tandem rider

I put a new 203mm Avid rotor on my tandem in Feb. The new Avid rotor has more support in the middle where it bolts to the hub. This support is to keep the rotor "flat" and not as easy to bend. I like our rear disc brake but have had problems with slightly bent rotors that wobble and rub the brake pads. As mentioned above, we clean the rotor ever couple of weeks to get oil and dirt off. I find that isopropyl alcohol works well.

dwmckee

This thread has been really interesting and got me wondering just how close to the limits I am getting with my 160 mm bb7s on my single bike. I have noticed what I thought was the beginning of disc fade on a local hill I ride often. It is steep and windy with maybe 400 feet of vertical. You need to brake almost constantly to maintain reasonable speed (alternating front and rear). I stopped at the bottom of the hill and out of curiosity I pulled out my water bottle and squirted the rotors. They sizzled and steamed to my surprise. They were well above water boiling temp. Does anyone know what temp the rotors hit when you start to get brake fade? I had stock avid rotors and pads have about 400 miles on them so we'll over half life left. I ride near hilly Pittsburgh, PA and weigh about 200 pounds.

rdtompki

Hard to imagine you have anything to worry about. I've descended 3000' total in 8 miles on my Volagi with dual discs. This is a really bad, steep ranch road so when you use the brakes (on the few patches of good road) you've got to use them hard. I had absolutely no sign of brake fade at the bottom. I'm 200 lbs as well. I know my LBS put on other than the stock pads.

twocicle

Are you talking about the G2 or G3 rotor? My guess is the G3.

I have a 10yr old Avid 203mm sitting here and just went shopping for a new BB7. Figured I'd grab the same old rotor but the designs appear to have change to a minor degree. After seeing the G2 and G3 on the SRAM site, did a quick search for reviews of the G3 which found many happy campers. People say their G2 rotors (or older ones like mine) squawked and squealed, but the G3 was quiet, seemed to stop better, and minimal weight gain.

I opted for the G3 this time even though Avid doesn't post that it is BB7 compatible. Strange how minimal that kind of info is from the mfr.

We won't be able to test it for a couple week though.

uspspro

I've been happy with the 203mm G3. I do change it around 1x per year though from warping.

I have been extremely pleased with the EBC Gold sintered pads. They need a little more heat for optimal bite, but really work well once warmed up (when it really matters). MUCH better than the stock organic pads in my experience.

twocicle

When you "change it around" you run it backward from the directional arrows?

tandem rider

[QUOTE=twocicle;14021455]Are you talking about the G2 or G3 rotor? My guess is the G3.

Yes, it is the G3 clean Sweep. Have only ridden it 40 miles so far.

uspspro

Sorry. I meant that I change it approximately 1x per year, as in replace it.

sine

I just swapped our front Avid 203 G3 rotor and pads for Shimano XT ICE (rotor is steel/al/steel sandwich) 203 rotor and EBC Gold pads.

Only 50 odd miles so far.

The bad, rotor arrived out of round. I improved that some but it still has a slight bobble. This is a tough rotor to straighten due to the stiffer al spider.

Brake performance right from the start is about the same as well broken in G3/stock Avid pads. So performance should improve with more miles. Most notable after hard stops is how much cooler the aluminum spider is compared to the Avid G3 rotor. You can touch the XT ICE spider but you risk a burn if you try that on an Avid rotor. I have no hard data to compare actual rotor temps. Most notable after hard braking at the end of a descent is how normal (quiet) the XT ICE disc is. The G3 rotor would make all sorts of noise for 1-2 miles.

Note for anyone considering XT ICE disc. The inside R pad needs to have the little finger thingy remove so that the pad will clear the spider.

Chris_W

On my single touring bike that has an Avid BB7 disc brake on the front, I also recently changed from an Avid rotor to an XT ICE model. As sine noted, you do need to trim the tab on the inner pad a little so that it clears the rotor arms - it appears that removing the pad will still be possible with a pair a pliers (which are normally needed anyway). I've also been very happy about the power, smoothness, lack of noise, and consistent performance down long descents with the new rotor, so I would recommend it. Aside from the tab on the inner pad, I cannot imagine any compatibility issues, and have not experienced any trouble.

I also have no objective measures of heat build-up but the technology and design that Shimano describes going into these rotors, with the sandwiched layer of alumnimum, etc., is all pretty convincing to me, and I trust that heat management is going to be better than with the more basic Avid rotor.

rdtompki

My daVinci has 8000 miles on it and may be deserving of a new rotor in any event. I think the XT ICE model might be worth a try. The out of round report is a bit concerning since you clearly don't want to be tweaking on the Al spider.

