Mechanics Quick Question Thread [Ask Questions Here]

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Mechanics Quick Question Thread [Ask Questions Here]
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flag bike2850
O+
Posted: May 24, 2019 at 18:57 Quote
freestyIAM wrote:
dhmtbr777 wrote:
Yeah it’s a known thing you can do. Apperantly not with icetechs

Arm chair engineering analysis of why icetec rotors don't play nice with fire anyone?

because everyone knows ice and fire dont play nice together. there opposites so there you have it!
flag seraph
Posted: May 24, 2019 at 19:17 Quote
I'm guessing it has something to do with the heat treating they do when bonding the aluminum core to the steel outer, or something else sciencey.
flag cyberoptixs
Posted: May 24, 2019 at 20:32 Quote
Duderz7 wrote:
Some Shimano rotors are specific to a certain pad compound, some cannot be used with metallic pads

Well you would think that the RT86 would be able to bed in full metal considering that the finned pads for the saint /Zee only come in resin or full metal
flag OneBanana
Posted: May 24, 2019 at 22:27 Quote
freestyIAM wrote:
dhmtbr777 wrote:
Yeah it’s a known thing you can do. Apperantly not with icetechs

Arm chair engineering analysis of why icetec rotors don't play nice with fire anyone?
Different metals/alloys have different thermal expansion properties. This can be useful in some places - a good example is bimetallic strips (Google has loads of info for the curious).
Icetech rotors are slightly more complex as there are three layers IIRC, but the principle still stands so in exposing them to excessive heat you're potentially going to cause the layers to bend at different rates, potentially warping them and/or causing them to pull themselves apart.
I'm sure they're fine under normal braking temps - certainly hope so as I use them - but my armchair engineering guess is that heating them a lot is not a great idea Wink
flag R-M-R
Posted: May 24, 2019 at 22:50 Quote
OneBanana wrote:
freestyIAM wrote:
dhmtbr777 wrote:
Yeah it’s a known thing you can do. Apperantly not with icetechs

Arm chair engineering analysis of why icetec rotors don't play nice with fire anyone?
Different metals/alloys have different thermal expansion properties. This can be useful in some places - a good example is bimetallic strips (Google has loads of info for the curious).
Icetech rotors are slightly more complex as there are three layers IIRC, but the principle still stands so in exposing them to excessive heat you're potentially going to cause the layers to bend at different rates, potentially warping them and/or causing them to pull themselves apart.
I'm sure they're fine under normal braking temps - certainly hope so as I use them - but my armchair engineering guess is that heating them a lot is not a great idea Wink

Icetech rotors are aluminum sandwiched inside steel wear surfaces.

The expansion rate issue came to my mind, also, but I think the answer is even simpler: the melting temperature of aluminum is 660°C and recrystallization temperature is only 350°C - 400°C. A propane torch burns at over 1000°C: generally not hot enough to melt steel, but aluminum doesn't stand a chance.
flag Hammer48
Posted: May 24, 2019 at 23:01 Quote
Here's a good video on how to bed in your brakes..


https://www.youtube.com/watch?v=vauPWZT9L6c
flag OneBanana
Posted: May 24, 2019 at 23:56 Quote
R-M-R wrote:
Icetech rotors are aluminum sandwiched inside steel wear surfaces.

The expansion rate issue came to my mind, also, but I think the answer is even simpler: the melting temperature of aluminum is 660°C and recrystallization temperature is only 350°C - 400°C. A propane torch burns at over 1000°C: generally not hot enough to melt steel, but aluminum doesn't stand a chance.
Ha, yes, that's a very valid point dude. You can tell I didn't study engineering Razz
flag demo7jumper
Posted: May 25, 2019 at 4:40 Quote
Hey people I have the worst tire fitting rims in the planet , mavic en 427 , I'm trying to fit some tires on them but it is next to impossible I managed to fit a dhf dh casing on the front but the highroller on the back is impossible, any tips ?
I have also broken to tire levers and punctured a tube trying to fit them
flag iffy
Posted: May 25, 2019 at 5:10 Quote
demo7jumper wrote:
Hey people I have the worst tire fitting rims in the planet , mavic en 427 , I'm trying to fit some tires on them but it is next to impossible I managed to fit a dhf dh casing on the front but the highroller on the back is impossible, any tips ?
I have also broken to tire levers and punctured a tube trying to fit them

making shure you push the bead into the well is the thing that helps the most.
flag Trisnpod
Posted: May 25, 2019 at 5:36 Quote
What's going on with this rotor? It came on a bike I bought yesterday and it really doesn't look healthy. Front one looks fine though. The back brake wasn't working very well (cable brakes, cables full of crap and not taking up slack so lever pulls to bar without moving the brake) so perhaps its just cos it hasn't been used recently and has corroded?
Wtf rotor:
photo
Happy rotor:
photo
flag iffy
Posted: May 25, 2019 at 5:42 Quote
Lightly sand the braking surfaces, clean the caliper with IPA and fit some new pads, follow regular bedding in procedure and should do the trick.

disks are just lumps of steel that looks like it was dirty/contaminated and subsequently toasted.
flag R-M-R
Posted: May 25, 2019 at 10:19 Quote
Trisnpod wrote:
What's going on with this rotor? It came on a bike I bought yesterday and it really doesn't look healthy. Front one looks fine though. The back brake wasn't working very well (cable brakes, cables full of crap and not taking up slack so lever pulls to bar without moving the brake) so perhaps its just cos it hasn't been used recently and has corroded?

The owner probably failed to change the pads when the friction material was gone and continued to brake on the backing plate material.

That's too much damage to salvage the rotor. I know it's a shame to lose a fancy rotor, but replace that poor thing.
flag riish
Posted: May 25, 2019 at 10:27 Quote
While we're on the topic- is there a reccomended thickness to replace rotors at? I've had my ice-tecs for a good few years, wondering at what point (if any) the performance starts to drop off.
flag Duderz7
Posted: May 25, 2019 at 10:48 Quote
R-M-R wrote:
Trisnpod wrote:
What's going on with this rotor? It came on a bike I bought yesterday and it really doesn't look healthy. Front one looks fine though. The back brake wasn't working very well (cable brakes, cables full of crap and not taking up slack so lever pulls to bar without moving the brake) so perhaps its just cos it hasn't been used recently and has corroded?

The owner probably failed to change the pads when the friction material was gone and continued to brake on the backing plate material.

That's too much damage to salvage the rotor. I know it's a shame to lose a fancy rotor, but replace that poor thing.

I agree, that rotor looks done. Hang it on the wall for decoration.

As far as thickness, if there's a defined step between the wear surface and the rest of the rotor it's time. It's hard to put a time or miles recommendation on it because of different conditions, maintenance, and braking habits.
flag cyberoptixs
Posted: May 25, 2019 at 17:03 Quote
riish wrote:
While we're on the topic- is there a reccomended thickness to replace rotors at? I've had my ice-tecs for a good few years, wondering at what point (if any) the performance starts to drop off.

I think you are supposed to replace at 1.5mm thickness

 


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