Zen Photon Pro - Disc Brake Pad Replacement

[Blunoser]

I concur.. The Dorado and Orion name seem to be interchangeable and are very similar visually. There is a $30 difference in MSRP but I'm guessing that's for the "e" levers on the Dorado.

I have the TRP E.23 caliper which allows for the use of a 2.3mm thick rotor. They have awesome stopping power and greater heat management over the Dorado 4P

They are a bit bulky'r... but I see that as positive.

View attachment 182069 View attachment 182070

They came with the Dorado E725 levers as I don't believe they make an "e" specific lever for the E2.3 Caliper.
A lot of hills riden but none are extreme so with 4000mi on them.. not a single issue. I try to brake back to front as equally as practical so as to not overload one over the other.

The Bafang mid drives all have brake motor cut off built in and I for one appreciate the added safety feature as well as being able to manipulate the feature to get a crank or two in without motor engagement or having to change briefly to neutral PAS.

I think you are both right about the Dorado/Orion variants with the levers being the difference. I was curious as always so went to the Tektro site.. talk about confusing. They have updated most of the lineup to be able to use 2.3mm rotors AND 5mm thick pads. The beefier calipers/pads and rotors add a considerable amount of mass, for better or worse. On an already heavy ebike I say better.
Of course they kept most of the familiar names but changed the model number. Lord. I am interested in running the thicker rotors on my Photon so I hope I get the latest Dorado(now called E730) that allows it. I'm a fairly light guy at ~160 lbs. so I'm sure the 1.8mm rotors will be fine, but why not if I can? Then I can run less aggressive(quieter) pads with no worries. Fingers crossed.

 

[PCeBiker]

I swapped my brake lines to get the rear brake on the left and decided to post some pictures here.


I removed the filler screw and sucked the fluid out.

I was wondered how the brake could operate without a vent hole in the reservoir, especially if the reservoir is completely filled with fluid.

There's a sealed air pocket above the main reservoir that is built into the gasket.
The air in the gasket swells when the brake lever is pulled.

The chambers are separated but have two holes to let fluid or bubbles travel between the chambers.

I'm thinking that it's possible to create enough vacuum in the gasket that the brake pistons get sucked back in after you release the brake lever?

I remember reading about how the brake pistons wouldn't self adjust and stay out as the brake pads wear.
I'm thinking that removing the filler screw and adding fluid occasionally as the pads wear will help keep the pistons from retracting?


It only takes a few pulls of the brake lever and a few seconds bleed the bubbles into the reservoir.

 

[Blunoser]

I'm going to switch my hoses over as well. Been on motorcycles too long to have it the other way. Actually if you had left the cover on(and left the fill/bleed screw in place) and simply just swapped the hoses you would have perhaps only lost one or two drops in the process. As you say the reservoir is sealed and the fluid is hydro locked. If you had a funnel and were lucky, you would be only a quick lever bleed away from done.

The pistons should retract the same way car pistons do, because the seals are square cross section and they move slightly with the pistons as you apply the brakes. Once the pads are worn enough that the piston has to move a lot, then it "slips" a bit relative to the seal and therefore self adjusts. At least that's how it is supposed to work, real life and dirt, etc. Pretty cool how someone figured that out way back when.

 

[PCeBiker]

I'm going to switch my hoses over as well. Been on motorcycles too long to have it the other way.

I hope my muscle memory doesn't get all mixed up.
I'm going to do some rear wheel emergency skid stops in the gravel to help reboot my brain.

Actually if you had left the cover on(and left the fill/bleed screw in place) and simply just swapped the hoses you would have perhaps only lost one or two drops in the process. As you say the reservoir is sealed and the fluid is hydro locked.

That makes sense, I didn't think of that.
I did want to open up the reservoirs and investigate though.
I like to know how things work.

If you had a funnel and were lucky, you would be only a quick lever bleed away from done.

I just added drops of oil into the filler hole.
The funnel isn't necessary, and makes a big mess when you bump it and break it off.

The pistons should retract the same way car pistons do, because the seals are square cross section and they move slightly with the pistons as you apply the brakes. Once the pads are worn enough that the piston has to move a lot, then it "slips" a bit relative to the seal and therefore self adjusts.

That's how my cars brakes work, but there's a vent hole in the reservoir.
If there was no vent hole, the reservoir would create a vacuum as the fluid level drops and that vacuum would pull the brake pistons back to their original "new pad" positions every time you released the brakes.

I suppose that if it was sealed, the reservoir could become pressurized when it heats up and push on the brake pistons enough to make the brakes drag?

At least that's how it is supposed to work, real life and dirt, etc. Pretty cool how someone figured that out way back when.

My street bike had a hydraulic clutch and front brake, but I don't know if the reservoirs had vent holes?

I would think that without a vent hole the lever stroke would increase as the pads wear because the pistons keep getting sucked all the way back in?

