Avid Mech/Giant Users and 1st report on Fibrax pads
I have Avid Mechs on my Giant Warp DS1 '03.
I have had problems with my rear rotor warping and fast pad wear. The front runs quietly as expected.
I thought it was due to poor centering and torqueing and it probably was. But just working on trueing the rotor, I noticed the caliper sits too high on the rotor so the pads have a gap like two or three milimiters where the pads do not bite the rotor.
I was wondering why my rear brake had been heating up so much on long descents and I finally got the answer. As the pads do not bite all the rotor, the effective braking area gets reduced and more heat is generated.
By the measures I would say this is either a leftover from when the Avids were 165mm rotor or Giant used the wrong adapter on my brakes.
I can only blame it on Giant. Chances are the IS mounts are too far from the axle or Giant used a 165mm rear adapter instead of a 160mm adapter.
I guess the problem is easily solved by either using a 165mm rotor or getting a 160mm adapters. I could get rid of some of the CPS washers and play with it a little. Some other would say "just ride the thing and shut up" but is kinda annoying and it for sure gives me problems as trails in the sorrounding are all way up to come down again so each time I climb 17kms up it means I gotta go 17kms down and obviously it puts a lot of stress on either brake but rear suffered heavy warping.
Anyone has had this problem... am I beating a dead horse?? I'll take the bike to the dealer and see what can I get as the bike is now almost eight years old and they do not hadle Avid.
For the Fibrax pads... I haven't bedded in them yet but I can tell you that they require some material to be removed in order to fit the separating spring. Pre-02 owners should get away with the pads as they are.
FYI, the adapter never changed, just the caliper. The original 165mm calipers and current 160mm calipers both use the same adapter.
Further clarification - I don't believe the caliper changed (they did modify the aesthetics of it, but this isn't related to going 160mm)), however the spacers on the CPS were reduced slightly to solve the problem. If you contact Avid they will send you the right spacers to resolve the problem.
Originally Posted by Speedüb Nate
The different sized spacers were an answer to the problem of folks who had to purchase adapters to run the larger 185mm and 203mm rotors, since Avīd only made the larger rotors available at about the same time the new calipers came out.
Originally Posted by Roy
By using different thickness washers, Avīd made the initial batch of 185 and 203 adapters to fit the v.1 calipers, and thicker washers were used to fit the v.2 calipers.
So, yes, the 2.5mm difference between the 165 and the 160 was all in the caliper and not in the washers or adapter.
I thought that the newer calipers for the 160 rotor came with the smaller spacers on the CPS; the older calipers had the larger spacers for the 165. And that this resulted in the calipers being identical, but you had to change the spacers to go between the 2 rotors? i.e. if you used the same spacers on both v1 or v2 calipers, they had the exact same spacing.
Originally Posted by Speedüb Nate
My understanding that the reason the adapters were off is because the adapter bolts to the CPS itself. Again, if you changed the spacers on the CPS appropriately, the v2 would work the same as the V1. And if you used the exact same spacers on the CPS (with a v1 or a v2 caliper), there would be no difference in reach on the v1 or the v2 caliper.
The bike is not 8 years old... it's only 8 months old.
I don't know. To be true I'm really confused now you guys are telling me this. Caliper is post '02 for sure, I have another two and one of them is one year older than the one that has the problem and they all are the same (all of them have the BBDB MTN sticker, typical of post-'02 calipers) so the problem could be the washers. I measured the IS mounts and they are correct (51mm spacing and radiuses are correct, thanx Magura Site for the info!!).
Problem is at the "Avid Interface" but anyway Giant should not get the bike out without noticing it. I understand this a very subtle stuff to notice, but hey... mixing things up is not correct at all. I can bet there are more people out there with this problem as the assembling guys should not measure each and every bike they let out and they just take the parts sent from Avid and assemble the stuff. So at the end Avid should get the blame.
Let's see who will solve it. I don't want to pay for an assembly mistake.