I did go ahead and order the Shimano rotor. I'll get to test it on the 14th since there is one decent (1000') downhill on a Century that day. Won't be the first time I ride with it however.

cobba

An alternate to the Bengal MB700T for those worried about melting pad adjusters might be the Hayes CX-5 which probably doesn't have any plastic parts as it needs a 5mm allen key to adjust the inner pad.

CX-5: https://www.universalcycles.com/shopp...s.php?id=47661

* The Bengal MB700T uses the same pads as the Hayes MX-2, MX-3, MX-4, Sole and CX-5.


What someone said about BB7's & Icetech rotors:

Not saying you can't use them but the Avid G3 & HS rotors aren't really made for use with BB7's either, these rotors have smaller braking tracks which are matched to the pads on Code & Elixir hydraulic brakes. The BB7 pads can overhang the inside edge of the braking track on the G3 and wear the rotor arms. The G2 rotor has a larger braking track that's matched to the size of the pads of the BB7, BB5 and Juicy brakes.

BB7 & Code pads:

BB7 pad wear on a G3:

Ritterview

While on the subject of disc brakes, rotors etc, I've got a question.

Our disc brake (a BB7) often squeals terribly. Lately it hasn't been that bad, as I've sprayed some anti-disc brake squeal spray on the rotor (that I purchased at an auto parts store), and it seems to help somewhat.

On the Death Ride, a mechanic who was working moto sag (and he also works moto camera for Tour of California) noted our squealing (it was really bad that day), and recommended a motorcycle trick, which is use brake pads of differing hardness on either side of the rotor. This, he stated, disrupts the rotor's resonance. That made sense to me.

But I don't know what brake pads he was referring to. If I wanted to try this out, what would be the two brake pads I would use that would both work well, but one relatively soft and the other relatively hard?

rdtompki

Interesting. I'll keep a close eye on on our ICE rotor. Normally, I'd think the total heat load and resulting temperatures would be similar assuming the BB7 pads had a similar composition. It may be that the Shimano rotors themselves combined with their pads, conduct a significant amount of heat. Perhaps someone with a better understanding of typical caliper design can comment? Assuming most of the heat transfer is into the rotor assembly then perhaps the resulting temperatures are similar.

twocicle

Y, I second that. I was also curious about the potential to melt the Aluminum core :O That would lend a whole new meaning to the term "mushy brakes".

It's a chicken vs. egg thing. Which component is more to blame for the heat buildup... the pads or the rotor? My vote is the rotor.

You'd think besides the rotors themselves, the only substantial difference between Shimano vs others would be the brake pad material. Sure the calipers may retain some heat, but it seems the steel Avid's steel rotors would be the most to blame for extreme heat levels seen on the BB7. Then the BB7's default organic pads wear very quickly with heavy usage (ie: you hear of people going through a complete set of pads on just one long, steep downhill like Ventoux), but perhaps that short pad life is due to the very high heat load in the steel rotor?

I have the ICE Tech rotor arriving today, along with the ECB Gold (sintered) pads.

PMK

FWIW, the G2CS, G2 Clean Sweep disc has a similar brake pad overhang. Oddly, I purchased the BB7m with the G2CS discs in one box supplied by Avid. So compatibility is not an issue. The pads absolutely are wider than the disc. You can hear and feel the pad as it passes by the discs spoke.

In comparison, the Co-Motion has early style G2CS 203 discs, the off-road tandems both have later style G2CS disc on the fronts and the Ventana also has this disc on the rear. The Fandango has a 203 Roundagon. They all will stop he bikes, however the new style G2CS on the Ventana are the stronger brakes, next is the old style G2CS, least strong is the Roundagon.

PK

cobba

BB7 pads shouldn't overhang the inside edge on a G2 braking track.
Is there a section on the braking track near the outside edge of the rotor where the pads don't rub ?
If there is then the brakes are slightly out of alignment, a washer or two placed between the caliper and the adapter will move the caliper outwards away from the axle and give proper pad to rotor contact.
Sometimes things don't line up as they should and need a bit of fine tuning.

PMK

Measuring with a dial caliper, capturing the full width of the disc, (Measured from the inside radius edge, to the peak of the outside edge), these are the measurements off our three tandems.

I also want to add that I was in error in the earlier post, The Co-Motion does have early style G2CS discs front and rear, the Ventana full suspension tandem has new style G2CS front and rear, and the Fandango has a Roundagon on the rear and a G3CS on the front, correcting what I previously stated was a G2CS new style. This is what allowed me to obtain dimension from each disc style.

G2CS early style 16.5mm wide,
G2CS newer style 13.94mm wide,
G3CS 14.00mm wide,
Roundagon 15.6mm wide.

I also measured the width of several Avid oem metal brake pads, they dimension at 15.05mm wide.

Knowing the brake pad is wider than the disc surface on a couple of those installations. The amount of pad to the inside of the disc is about 1mm. In preference, it would make more sense to wear the pads flat as opposed to wearing a lip to the outside edge.

