EMTB brake noise solutions? Is this normal?

[PDoz]

His rotor was replaced with Shimano sm-rt86m 180mm. Just to let you know.

That's impressive lbs support - replacing a cheap tekro rotor with a good quality shimano ice tech?

I gad a similar exoerience when my giant was new - the chainring failed and the lbs upgraded me to raceface ( that is still on the bike! ) . It probably cost the dealer $50 but was a well appreciated gesture of support

 

[Stefan Mikes]

That's impressive lbs support - replacing a cheap tekro rotor with a good quality shimano ice tech?

Middle sized Polish city of Częstochowa is (for reasons unknown to me) the place with the biggest number of LBS, many of them carrying leading bike brands. The Częstochowa TREK dealership is the largest in our country. The owner surely knows what providing excellent service means to his sales. He is also good with the commercial stuff such as discounts and financing. For these reasons, Daniel chose Trek, and won't return to either Giant or Specialized in his city, even if his wife rides a Liv e-MTB, and his son owns a Specialized Enduro.

 

[PDoz]

Middle sized Polish city of Częstochowa is (for reasons unknown to me) the place with the biggest number of LBS, many of them carrying leading bike brands. The Częstochowa TREK dealership is the largest in our country. The owner surely knows what providing excellent service means to his sales. He is also good with the commercial stuff such as discounts and financing. For these reasons, Daniel chose Trek, and won't return to either Giant or Specialized in his city, even if his wife rides a Liv e-MTB, and his son owns a Specialized Enduro.

Great lbs are priceless , but that makes it hard when they can't get what you want. My giant dealer can source norco and merida , I waited a long time hoping either of those would release a light emtb before giving up and buying a second hand specialized. We have 3 spec dealers, one of them I have a reasonable relationship with but he can't source anything. The other 2 stores leave me feeling dirty.....

 

[Dallant]

His rotor was replaced with Shimano sm-rt86m 180mm. Just to let you know.

Interesting. My local Trek guy (a mountain biker) was suggesting a smaller rotor as a replacement. His opinion is that the 203 is just too big and may continue to have issues like this. I‘m hoping he’s wrong.

 

[PDoz]

Interesting. My local Trek guy (a mountain biker) was suggesting a smaller rotor as a replacement. His opinion is that the 203 is just too big and may continue to have issues like this. I‘m hoping he’s wrong.

I'd be surprised - you have rock shox gold 35's? They are rated up to 220 mm rotors, so they shoukdn't be twisting.

35 Gold RL - FS-35G-RL-A2 - RockShox

35 Gold RL, FS-35G-RL-A2, RockShox. With bigger bikes, there come bigger demands. Thankfully, we created the 35 to offer great performance and value. Whether you are e-powered or au nat...

www.sram.com

Perhaps he thinks the rotors are flexing under pressure ? This would only be an issue with badly adjusted brakes or faulty calipers ? I guess going back to 180's means you get rid of the spacer between fork and caliper so reduce the number of things for a mechanic to adjust wrongly?

 

[Dallant]

I'd be surprised - you have rock shox gold 35's? They are rated up to 220 mm rotors, so they shoukdn't be twisting.

35 Gold RL - FS-35G-RL-A2 - RockShox

35 Gold RL, FS-35G-RL-A2, RockShox. With bigger bikes, there come bigger demands. Thankfully, we created the 35 to offer great performance and value. Whether you are e-powered or au nat...

www.sram.com

Perhaps he thinks the rotors are flexing under pressure ? This would only be an issue with badly adjusted brakes or faulty calipers ? I guess going back to 180's means you get rid of the spacer between fork and caliper so reduce the number of things for a mechanic to adjust wrongly?

Just to be clear, there are more than one Trek shops involved in this story. My local Trek guy (where I bought both of our Allant+7 bikes) took a shot at adjusting the Rail 5 (which I bought at a large sports chain) brake but it still made the noise. That’s when he told me he thought it was too big. The Rail is now at another of the same sports chain that is a Trek dealer in a larger city and they are the ones who called Tekro for the same size replacement. It’s only an hour away and was on the way to where we went over last weekend.

 

[m@Robertson]

The intermittent nature of the problem and the fact they are bike-standard thickness do seem to point to the rotor being the problem.

Those Tektro brakes use 1.8mm rotors so not too many options for extra strength, unfortunately. Its unfortunate Trek did not use one of the Tektro brake models meant for ebikes as they also use the beefiest rotors on the market - the Tektro Type 17. 2.3mm thick and they seem impervious to warping or even wearing out.

