear to the edge...

 

[recumpence]

Logical rotor designs to copy:

Designs to copy if you really want curved members in the hat (just to weaken it I guess), and wish to eliminate warping rotors, as the rotor floats so the temp difference between the hat and braking surface doesn't matter. For floaters, you can curve them any way you like if you insist on being heavier and slightly weaker for styling reasons or whatever.

Some of the floaters blew it though and made large protrusions down from the hot part of the disk, so they are STILL going to warp even though they went through 90% of the effort to fix the problem, but didn't want to spend the extra $2 of aluminum material to make the hat go clear to the edge...

Hey Buddy,

I think we are talking past each other. My rotors are setup exactly like the pictures you posted. If you look, the rotor pictures you posted show the direction of rotation puts the spoke under compression and the ring at tension.

Matt

 

[liveforphysics]

Nothing that spoke can do in compression (espically a curved one)gets it a happy meal.


Does this make sense?
To be strong in compression you must have something to prevent flexing/bowing when loaded.

To be strong on tension, you just need to be attached on each end and the system forces itself straight.


I think what you're trying to say now is that you want to mount it backwards??? So the offset from the hub helps to try to jam the spokes against the disk so they flex and bow and warp and fold up rather than mount it in the direction that lets the offset all pull evenly against the disk forcing it to stay straight and center in 2 planes???

 

[deVries]

Bicycle disks don't float, they sacrifice this to gain the strength of having spoked strength, this lets them be very thin and light compared to other brake rotors. What they sacrific for this strength of the spoked design is what makes them warp like a beech everytime you stop fast (as you an I know better than anyone on this forum from each warping and wadding up a stack of brake disks.)

What's the best eBike brake design/size (brand) that will reduce replacing brake pads? I want brakes that last a L O N G time before having to replace pads, so I'm looking for the longest brake pad wear possible -within reason.

Can someone suggest how to solve this issue?

What about Drum brakes too vs Disc?

 

[Thud]

deVries,
if you want ridiculas power that is perfectly controlable at a price no bicycle components can touch. try these:
http://www.partsforscooters.com/Hydraulic_brake_front?sc=2&category=77226

I ran one on my death race bike & now have one on my 26" mountain bike also. so far the pad wear is looking great. sinple to adapt to a bike also...if your going to go moped speeds use moped brakes i say. :wink:

 

[nicobie]

Thanks Thud. I was wondering where you got yours.

 

[liveforphysics]

deVries,
if you want ridiculas power that is perfectly controlable at a price no bicycle components can touch. try these:
http://www.partsforscooters.com/Hydraulic_brake_front?sc=2&category=77226

I ran one on my death race bike & now have one on my 26" mountain bike also. so far the pad wear is looking great. sinple to adapt to a bike also...if your going to go moped speeds use moped brakes i say. :wink:

Agreed. I ran the biggest bicycle rotors and calipers made. The rotors warp like potato chips, the calipers boil and fade, and pads last less than a day of fun.

Put a scooter/motorcycle brake on, and you are likely going to be set for life with never having maintenance and always having rock solid performance.

 

[recumpence]

I agree wholeheartedly. For ultimate racing applications, a motorcycle brake is the way to go.

I am focussed on performance street bicycle setups. I want to achieve the best performance I can with light weight, bolt-on bicycle parts. That is the reason for this new rotor.

Matt

 

[bobc]

I'm mildly interested in all the wavey edges, drill holes etc. in the braking area of the discs. In car applications
drilling for lightness and water escape - (generally just introduces stress raisers) -
grooves to combat gassing (gas from pad can push braking surfaces apart)
To me these all look like sharp edges to wear the pads really fast..... My prejudice is that these are all fripperies to impress the uneducated... any evidence of braking improvements resulting?
PS angling the spokes to put the outside of the disc in tension - great tip, seems very obviously a good idea! I never gave much thought as to which way round to put on a disc rotor before....

 

[recumpence]

Bob,

I am not a disc brake engineer. However, I have found drilling of the rotor face tends to reduce pad glazing quite a bit. I think it looks cool. But, I have run solid discs and drilled discs and slotted discs. The solid discs glaze the pads more easily. Also, the holes cool the discs better.

That is my personal experience. I have run many different discs looking for the best option. The larger the diameter, the better they hold up. But, there may be a limit there. We shall see.

Matt

 

[Thud]

Hey guys,
As I understand it, the wavy edges are striclty for adding external area to the diameter of the rotor for cooling...& to controll directional expansion when heating up.

Holes/slots in the rotors allow any dirt or crud a place to fall into as the rotor is pinched with the calipers. Properly chamfered they pose no apreacable wear to the pads. It actually extends the life of the rotor & pads working in concert.

Saw blades actually are sectioned along the edges for the same reason. old school blades have a relief hole at the end of the slots to stop crack propigation & then the hole is bunged with alumn or brass to keep the blade from whistling at the rpms saws run at. lately the fad is laser cut thin lightning bolt patterns with no bung.

 

[recumpence]

Thanks for the info, Thud!