 

[Blunoser]

I believe the motorcycles have a bellows in them just like the one in your Tektro seems to(at least that what yours looks like). It shrinks and expands a bit to cover changes in fluid level. I've never had a bicycle master cylinder apart(yet) so I'm assuming that the black rubber thing in yours is a bellows(cushion) of some sort? Anyway, now you have me curious so I'll have to open up one of my brakes to see what's going on in there. I know there are two cups on the main shaft of the master so maybe they somehow prevent the over retraction on the pistons too. Time to dig around a bit online and see how they work. The pads only wear about~1mm each so not really that much change anyway.

BTW, I hope you adapt quickly to reversing the hoses. There is no way I could ride a bike with them the opposite way, especially in slippery conditions such as mud. Been doing right hand is front brake for more than 55 years now, too old to change even if I wanted to.

 

[PCeBiker]

I believe the motorcycles have a bellows in them just like the one in your Tektro seems to(at least that what yours looks like). It shrinks and expands a bit to cover changes in fluid level. I've never had a bicycle master cylinder apart(yet) so I'm assuming that the black rubber thing in yours is a bellows(cushion) of some sort?

Yeah, that's what it is. The "gasket/bellow" was dry on top with a bit of an air gap between the top of the "gasket" and the surface of the reservoir cover.

Anyway, now you have me curious so I'll have to open up one of my brakes to see what's going on in there. I know there are two cups on the main shaft of the master so maybe they somehow prevent the over retraction on the pistons too. Time to dig around a bit online and see how they work.

I can see the two cups working as I squeeze the lever. First fluid shoots into the reservoir from the first hole, then the fluid level drops as the fluid pushes into the brake line.

With the lever released, the reservoir is open to the brake line, and the bubbles rise up out through the tiny second hole.

The pads only wear about~1mm each so not really that much change anyway.

I just measured my new brake pads and they are 4 mm thick including the metal backing plate, and the plate is 1.7 mm thick, so just over 2 mm of pad wear.
So 2 mm X 2 pistons X the circular surface area of the brake pistons should calculate how much fluid is used to push the pads out to the replacement point.

I think that is enough volume to create a vacuum in the brake system if the reservoir isn't ported?

I know that the bellows on my dirt bike fork stanchions had a hole at the bottom to let air in and out.

BTW, I hope you adapt quickly to reversing the hoses. There is no way I could ride a bike with them the opposite way, especially in slippery conditions such as mud. Been doing right hand is front brake for more than 55 years now, too old to change even if I wanted to.

I haven't riden a motorcycle in over 30 years but I didn't do much bike riding since then either.
I know that I didn't have to think about which lever was which when I rode my mountain bike though.

I haven't riden my e-bike yet, but I've already had an issue.
I was moving my bike around inside the house and grabbed the left brake lever to lock the front wheel while I lifted the rear end around a corner and the bike started rolling away from me.

I'll have to practice a lot of panic stops to get my muscle memory set straight, but I'll never know for sure what will happen until I have an actual panic braking event.

I do have a good excuse to do lots of skids in the dirt now. That'll be fun. I'll try to do some skid turns "drifting" or whatever that's called.
That aughta learn me how to feather the right brake. I mean left brake. No drifting the front wheel.

 

[Blunoser]

I have to ask why you are switching the hoses if you don't ride motorcycles anymore. If there is no solid reason you are risking a crash with no upside? Your instincts will likely take over in a panic situation. I won't even go fast on a borrowed bike with the hoses on "backward" as I just don't trust myself to do the right thing without thinking. Old dog new trick sort of thing.

As for the vacuum thing, I've pumped my pistons way out in order to clean them(old Avid brakes) and they never tried to retract. There must be more to it then meets the eye. Maybe the seals have a strong enough grip on the pistons that it only moves with Hydraulic pressure( which might be several hundred pounds) compared to whatever a bit of vacuum can produce? ) It takes a fair amount of force(with a lever) to pry the pistons back in when you extend them like I did.
If you put brake fluid under enough vacuum it will form gas bubbles in it(this is part of the process for Avid/Sram brake bleeds, called "degassing") so I assume the bellows is sized to prevent this?

 

[PCeBiker]

I have to ask why you are switching the hoses if you don't ride motorcycles anymore. If there is no solid reason you are risking a crash with no upside? Your instincts will likely take over in a panic situation.

I don't pedal and ride no-hands more than 75% of the time.
I smoke while riding and I smoke with my right hand.
My left hand is often the only hand to reach for the bars, and I want that to be the rear brake.

As for the vacuum thing,.
There must be more to it then meets the eye.

I'm sure there is. I'm just not seeing it.
Maybe you can post your findings here when you figure out what's going on with your brakes?

 

[Blunoser]

..and there you have it, a solid reason. I figured there was one just didn't know what it was. BTW sweet second use for the bell lol. I will look into the brake thing as you have now piqued my interest. I won't be able to let it go. Might take a while but I'll find out and post it .

 

[PCeBiker]

..and there you have it, a solid reason.

I make it up as go.

BTW sweet second use for the bell lol.

I moved the "ashtray" to the right handlebar as well, so now everything important is done with my right hand. The throttle, the front brake and of course smoking.
It takes both hands and both eyes to light a cigarette in the wind while riding.

