Tandem Cycling - Another disc brake on a Calfee thread.

So I installed the Avid BB7 with EBC gold pads and Hope floating rotor (oh.. and the Power Brake Booster).

Here's the basics:

- I had to grind a little bit of material off of the caliper with my trusty die grinder to clear the rivets of the rotor (connecting the middle section to the outer section of the rotor. It wasn't a big deal, just a bit where the caliper pokes out near the rear caliper mounting bolt.

- Wow the tolerances are tight on pretty much everything, but nothing rubs.

- Man this stuff adds a lot of weight!!

Notes/Thoughts:

It took me a while to get it setup, but finally ended up with a decent lever feel, firm, etc.. However, it just doesn't stop well yet. Not very grabby, at all, and need a good deal of hand effort to get good power.

Now I know they need to break in, and I hope they do so soon.

I finished the bike on Friday, last week, and we were able to only get a quick 7 mile ride up and down some neighborhood hills, to test everything out, and help bed the brakes.

Then on Saturday we did the Mt. Tam Double Century, which amounted for 200 miles and 16,700 feet of climbing. Most of which was steep up and down rollers... ugh.. not good terrain for testing :rolleyes: I think I must have shifted over 2000 times, seriously!

The bike did pretty well, I have to fix a couple things that bugged me, but the ride of the frame was nice!

Thing that's bugging me, is the disc brake, it still doesn't have very much stopping power. Should it take more than 200 miles to break that thing in???

Thing that's bugging me, is the disc brake, it still doesn't have very much stopping power. Should it take more than 200 miles to break that thing in???

Unfortunately, I have no first hand experience with your Hope rotor and EBC brake pad set-up

I can only speak to the break-in period for Avid's 203mm G2 Clean-Sweep rotor and their OEM pads which, at least based on breaking-in two different tandems with the same set-up, seemed to have two distinct break-in periods:

1. Initial stopping power out of the box was non-existent but by over-using the rear brake during a short 30 mile / 2,300' ride from home the OEM pads bedded-in and seasoned the rotor to the point where I could drag the tandem to a near stop from 25 mph to about 4 mph on an 8% grade under full-braking at which point the rear tire finally locked-up the rear wheel and skidded the rear tire. From my journal....



As for performance, on our first day back on the Calfee with the Avid rear disc I intentionally over-used the rear brake to accelerate the bedding-in process over our 30 mile / 2,300' regular loop ride from the house. By the time we were headed down the 8% grade into our community I was able to get the rear wheel to lock using only the rear brake. The following weekend we did an in-town ride with three other couples. For those who don't know, the city of Atlanta and its surrounding communities north of I20 are actually quite hilly in many areas. Anyway, as I did yesterday, I intentionally overused the rear disc brake and by about 1/2 way through the ride the stopping power was well on its way towards what I would call "normal" for an Avid BB7 with 203mm rotor. It had been over a year since we'd ridden our Avid BB7 equipped '02 Erickson and it was nice to have a really grippy rear brake back on the tandem. While we really don't need it for most of the rides we do locally, it's wonderful to have when we head up to the regional mountains.

2. Once the brake pads have completed that initial bed-in process and the rotor is seasoned, our rear disc brakes have exhibited a further and somewhat progressive increase in braking power over a few hundred miles until somewhere around 300 miles or so there was a pronounced increase in brake bite. However, it's noteworthy that during this break-in period the Avid's caliper required a routine post-ride brake pad adjustment to compensate for the very quick, initial wear that occurs as the OEM pads wear down the higher contact surfaces (upper edge of inner pad, lower-edge of outer pad) and end up with an off-camber wear pattern that is essentially faced to match the rotor's position under full brake power: remember, the rotor is pushed ever so slightly inward against the inner, fixed brake pad by the actuating arm, hence the off-camber wear.


So, getting back to the Hope & EBC pads, it could be that you've created a longer break-in period by going to the longer-wearing / sintered EBC Gold compound and perhaps the Hope rotor's lower-heating characteristics or differences in the stainless steel used for the rotors are further exacerbating the length of time it will take for the pads and rotor to bed-in. Again, it's been somewhat interesting to me that my break-in periods were not really that linear. There was some initial improvement that occured at a somewhat steady rate of progress as the brakes were used followed by an incremental 'jump' that took me by surprise when the brakes really started to bite. Again, I've also not had to use any type of an in-line brake booster (PBP or Travel Agent) on either of our Avid-equipped tandems so once again I can't comment on how they may or may not alter the break-in process and timelines.

One more note I should add:

Despite the Hope rotor being spec'd at 203mm, I needed to run one thin washer on each caliper mounting bolt to space the cailper outward just a tad.