I looked for a type 53 rotor from Tektro and didn't find one. there is a type 35, which is a center-lock 203mm that looks sturdy.

 

[Dallant]

The intermittent nature of the problem and the fact they are bike-standard thickness do seem to point to the rotor being the problem.

Those Tektro brakes use 1.8mm rotors so not too many options for extra strength, unfortunately. Its unfortunate Trek did not use one of the Tektro brake models meant for ebikes as they also use the beefiest rotors on the market - the Tektro Type 17. 2.3mm thick and they seem impervious to warping or even wearing out.

I looked for a type 53 rotor from Tektro and didn't find one. there is a type 35, which is a center-lock 203mm that looks sturdy.

I looked too and couldn’t find one. Maybe they transposed the numbers.

 

[Dallant]

The intermittent nature of the problem and the fact they are bike-standard thickness do seem to point to the rotor being the problem.

Those Tektro brakes use 1.8mm rotors so not too many options for extra strength, unfortunately. Its unfortunate Trek did not use one of the Tektro brake models meant for ebikes as they also use the beefiest rotors on the market - the Tektro Type 17. 2.3mm thick and they seem impervious to warping or even wearing out.

I looked for a type 53 rotor from Tektro and didn't find one. there is a type 35, which is a center-lock 203mm that looks sturdy.

I’m not a fan of that Tekro web site.

 

[cc_math]

I’m not a fan of that Tekro web site.

If the new Tektro rotor doesn't solve your issue, tell your dealer you want a Shimano RT76 rotor (as comes on a Rail 7); it has an aluminum carrier and is less prone to warping.

 

[m@Robertson]

I’m not a fan of that Tekro web site.

Yeah you literally have to know where you are going to even find the rotors.

 

[fooferdoggie]

you dont need the same brand rotors. just get any good brand.

 

[PDoz]

you dont need the same brand rotors. just get any good brand.

Just be careful at the cheaper end of the spectrum, eg shimano alivio rotors are only compatible with resin pads ( they squeal badly with sintered)

ps, thanks - you triggered a memory that may have solved my wifes braking issue. Her norco scene carries on like a tortured pig and has evil tekro brakes. I've been meaning to source a new second hand upgraded brake system for a while - eg people with soecialized fashion sense seem to upgrade from the stock sram guides before even using them, so they are dirt cheap and infinitely better than the junk on my wifes bike. I just need to check her forks can cope with those forces.

 

[m@Robertson]

I have measured brand-new Avid rotors that came in at 1.4mm. I have heard they are manufactured more thinly on purpose, or at least they were at one time. I have not used BB5's or BB7's in years so things may have changed. Either way make sure the rotors are up to spec, and put your (measuring) calipers on them every few months to see if you've worn out your set. They don't look any different but thin rotors beyond the brake caliper's acceptable wear point can lead to pistons pushing too far out and then leakage could follow. My Maguras need a 2.1mm rotor and the industry-standard 1.8mm is when Magura says they are too thin and its time to replace. Some Tektro ebike calipers specify 2.3mm rotors.

 

[fooferdoggie]

sometimes it is the caliper. on my magura mt4 I tired metallic pads the noise was not too bad till they got wet then they warbled and screeched. but even dry they did not stop warbling. had to go back to the regular pads. but those same rotors are fine with my shimano tx 4 piston and metallic pads. they are far quieter then they ever have been with the mt4's

 

[Dallant]

Talked with the Trek guys working on the Rail 5 again today and they mentioned that Tekro intimated something like the Tekro brake set that Trek chose for the Rail 5 isn’t beefy enough, in their opinion. Hence, the supposedly beefier rotor.
Trek guys also mentioned that they also couldn’t find the 203-53 rotor on Tekro’s web site and speculated that it may be a part that is unavailable to the general public. I first ran into something like this when my local Trek guy ordered an adjustable handlebar stem for my wife’s Allant+7 Lowstep. It wasn’t available to the general public either.

 

[Dallant]

So…
Trek techs (not my local guy) set to figure this out and when adjustment just wasn’t working they called Tektro. Tektro said they’ve seen this issue and sent out a 203-53 replacement under warranty. Trek guys did the swap and also threw in a shock adjustment and wheel check, all under warranty. A quick parking lot ride showed success in a silent rotor. Thanked them all for their efforts and took it home. I’m also impressed with Tektro customer service for seeing/acknowledgment of the issue and replacing with beefier design. This is the kind of customer service I bought Trek for!
Yesterday I spent about 15 minutes bedding in the rotor with the existing brake pads and again, silence. Today will be a big test as I’m taking the Rail 5 back to some very basic dirt/grass trails and am crossing my fingers. Pics are of original 203-19 rotor on wheel, new 203-53 in plastic, 203-53 freshly bedded-in on bike.

