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Discussion Starter · #1 ·
I got a new gary Fisher Rumblefish II a few weeks ago and it has been on about 3 rides of 3 hours or so thus far. After my second ride, I noticed a pronounced pulse in my front brake. I took it to the LBS and they said everything looks in order (nothing bent essentially).

I have tried to gradually apply the front brake on a recent road ride in an attempt to break it in, but thus far to no avail.:madman:

I love the bike,but the shop where I bought the bike is > 3 hours away so I would like to exhaust all possible options before I spend another day in th car down and back. :confused:

Thoughts? Thanks very much!
 

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SoCal mtbr
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Is the rotor warped at all? If you don't have a repair stand flip your bike upside down and spin the front wheel to see if the rotor rubs on the pads. If so you might need to true the rotor.
 

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Discussion Starter · #3 ·
The rotor is perfectly straight. The bike has not been wrecked or laid down (yet). That was the first thing the LBS looked at.
 

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SoCal mtbr
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Ok, I understand your bike shop checked but have you? I'm not trying to say your bike mech doesn't know what he's doing but it's always good to check for yourself. No one is going to be more critical of your bike than you are and it's always good to know how to fix your own stuff especially if your bike shop is about 3 hrs away....If everything is strait and true the next thing would be to check the pads to see if there's any debris and chunks missing then if that's all good try a brake bleed. Actually the first thing you could try is to re-align you brake caliper (see Avid's site for instructions) I can't think of why your brakes would do that unless there's something wrong with the rotors, brake pads, or maybe air in the system. I have the same Elixir R's on my bike and couldn't be more happy with them.
 

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Discussion Starter · #5 ·
Honestly, I have not checked as I feel I am "out of my depth." You are absolutely correct though in that I need to learn how all of the components work. I will take your advice this eve and check it out. I will get the instructions first though. ;)
One of the reasons I got such a good bike (IMO at least) is for the compents it included - read I did not want ANY problems - but alas life is not perfect.
Thanks very much for your help!
 

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Pulsing has more to do with the physical setup of the caliper and rotor than the fluid within the system. A complete bleed of the system is redundant (and probably a waste of money) as the brake system is brand new. I've seen avid brakes on new bikes in my shop over filled, under filled and in rare cases have a little air in the system, but none of them required a full bleed to fix.

In some situations certain rotors do not work well with certain calipers (due to the way the brake pads contact the braking track). I had some strange pulsing issues with hayes strokers on the rear of one of my bikes, I used a couple of thin washers as shims and moved the brake out about a mm or two and the pulsing went away. I would start with arashi's suggestion of recentering calipers and checking the pads, at the most you'll need a 5mm allen key, a couple business cards, the internet (for reference of course) and beers.


Deep.
 

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Discussion Starter · #7 ·
Thanks very much. I printed off the manuals from the AVID website and wil look very closely at the set up this eve, I still have a few Celebration Ales left in the fridge for "medicinal" purposes of course.
Thanks again - very much appreciate the help!!!
 

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If you have a micrometer (or access to one), measure the thickness of the rotor in several places around it. An area that is .003"-.004" thicker will be felt as a pulse.
 

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Discussion Starter · #9 ·
Strangely, the pulse was not felt on the first two rides - just after the 2nd ride.
The whole things is a bit odd - just want it to go away so I can ride without being jarred.
I have some fine woodworking measuring tools - will see if I can use one of those.
Thanks very much.
 

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alcohol

May I suggest cleaning the rotors with a clean rag and some isopropyl alcohol? I find it's usually some grease on the rotor, even something as small as a fingerprint.

May I also suggest whiskey? As long as we're on the subject of booze...
 

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Meh.
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Leprechaun19 said:
Strangely, the pulse was not felt on the first two rides - just after the 2nd ride.
The whole things is a bit odd - just want it to go away so I can ride without being jarred.
I have some fine woodworking measuring tools - will see if I can use one of those.
Thanks very much.
If the caliper was not alligned properly to start with, the uneven wearing of the pads could cause this problem. Parts could have also shifted as things settle in.
 

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Did you ever figure out what the problem was with your front brake? I have a new bike with Hayes Stroker Ryder hydraulics, and am having the exact same problem. The first few rides were great, then the front brake just started pulsing/grinding and stopping really rough. I took it back to my bike shop and they said the same thing "it is normal, and seems fine". They made a couple small adjustments and wiped the rotor. When I got it home to test, it was better but it still had the issue. Let me know if you figured it out.
 

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Discussion Starter · #13 ·
No, I never did. I wrote the shop where I bought the bike (> 3 hours away) and they said it just needed to be broken in. I took it to the LBS and they said hte pads had oil on them and replaced them. Still same problem.

I spent 2 hours working on the problem myself. The rotor was a tiny bit warped - straightened that out and the problem is a bit better but has NOT gone away.

Frankly, I am growing weary and a bit pissed off about the whole thing. I am thinking of just replacing the entire front brake assembly.

IF you find out a solution, please let me know.

Thanks,
Patrick.
 

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Unfortunately, this seems to be a common occurrence with Elixir's. I have the CR's on mine and they are very loud. SRAM has issued a recall but it appears none of the LBS's know about it. I had to email the link about the recall to my lbs who then phoned SRAM. Here's the sh*tty part - your LBS has to send SRAM the parts (rotor and pads in this case), then SRAM will send back the 'New & Improved' parts back. In other words, you'll be without your bike for an indefinite amount of time. No word on wether the new parts have fixed the problem.

I've decided to take the pads out and 'deglaze' them to see if the problem goes away. On the bright side, the brakes still function as they should - they're just annoyingly loud.

You can read more about the recall here
 

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I have the exact same thing on the front of my new bike. First time I have had Avid's and it is frustrating.

I took it into the LBS first - they replaced the rotor with a Shimano one - still the same issue. I have used alcohol on the rotor and pads - still the same thing.

The front has been like this since day one.

The new problem that has just cropped up is a really loud squeal from the back - but more than the sound it is vibrating the whole bike so bad that you can not use the rear at all right now. I have done all of the normal tricks - but to no avail.

Kirk
 

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Are any of these bikes running 185 or 200mm brake rotors? I had a 185 on the front of my rigid SS, and NOTHING would quiet the brake. I am a 30+ years experienced mechanic and I could not get the front brake to quiet down - cleaning, even ran the rotor with a high-speed wire wheel against a flat steel surface before cleaning it with alcohol and scotchbrite. A while back, I replaced the rotor with a (used) 160 that I had laying around. Changed the adapter and used the same caliper, same pads, etc... The problem went away and has not come back. A friend with a Yeti running 200mm rotors was having the same sort of problem - he changed rotors down to 185mm, and the brakes were silent.

It is quite possible that on many bikes a harmonic resonance is set-up with the brakes as the caliper tries to lever around the fork or stay - and it could be the rotor size isn't all that does it. It could be the pattern of the venting/machining on the brake sweep area, or a number of things - trying different rotors would be the first suggestion, with a different rotor size being the start, if you have something larger than 160 or 185 on there right now - see if you can have that tried as a test. Being 3 hours from your shop, it may be less expensive to go on-line and buy a 160mm rotor and avid adapter if that will do it. I know that the Rumblefish comes with a 185 Fr rotor - correct? Hope that if nothing else works, this helps.
 

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I have the pulsing problem in a 2week old Giant Reign 1, with Elixir R.
Will try to take it to LBS this week. Was hopping something was bedding yet, as I took just a couple of rides with it.
Now that I read this I'm getting worried. Will post updates
 
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