I recently tried Swiss Stop pads with the Avid rotors, not happy with it at all, lever feels mushy, braking feels nonexistant. Pads have had a reasonable time to season, 300 + miles at on hills in the Santa Cruz mtns. I will switch back to the Avid organics. I have been working on parts for the Hope floating/vented disc,I should have some results soon.

another question...

How true are your rotors?

This one seems slightly out of true...

How true are your rotors?

Very true, +/- .5mm

And, I'll make a confession to another stupid human trick that I've used: I throw new rotors in the oven and anneal them at 500* for about 10 minutes and let them cool before mounting. I'm not sure how much it reduces the hardness (I'm guessing not much), but it seems to make the rotors mount-up and run true and it also gives them an interesting bronze-gold tint.

I'm not recommending this to anyone because, as I said, I'm not smart enough to know if there is any downside to the process or if what I think happens really does. Given how hot rotors get in use, I simply assumed it was a safe bet that there was no down side.

Now, as to why I even thought to stick a rotor in the oven... The rotor on our '02 Erickson was a wobbly mess and I got fed up trying to true the thing. So, after pulling it off and staring at it sitting there on the work bench I had a flash of brilliance: I wondered if the stainless steel alloys used in rotors didn't have a little bit of 'memory' such that any cold-set bends created during shipping, storage or handling might not go-away once heat was applied to the rotor. So, into the oven it went.

Anyway, so far so good. I haven't cracked any rotors or observed any other ill-effects and it did seem to make the rotor spot-on for trueness after the oven treatment.

Sounds like this was the maiden voyage of the new bike. Congratulations.

Might you do a write-up comparing old bike to new bike?

another question...

How true are your rotors?

This one seems slightly out of true...

Are you saying the new hope rotor is out of true or are you refering to the original Avid rotor? My vented Hope is still stting at the shop, I have not checked it for trueness.

Also when attaching a rotor it should be tightened in a star pattern similar to what you do when mounting a car wheel.

Dropped off the modified Avid S/S clips at the machine shop today. Hopefully my vented disc will soon see some use other than a coffee coater.

Has anybody actually blown a tube using rim brakes?
In 20 years of tandeming I never have.
When I read about all the issues with disk brakes plus the extra weight and cost I don't think I want to go there. I could see how they would be nice to have in the rain but I don't ride in the rain normally.

Didn't I see a thread discussing improved performance of even the non-vented Hope rotor over the standard Avid rotor? My wife and I are satisfied with braking performance so far (rear avid disk) and we're not racers, but you can never have too much braking for a given weight penalty.

Has anybody actually blown a tube using rim brakes?

In Question #8 of a survey I conducted last winter, 17 of 291 respondents (6%) indicated they had suffered a tire blow-off due to rim heating. Another 19 (7%) indicated they had experienced total brake fade / loss of stopping power.

Looked at another way, and given that 212 of the survey respondents did not report any serious tandem component failures, 45% of the 79 folks who reported serious problems cited brake-related issues.

You can find the survey results here: http://www.thetandemlink.com/surveys/fallsurvey_08a.htm

My Survey Archives can be found here: http://www.thetandemlink.com/surveys/surveycentral.html

Are you saying the new hope rotor is out of true or are you refering to the original Avid rotor?

The Hope.

I never bought the Avid rotor.

Has anybody actually blown a tube using rim brakes?
In 20 years of tandeming I never have.
When I read about all the issues with disk brakes plus the extra weight and cost I don't think I want to go there. I could see how they would be nice to have in the rain but I don't ride in the rain normally.

Depends where/how you ride in determining whether or not the disc is worth it.


I am willing to do a little test & tune to figure it out and see what kind of results I get.

If in the end, I don't see a worthwhile increase in performance/confidence. I have a rear caliper ready to go on. But, from what I know and have read, the disc has potential to be quite nice for the terrain/type of riding we do. So, because of that I am willing to put up with some initial growing pains.

In Question #8 of a survey I conducted last winter, 17 of 291 respondents (6%) indicated they had suffered a tire blow-off due to rim heating. [/url]

What is meant by a tire blow off? Is it the inner tube blowing due to heat and then the tire coming off rim due to on air in the tube? Or is it the heat directly affecting the tire?

What is meant by a tire blow off? Is it the inner tube blowing due to heat and then the tire coming off rim due to on air in the tube? Or is it the heat directly affecting the tire?

I don't believe a conclusive test or analysis of incidents has been conducted to come up with a definitive answer to that mystery.

My personal unproven theory is that wire-beaded tires seem to be involved in most all of these incidents and acts as a heat sink that when conditions are just right (e.g., very high brake heat, thin-wall or well-worn or aged inner tube mated with an older tire) the inner tube will be weaked along the bead and eventually fails in a dramatic way and with enough force that it unseats the bead and/or blows-out the tire sidewall.