 

[Dallant]

Spent the morning riding on pavement and several rough trails. Approximately 15 miles and no noise!

 

[TNC]

Interesting following your issue here, Dallant. I have the same HD-M745 4-piston brakes on my Santa Cruz Nomad with a BBSHD. I already had 203mm rotors on the bike for a long time and had a store of rotors in the parts bin, so I didn't buy the Tektro rotors. The front rotor is an old Hayes that sat in its original plastic for years, while the rear is a low use Avid rotor. The Hayes is 1.9mm thick as well as the Avid. I had noticed the HD-M745 rotors were 1.8mm while the HD-M750 rotors were 2.3mm. Both HD-M745 and HD-M750 brake sets are 4-piston...use the same master cylinders, same pads (equal Shimano fit), but use slightly different calipers. Neither brake set is actually more powerful, but it is interesting that Tektro fitted the 2.3mm rotor with the HD-M750's.

Now, all that said, the HD-M745's are excellent brakes. There must be something in the rotor design from Tektro, however, that is requiring a thicker rotor for these powerful 4-piston brakes. I say that because my HD-M745's are running fine on the old Hayes and Avid rotors...no squealing on braking, no drag off the brakes, and no sound while rotating freely. It must come down to the rotor material, the design of the rotor spokes/holes, or something else. I work at a bike shop, and I've seen mismatched brand rotor and brake sets over years without issue. I've never really concerned myself with having the exact brand rotor to the same brand caliper...as long as hardware and rotor size was appropriate.

Barring a warped or tweaked rotor, your situation reminded me of some instances where pressure in the hydraulic system caused a very slight rub between rotor and pads. This could be from not performing a vacuum pull on the syringes as recommended by some brands and models, or someone not insuring the caliper pistons were fully retracted during service or assembly when new. Regardless it is evident that Tektro makes a thicker rotor for their 4-piston setups, and that probably indicates something in their design. I'm glad they worked it out for you and under warranty. Trek is usually pretty good about that. The shop I work at primarily sells Trek and Specialized.

 

[Dallant]

Interesting following your issue here, Dallant. I have the same HD-M745 4-piston brakes on my Santa Cruz Nomad with a BBSHD. I already had 203mm rotors on the bike for a long time and had a store of rotors in the parts bin, so I didn't buy the Tektro rotors. The front rotor is an old Hayes that sat in its original plastic for years, while the rear is a low use Avid rotor. The Hayes is 1.9mm thick as well as the Avid. I had noticed the HD-M745 rotors were 1.8mm while the HD-M750 rotors were 2.3mm. Both HD-M745 and HD-M750 brake sets are 4-piston...use the same master cylinders, same pads (equal Shimano fit), but use slightly different calipers. Neither brake set is actually more powerful, but it is interesting that Tektro fitted the 2.3mm rotor with the HD-M750's.

Now, all that said, the HD-M745's are excellent brakes. There must be something in the rotor design from Tektro, however, that is requiring a thicker rotor for these powerful 4-piston brakes. I say that because my HD-M745's are running fine on the old Hayes and Avid rotors...no squealing on braking, no drag off the brakes, and no sound while rotating freely. It must come down to the rotor material, the design of the rotor spokes/holes, or something else. I work at a bike shop, and I've seen mismatched brand rotor and brake sets over years without issue. I've never really concerned myself with having the exact brand rotor to the same brand caliper...as long as hardware and rotor size was appropriate.

Barring a warped or tweaked rotor, your situation reminded me of some instances where pressure in the hydraulic system caused a very slight rub between rotor and pads. This could be from not performing a vacuum pull on the syringes as recommended by some brands and models, or someone not insuring the caliper pistons were fully retracted during service or assembly when new. Regardless it is evident that Tektro makes a thicker rotor for their 4-piston setups, and that probably indicates something in their design. I'm glad they worked it out for you and under warranty. Trek is usually pretty good about that. The shop I work at primarily sells Trek and Specialized.

Thanks for the response! To my knowledge both the original 203-19 and the replacement 203-53 are 1.8. In fact I asked the Trek tech to measure the 53 with a caliper, just out of curiosity. The big difference is the design is beefier with much more support in the center. Probably heavier but I’m far from a weight monger! There were 3 different techs who adjusted that front brake with the 19 and it just always ended up making that raspy noise whether I was actually braking or not!