I will look into the brake thing as you have now piqued my interest. I won't be able to let it go.

I was tempted to disconnect the brake lever and pull out the plunger to investigate, but I didn't want to break my brakes.

Might take a while but I'll find out and post it .

I can wait.
Maybe I'll look into further this winter when my e-bike and I are hibernating?

 

[Blunoser]

After noticing that you say you ride no hands and not pedalling 75% of time, I have to ask do you lock your throttle on somehow?

 

[PCeBiker]

After noticing that you say you ride no hands and not pedalling 75% of time, I have to ask do you lock your throttle on somehow?

Yeah, I experimented with a few throttle lock designs.
This one is pretty cool. You make it yourself with a plastic coat hanger and a heat gun,..

This is how I locked my thumb throttle.
I loosened up the throttle housing just enough that it would rotate on the handlebar and push into the shifter lever to set a speed/power level,..

My new e-bike has a half twist throttle so I jammed a few slices of margarine container plastic into the plastic bushing to add friction to the movement so it wouldn't spring back when I let go of the throttle,..

That worked for a couple months then it started to slip so I pulled over and wrapped some copper doorbell wire around mechanism to add more friction,..

That worked out Great because the twisted wire became my "speedometer".

The throttle is off right now. The first black line is where the throttle first activates, showing the dead spot in the rotation.
The second black line shows the end of the active spot followed by another dead spot.

The red button turns the throttle on and off, but it sucked because you can't see for looking if it's on or off (in or out), so I covered it with black marker. The red now shows when the throttle is off.


When I bought my first twist throttle, I bought a full twist throttle because I thought that meant you get a full twist of the throttle from 0-100%.
I found out that meant half the grip instead.

PS,.. full twist throttles suck.
The half twist allows you to hold the throttle steady while half your hand is solid on the grip so it doesn't bounce around when you're on rough trails.

With only ~½" of rotation from 0-100%, it's really hard to hold the throttle steady.

There is a Domino throttle available that's ~$100 that is designed for electric motorcycles, so I think it's got more rotation from 0-100%? But I've got almost a dozen throttles already.

 

[Blunoser]

Wow, you’re really into throttling, I am expecting to remove the one on my bike when I get it. I’ll keep it in my tool kit in case I get injured on a ride. Worried that I will rely on it too much and I really want to stay in good shape as long as possible. I had to fight my way back to good health and want to remain active.
I think the motorcycle world has what you are looking for. I remember seeing a lockout device that was a cam clamp arrangement that rests on the brake lever. You could set it at any level and simply override it by twisting the throttle closed.

 

[PCeBiker]

I think the motorcycle world has what you are looking for. I remember seeing a lockout device that was a cam clamp arrangement that rests on the brake lever. You could set it at any level and simply override it by twisting the throttle closed.

Yeah, I remember that one,..

I think it's kinda big and clunky though.

And I just found this one,..
It looks promising.

I like the plastic coat hanger one the most.
It's almost free, stupid simple and it's more satisfying when you make it yourself.

If people think that you bought it, then that's a win in my books. So use a black plastic coat hanger.

My homemade battery brackets look OEM.
Nobody can tell that I made them myself !!

 

[Blunoser]

The one I m thinking of looked more like a seat post quick release with adjustable tension on the cam lever. I never saw one in person so don’t know how well it works.

 

[PCeBiker]

The one I m thinking of looked more like a seat post quick release with adjustable tension on the cam lever. I never saw one in person so don’t know how well it works.

I had one on my motorcycle in 1983.
It was just a small plastic clamp around the throttle housing with a thumb lever to clamp and unclamp it.
It was nice and small and didn't get in the way.

I used it all the time but almost never took my hands off the handlebars because I could be charged with reckless driving.

When I ride my e-bike no-hands at 20 mph, I feel a lot more like a Jackass than a hardened criminal.

 

[Blunoser]

That’s what I remember, that it was small and simple looking. I have a 1976 CB400f that has stupidly heavy throttle springs. I just simply took them off and replaced them with a much lighter one. I never went on long enough rides to warrant a cruise.

 

[PCeBiker]

I took the spring out of my quick throttle while experimenting, but that didn't work out for me.
I bumped the throttle and the bike stood up on the back wheel and fell over on my on my right leg with the throttle stuck on full.

Luckily the bike landed on the derailleur guard and the powered up wheel came off the ground so I could get to the throttle and shut it off.


My latest version of throttle is A Lot safer. It's almost impossible to hit by accident, and it's got a built-in speedometer.

I can still stupid s*it with my throttle, but its harder to do.

 

[Blunoser]

Lol sounds like you might have more crash stories in your future. Hope they fall into the funny category, and not too damaging to body and bike

 

[PCeBiker]

That was my first and worst crash but I do A Lot of falling over.
Over a dozen times on this day alone,..

I've crashed (fell over) three times inside my house and almost wiped out my TV, and I've dropped the bike on the road four or five times.
One time I was practicing locking up my front wheel in the gravel to get a feel for it and dropped the bike.

I'm not and accident waiting to happen. I'm an accident ready to happen.
I hate waiting.