Repositioning the caliper would gain the effect of a larger diameter disc, but percentage wise it's very small.

Not sure what else to offer, the dimensions don't lie and I have never seen any tech pubs from Avid that ban the use of a G3CS with BB7m calipers. I even went looking on SRAMs website for it yesterday.

FWIW, the alignment will remain similar, but I plan to remove the ball and cup alignment setup in the near future. We have had occurrences where the calipers have shifted slightly with use over time. Nothing crazy or drastic, just enough to require realignment when rubbing can't be adjusted out easily. When I do the rigid non-adjusting style mounts, I'll postion the pads outermost edge tangent to the disc.

PK

cobba

I guess measurements don't lie. The only differences I've noticed in the G2 over the years is that older ones had 6 notches on the outer edge of the braking track and the newer ones have 12 notches, I didn't know they changed the actual size of the braking track.

There's nothing I've seen either to say you cant use them and I'm not saying you can't, I'm just saying that going by the measurements of the 'old' G2, the measurements of the G3 and seeing the size of the pads in the brakes that were sold with these rotors, that doesn't it look like the 'old' G2 rotor was designed more for use with the BB7, BB5 & Juicy brakes which have pads sized to match the size of its braking track and the G3 which has a smaller size braking track was designed more for use Code & Elixir brakes which have pads sized to match it.

As the 'newer' style G2 has a slightly smaller braking track then a G3, I guess there wouldn't be much difference in the two and what I've already written doesn't really matter much.

I wonder why Avid changed the specs of the G2 rotor ?

Werkin

I can verify a narrower swept area on the last G2 rotor purchase. It hasn't negatively affected performance on my single bike, in fact the rotor was true out of the box, hasn't warped yet, and no judder, can't say the same for the early G2. Pad wear is uniform also.

Be aware ICE non-floating rotors with aluminum carriers were designed for self-centering hydraulic systems. BB7s require a flexible rotor/spider/carrier, or floating pins, for optimum performance and even pad wear.

rdtompki

That's an excellent point and I'll be sure to inspect the ICE rotor very frequently. My initial observation on a 1000' downhill is that the ICE rotor with KoolStop metallic pads required much less pressure to develop braking action. There were no switchbacks and with the roads a bit damp I kept my speed down, but the lever pressure is definitely less than with the Avid rotors.

gracehowler

Avid makes a "standard" metallic pad and an organic pad for the BB7. After working on foreign cars for 25 years, I learned organic pads are quieter, actually many oem brakes are organic. I see no reason one couldn't mix one of each, but the organics don't last as long and brake inspections would be more important. Our next pad change will be organic, we are tired of the noise also.
R&J

twocicle

Installed the Shimano XT RT86 IceTech 203mm today and still using the default Avid "organic" pads for now. Snipped off the inner pad's pinch tange to clear the AL spider arms as previously mentioned in this thread.

Then performed a few high speed wheel rotations and manually applied the brake caliper. You'll see the pad engagement track marks on the rotor.

Interestingly, with the Avid steel rotor we had zero chainstay clearance on our 2007 Calfee. The IS mount bracket, Avid caliper and Spinergy wheel hub all lined up on the frame, but the tolerance to the chainstay is minuscule with a 203mm rotor. Our local bike shop here had an interesting suggestion - maybe try a 200mm rotor instead, but you know the available selection of 200mm rotors is not great.

Now with the Shimano rotor there is maybe .5-1mm clearance. The back side of the Shimano spider appears to have a slight concave offset which may be what is providing that slight increase in clearance for us. The resulting rotor alignment in the Avid caliper is still spot on too, after the obligatory CPS readjustments with the new rotor.

Oh, one last tidbit... I weighed the Shimano rotor, fixing washer and tightening plates at 175gm (vs the Avid rotor G2/G3 at 230gm).
https://bike.shimano.com/publish/cont..._mountain.html

Chris_W

The 160mm XT ICE rotor that I'm using with a BB7 on my single bike has exactly the same wear pattern shown in twocicle's image of the 203mm rotor. The depth of the brake track on the ICE is 15.0 mm, and I think the pad contact height is pretty much ideal looking at the wear.

The comment about the alu spider being stiffer, and so is not suited for use with a non-centering cable disk brake is interesting. It makes sense, but I'm not sure what sort of issues one should expect if this guidance is violated. When Shimano announced their new cable disc brakes recently, I don't recall seeing anything about what rotors they recommend to use with them. They are not yet available for sale, and there is no info on Shimano's website yet, but I will be interested to see what they recommend.

twocicle

Forgot to mention, the Shimano RT86 rotor was perfectly true to the eye. I hope to get the Calfee on the road today or tomorrow for its maiden voyage.