I currently have a Trek Speed Concept which I recently upgraded my Zipp 808 to their new Super 9 rear disc. My 808's are perfect in every way, perfectly trued, no hop, and brakes work like glass. I FOUND THE PROBLEM! READ THE PARAGRAPH IN RED BELOW THIS POST!
However, my Super 9, every time I grab the brakes while slowing down, I can feel a moderate level of the bike pulsating. It is like someone pumping my brakes. Using the same brake pads that were on my 808's, I towed the shoes in slightly by putting a dime while tightening the screw. It helped but not a whole lot.
After placing a call into SRAM's tech support, the customer service reps were very sympathetic and cordial, but after several calls into their call center, it became obvious I wasn't able to find anybody who really has intimate knowledge of these wheels. They simply recited what specs are, .5mm for lateral runout and 1mm for hop and that was all they kept repeating. One rep told me the pulsating if there is any, that is a separate issue which I find hard to believe because from all the forums I have read, a wheel that is out of true will cause pulsating.
SRAM told me I have to go to an authorized Zipp dealer to have them evaluate and then get on their dealer service line and then they would bring the wheel in for an evaluation. Unfortunately, the dealer I brought it to was unwilling to really spend the right amount of time to make careful measurements. He was very dismissive and simply told me Zipp would not warranty this wheel because it is not out of spec. He couldn't even tell me the amount of runout so I bought my own truing stand and made careful measurements.
Long story short, the runout for lateral is about the thickness of a business card and the hop is the same. The left brake track shows slightly out of true but the right rim is perfectly true. This tells me it is probably an imperfection on the brake track itself and not the wheel being out of true.
I called several more bike shops in Chicago, none of their mechanics knew much about Zipp wheels and they told me I have to call Zipp. I then made some calls to some bike dealers in Calfornia, I found one dealer who suggested I use new brake pads and when he learned I ride with the shoes rather far from the rim, he suggested I tighten up the tolerance and that will probably help the pulsating go away.
Anyway, I am upset because I spent almost 3K on this wheel and it is really annoying that every time I brake, it stops and goes. I am going to call SRAM again on Monday and I am not expecting to get too much cooperation because I have been told that as long as the wheel is in spec, there is not much else they can do. If I have the dealer send it in for evaluation, I am not sure they will stand behind their product. Regardless if it is in spec, I expect the wheel not to pulsate period. My 808''s don't
I will keep everybody posted but for now, I think my next carbon wheels will be HED's.
OH MY GOD! I FOUND THE PROBLEM! THE BIKESHOP WHERE I PURCHASED MY TREK SPEED CONCEPT, THEY INSTALLED ONE OF THE BRAKE SHOES BACKWARDS. THERE ARE ARROWS POINTING WHICH DIRECTION THE BRAKE HOUSING AND SHOE SHOULD BE POINTING. HENCE, YOU HAD ONE SHOE THAT WAS POINTING IN THE CORRECT DIRECTION AND THE OTHER WAS BACKWARDS. HOWEVER, WITH THE SAME WRONG SETUP, MY 808'S WERE NOT PULSATING AT ALL. I WAS USING MY OLD 808 PADS BUT THEY WERE WORN DOWN PRETTY BADLY SO I REPLACED THEM WITH THE ZIPP SUPER 9 WHICH BY THE WAY ARE THE EXACT SAME PADS. THE OTHER SIDE WAS INSTALLED CORRECTLY.
ONCE I REPLACED THE PADS WITH NEW ONES, AND HAD BOTH SHOES POINTING THE RIGHT DIRECTION, AND I ALSO DID NOT TOE THEM IN AS INSTRUCTED BY ANOTHER FORUM MEMBER, NO MORE PULSATING AND IT IS SILKY SMOOTH.
THE FEW LESSONS LEARNED FROM THIS:
1. PROBABLY NOT A GOOD IDEA TO USE ALREADY USED PADS ON A NEW WHEEL.
2. BE SURE THE BRAKE PADS ARE POINTING IN THE RIGHT DIRECTION
3. A RIM THAT IS SLIGHTLY OUT OF TRUE AND/OR AN EXCESS AMOUNT OF CARBON LAYUP SHOULD NOT CAUSE BRAKES TO PULSATE. MY RIMS ARE A BUSINESS CARD WITH OUT OF SPEC BUT ONLY ON ONE SIDE.
4. NEVER ASSUME YOUR BIKE SHOP INSTALLED ANYTHING ON THE BIKE CORRECTLY.
5. THE PRELOAD WHETHER LOOSE OR TIGHT DID NOT EFFECT PULSATING. I TRIED IT BOTH WAYS, LOOSE AND TIGHT SAME ISSUE. I HAVE DONE IT RIGHT BY TURNING IT UNTIL IT STOPS, THEN BACKING OFF 1/8 TURN. THERE IS TINY AMOUNT OF PLAY WHERE YOU CAN WIGGLE RIM BACK AND FORTH BUT ONCE YOU SIT ON BIKE, IT IS TIGHT.
I will have to call Zipp and apologize to them for putting them through the paces. Yes i must have drove them nuts but after paying a ton of money for this wheel and then to watch my tribars shake back and forth every time i stop was irksome.
QUESTIONS THAT SHOULD HAVE BEEN ASKED: (NONE OF THE BIKE SHOP MECHANICS THAT I SPOKE TO HAD A CLUE)
1. Are you using your existing brake pads or the new ones that shipped with the wheel?
2. Is your brake pads facing the correct direction?
3. Did you try toe in the wheel or leave them flat?
4. Are your wheels out of true?
New pads would have probably solved the issue from the get go. I wrongly assumed the worn pads would be fine on new wheels. The problem really came down to using worn pads on a new wheel and I do believe the misdirection of the incorrectly installed brake shoe had been a contribuing factor.