I am still learning, though I am getting old. :wink:

Matt

 

[bobc]

Interesting posts:
Matt, my recollection was that glazing was usually due to disc contamination with hydrocarbons, be it oil from the wheel bearings, or the road, or the hydraulic system - in conjunction with heat of course... Allegedly the worst culprit is detergents used for cleaning..... The big disc on the small wheel will be well in the zone for splashes from the road... (and you're not allowed to clean it.. ;^)
Thud - the wavy edges reduce the disc area (far bigger impact on the area of the disc faces than the edge). And you won't get more wind because remember the disc is moving sideways through the air, the rotation is almost negligible. Sounds like somebody's marketing bull to me I'm afraid..... And I've never seen a bike disc chamfered in any way (but I've never seen an expensive one...). The chamfer would have to be significant size or it would quickly disappear due to wear. And wouldn't a chamfer actually feed contamination into the disc/pad interface rather than scrape it off?
I looked into car disc brakes for a project I did last century (put a rover V8 in a mazda mx5) & there was SO much b******t marketing in the car world to separate novaboys from their money...
1st rule - you can't believe anything a manufacturer or dealer says - they are only interested in your wallet. And they lie through their teeth, all of them, all the time.
2nd rule - you can't believe anything a 1st hand user says either; they've just shelled out hundreds so they HAVE to believe it's better than it really is. To a ludicrous degree - we all do it...
3rd rule - you can't believe anything a magazine article or journalest writes; they are always in somebody's pocket, or have a vested interest or hobby horse to push.
What can you believe? Nothing & nobody - just a few individuals who have earned your trust ;^)
The info I ended up believing concerning car discs was 1) steer well clear of drilled rotors 2)some pads can benefit from grooves if you drive like a lunatic, mostly plain discs are best

 

[vanilla ice]

I'm with bob on the fancy pants disc edges. The road racers I've talked to use cheapie blank rotors, which makes sense if you view them as a disposable. And their brake pads are not cheap. So its not that they are unwilling to spend money where it matters.

The angled edges and holes do LOOK cool..

 

[oatnet]

Giant Disk , Nice work.

Tell them, straight spokes! They can come off the hub at an angle, but if the spokes have a curve, its asking for the rotor to fold.

%$*$%^$%$(^^& !!!!!

I guess the 8" disks I bought for a current project are a fail. Thanks for the schooling Luke, I'd much rather find out here than on a ride. Guess I'll be binning these:


These look straighter... maybe I'll go with this instead. Although the edges of the spokes have a curve to the edges, I can draw a straight line through them, does this one look OK?

 

[liveforphysics]

Interesting posts:
Matt, my recollection was that glazing was usually due to disc contamination with hydrocarbons, be it oil from the wheel bearings, or the road, or the hydraulic system - in conjunction with heat of course... Allegedly the worst culprit is detergents used for cleaning..... The big disc on the small wheel will be well in the zone for splashes from the road... (and you're not allowed to clean it.. ;^)
Thud - the wavy edges reduce the disc area (far bigger impact on the area of the disc faces than the edge). And you won't get more wind because remember the disc is moving sideways through the air, the rotation is almost negligible. Sounds like somebody's marketing bull to me I'm afraid..... And I've never seen a bike disc chamfered in any way (but I've never seen an expensive one...). The chamfer would have to be significant size or it would quickly disappear due to wear. And wouldn't a chamfer actually feed contamination into the disc/pad interface rather than scrape it off?
I looked into car disc brakes for a project I did last century (put a rover V8 in a mazda mx5) & there was SO much b******t marketing in the car world to separate novaboys from their money...
1st rule - you can't believe anything a manufacturer or dealer says - they are only interested in your wallet. And they lie through their teeth, all of them, all the time.
2nd rule - you can't believe anything a 1st hand user says either; they've just shelled out hundreds so they HAVE to believe it's better than it really is. To a ludicrous degree - we all do it...
3rd rule - you can't believe anything a magazine article or journalest writes; they are always in somebody's pocket, or have a vested interest or hobby horse to push.
What can you believe? Nothing & nobody - just a few individuals who have earned your trust ;^)
The info I ended up believing concerning car discs was 1) steer well clear of drilled rotors 2)some pads can benefit from grooves if you drive like a lunatic, mostly plain discs are best

BobC, you're spot-on.

Plain rotors are best for performance in clean conditions. Holes/slots can help to clear mud/etc in sloppy conditions, and a very long time ago the holes could give the gasses the pads were boiling off a place to go (which is now not needed with modern pads).


The wavy edge thing was originally fairly slight and a curled around flattened sinewave profile to balance pad wear as the outside spins faster than the inside so the pads don't wear perfectly evenly on a small-ish diameter rotor with a large wear area radius vs total radius. It was tried for a few years, then rotors for all real performance applications went back to round on the outside. Then marketing people started making all manor of awful designs with all sorts of detrimental and pointless patterns in the outside of the rotors and people bought them up like candy.

Do NOT NOT NOT counter-sink the holes or slots in a rotor!! This makes a ramp to feed whatever material right up under between the pad and disk, which is exactly the whole goal to avoid. Sometimes you see a countersunk edge on super cheapy stamped rotors because they are prone to having the folded edge from the stamping rise up and shred the pads after a few heat cycles. A good rotor will always have a clean sheer edge.