I promise you, it's not the CPS washers. You can call Avīd directly at (877) 525-2843 and verify this.
Is it possible Giant installed some non-Avīd washers that are a few millimeters thicker than the normal ones? Veryfy you have just the two CPS washers and nothing else between the caliper and the adapter. Any (improbable) chance you somehow got stuck with a smaller than 160mm rotor?
The 3mm thick spacer washers were used only for the 185 and 203mm kits, and they were in combination with the concave/convex CPS washers.
You'll notice if you purchase an Avīd adapter, it's listed as "Avīd 160/165" and only comes with one set (one size) of CPS washers.
As further indication, consider this: To fit a 185mm rotor to my Manītou fork, I required a 72mm post mount adapter. Unlike the IS adapters which were designed to be used with both the v1 (no spacer) and v2 (w/ spacer) calipers, the post mount adapter was designed only with the v2 caliper in mind.
I contacted Avīd for a workaround to use my v1 caliper. Avīd politely told me "No dice." I'd either need to grind the adapter down 3mm, or do away with the CPS stack, or I suppose I could have switched to a 190mm rotor.
In any case, I instead sprung for a v2 caliper off of ebay and I'm a happy camper.
Bottom line, the difference lies only in the caliper, not in the CPS stack, and not in the adapter. Paul at Avīd will be happy to verify this if you give him a call.
I already wrote Avid but if their reply does not "fit" my needs I'll call them (I'm in Mexico and the call should not be on the cheap side).
I'll compare the CPS washers at the rear with the one in the front and eliminate this possibility. I'll check rotor diameter and compare the calipers measures to isolate the problem.
At this point, Avid already "owes" me a rotor and a set of pads... and who knows, maybe a caliper. I've heard Avid has a good customer support...I just hope they extend their good customer support well below the border. Most manufacturers "play dead" when they hear Mexico.
Well.... first off I would listen to Nate on the washer stuff as I'm pretty positive he's right and I'm wrong.
Originally Posted by Warp2003
Second, you mentioned you have another set of Avids, so slap the rear from the other set on and see if you have the same problem. If they are identical, then compare rotors as mentioned and see if they are identical. Compare the adapters between the 2 sets and see if they are identical. Finally, compare the CPS between the 2 sets and see if they are identical.
Third, I don't know what the spacing would be if you had a front caliper in the rear but this would be the only other error I can think. Other than the rotor being the wrong size (and thus out of spec), or their adapter being out of spec, I don't see how this issue could be Avid's fault.
Fourth - it is possible your frame is out of spec for the disc tabs. If you can borrow someone elses 160 rear rotor/caliper (say a hydro) and see if it lines up, than I would say it is something with your Avid hardware. If it lines up with the same problems I would say your frame is out of spec.
A front on the rear would result in a 10mm difference, fitting a 140mm rotor, so that's not going to be it. I don't know where else to look.
Originally Posted by Roy
I was missing the obvious but hopefully this will serve as an advice to others.
I made dedicate measurements (as delicate as can be done without a caliper) and found out everything normal.
I made kind of a check-list and went thru all the stuff again. Finally and in desperation I swapped the new Fibrax pads and got the old Avids in. Voila!! Case closed!! The Fibrax pads have a much bigger area than the Avids and they sit a bit high on the disc.
Difference is like 1mm in the inner dia of the braking surface of the rotor and like 2mm on the outside diameter.
As I mentioned in the original post, I had to remove some material on each side of the pad to fit the Fibrax with the spring and their braking surface is a bit offset upwards. I do not expect a good performance in this conditions as the offset pad will increase overheating ans the effective braking area will be reduced and at least my set of rotors resulted to be warp-prone. Do the math and you'll see this makes a real difference. Uneven pad wear is at hand too.
Some EBC users could have this problem too... Fibrax's look suspiciously similar to the EBC's
Thanks you all... especially you Nate