However, my Super 9, every time I grab the brakes while slowing down, I can feel a moderate level of the bike pulsating. It is like someone pumping my brakes. Using the same brake pads that were on my 808's, I towed the shoes in slightly by putting a dime while tightening the screw. It helped but not a whole lot.
After placing a call into SRAM's tech support, the customer service reps were very sympathetic and cordial, but after several calls into their call center, it became obvious I wasn't able to find anybody who really has intimate knowledge of these wheels. They simply recited what specs are, .5mm for lateral runout and 1mm for hop and that was all they kept repeating. One rep told me the pulsating if there is any, that is a separate issue which I find hard to believe because from all the forums I have read, a wheel that is out of true will cause pulsating.
SRAM told me I have to go to an authorized Zipp dealer to have them evaluate and then get on their dealer service line and then they would bring the wheel in for an evaluation. Unfortunately, the dealer I brought it to was unwilling to really spend the right amount of time to make careful measurements. He was very dismissive and simply told me Zipp would not warranty this wheel because it is not out of spec. He couldn't even tell me the amount of runout so I bought my own truing stand and made careful measurements.
Long story short, the runout for lateral is about the thickness of a business card and the hop is the same. The left brake track shows slightly out of true but the right rim is perfectly true. This tells me it is probably an imperfection on the brake track itself and not the wheel being out of true.
I called several more bike shops in Chicago, none of their mechanics knew much about Zipp wheels and they told me I have to call Zipp. I then made some calls to some bike dealers in Calfornia, I found one dealer who suggested I use new brake pads and when he learned I ride with the shoes rather far from the rim, he suggested I tighten up the tolerance and that will probably help the pulsating go away.
Anyway, I am upset because I spent almost 3K on this wheel and it is really annoying that every time I brake, it stops and goes. I am going to call SRAM again on Monday and I am not expecting to get too much cooperation because I have been told that as long as the wheel is in spec, there is not much else they can do. If I have the dealer send it in for evaluation, I am not sure they will stand behind their product. Regardless if it is in spec, I expect the wheel not to pulsate period. My 808''s don't
I will keep everybody posted but for now, I think my next carbon wheels will be HED's.
OH MY GOD! I FOUND THE PROBLEM! THE BIKESHOP WHERE I PURCHASED MY TREK SPEED CONCEPT, THEY INSTALLED ONE OF THE BRAKE SHOES BACKWARDS. THERE ARE ARROWS POINTING WHICH DIRECTION THE BRAKE HOUSING AND SHOE SHOULD BE POINTING. HENCE, YOU HAD ONE SHOE THAT WAS POINTING IN THE CORRECT DIRECTION AND THE OTHER WAS BACKWARDS. HOWEVER, WITH THE SAME WRONG SETUP, MY 808'S WERE NOT PULSATING AT ALL. I WAS USING MY OLD 808 PADS BUT THEY WERE WORN DOWN PRETTY BADLY SO I REPLACED THEM WITH THE ZIPP SUPER 9 WHICH BY THE WAY ARE THE EXACT SAME PADS. THE OTHER SIDE WAS INSTALLED CORRECTLY.
ONCE I REPLACED THE PADS WITH NEW ONES, AND HAD BOTH SHOES POINTING THE RIGHT DIRECTION, AND I ALSO DID NOT TOE THEM IN AS INSTRUCTED BY ANOTHER FORUM MEMBER, NO MORE PULSATING AND IT IS SILKY SMOOTH.
THE FEW LESSONS LEARNED FROM THIS:
1. PROBABLY NOT A GOOD IDEA TO USE ALREADY USED PADS ON A NEW WHEEL.
2. BE SURE THE BRAKE PADS ARE POINTING IN THE RIGHT DIRECTION
3. A RIM THAT IS SLIGHTLY OUT OF TRUE AND/OR AN EXCESS AMOUNT OF CARBON LAYUP SHOULD NOT CAUSE BRAKES TO PULSATE. MY RIMS ARE A BUSINESS CARD WITH OUT OF SPEC BUT ONLY ON ONE SIDE.
4. NEVER ASSUME YOUR BIKE SHOP INSTALLED ANYTHING ON THE BIKE CORRECTLY.
5. THE PRELOAD WHETHER LOOSE OR TIGHT DID NOT EFFECT PULSATING. I TRIED IT BOTH WAYS, LOOSE AND TIGHT SAME ISSUE. I HAVE DONE IT RIGHT BY TURNING IT UNTIL IT STOPS, THEN BACKING OFF 1/8 TURN. THERE IS TINY AMOUNT OF PLAY WHERE YOU CAN WIGGLE RIM BACK AND FORTH BUT ONCE YOU SIT ON BIKE, IT IS TIGHT.
I will have to call Zipp and apologize to them for putting them through the paces. Yes i must have drove them nuts but after paying a ton of money for this wheel and then to watch my tribars shake back and forth every time i stop was irksome.
QUESTIONS THAT SHOULD HAVE BEEN ASKED: (NONE OF THE BIKE SHOP MECHANICS THAT I SPOKE TO HAD A CLUE)
1. Are you using your existing brake pads or the new ones that shipped with the wheel?
2. Is your brake pads facing the correct direction?
3. Did you try toe in the wheel or leave them flat?
4. Are your wheels out of true?
New pads would have probably solved the issue from the get go. I wrongly assumed the worn pads would be fine on new wheels. The problem really came down to using worn pads on a new wheel and I do believe the misdirection of the incorrectly installed brake shoe had been a contribuing factor.
Last edited by:
marathonrunner: Jul 8, 17 18:06