It also occurs to me that it's the cautious descenders who will usually experience the blow-offs, not the folks who bomb the descents and reap the benefits of rim cooling vis-a-via air flowing over the rims at a fairly high velocity in between moderate check-speed braking and short, but very aggressive braking at the entrance to corners. Conversely, the cautious riders will apply constant braking throughout the descent at low to moderate speeds that don't help to bleed-off heat from the rims, thereby allowing rim heat (and, in turn, wire bead heat) to build up to higher temperatures for longer periods of time.

In fact, one of the more interesting things I've seen on at least two occasions that I can remember are teams who made controlled descents without suffering a blow-off during the descent but who immediately came to very aggressive dead stop at the bottom of the hill and within moments thereafter "BOOM"; the rear tire blew. Again, I theorize that it's the cummulative heating and lack of air flow that will allow a wire rim bead to weaken an inner tube to the point where it bursts and, clearly, if you come to a dead stop after using maximum braking at the bottom of a long descent, your rims and the wire beads will be about as hot as they'll get at any point in time.

Thanks for the detailed explanation. Of course its something we all want to avoid.
I do try to avoid braking when possible on long hills.
I have been using wire bead tires (Gatorskins) for many years because I had an experience with a folding tire that blew off the rim due to pressure several times. I believe it was due to the tire / rim combination. I didn't realize the wire bead could be involved in transfering heat to the tube. Right now I am trying a Rubino Pro folding tire on the back and have only ridden it once so far.

Has anybody actually blown a tube using rim brakes?

I've never had one blow off on my tandem but I did on my single bike back a few years back. I think it really depends on the type of riding you are doing. I was on a long, steep (6-15%) curvy descent. It was fast too, 50+mph. Luckily I felt the tire go out of round (ie thump,thump, thump), got the bike stopped and got off just in time to watch it go BOOM! The tub actually pushed the nearly new tire (Conti GP3000?) right off the rim before it exploded.

I agree with jnbrown that variation in wheel diameter/tire diameter can be a significant contributor to the problem. Some tires go on some wheels very easy and not on others. On that bike it was always very easy to put the tires on by hand. I personally feel that contributed to my case.

Since I've had that happen on my single bike, I take no chances on the tandem. I do a lot of fast technical descents and that is something I don't want to have to worry about.

I popped a tire on a Downtube Mini, 16" wheeled, folding bike going down Alpe d'Huez :)

Damn little wheels!!

Of course it was coming down the mountain after the TdF stage, so there was LOTS of braking.. that plus small wheels = BOOM!

See tube! (:eek:)

http://farm4.static.flickr.com/3068/2732910169_cbc2de41d5.jpg

http://farm4.static.flickr.com/3207/2717026554_c4e8cf348a.jpg

Is the rotor hub showing runout side to side, or the disc. Being a floating design, it may not be exact but should remain more true under heat of braking.

PK

I didn't realize the wire bead could be involved in transfering heat to the tube.

Like I said, it's a theory of mine driven mostly by the disproportionate number of wire-bead vs. folding kevlar beaded blow-offs on tandems... and the higher heat loads.

I do agree with the other problems associated with mis-matched tire & rim combos. I recall that back in the late 90's there was a raft of problems with Specialized tires, the Armadillos at first and then the Turbo/A's and there have been a few other rim and tire combos that just didn't work well.

+1 on TG and Chichi's comments. I am also using the Hope rotor with the standard Avid pads and notice a significant difference in both stopping power and the rotor remaining true, even after really heating it up. I also run very tight tolerances. We descended some long, steep grades in CO this summer that required me to be on the brakes a lot due to slow traffic. When I finally stopped, the Hope rotor was so hot that it was "ticking" from the sound of the rotor and spider cooling down. No rotor warp. You might want to go back to the standard Avid pads and give them a try.
To improve the brake response, I replaced the typical 5mm spiral wind brake cable housing with BMX linear wire brake housing. The spiral wind produces a lot of cable housing distortion when squeezing hard on the brake lever. The linear wire brake cable housing literally stops the distortion. I am able to contact the rotor with very little level movement and feel the bike slowing with very little additional pressure.

To improve the brake response, I replaced the typical 5mm spiral wind brake cable housing with BMX linear wire brake housing. The spiral wind produces a lot of cable housing distortion when squeezing hard on the brake lever. The linear wire brake cable housing literally stops the distortion. I am able to contact the rotor with very little level movement and feel the bike slowing with very little additional pressure.

Even the run of housing to the handlebar? Does it flex enough?

Change the handlebar housing also. The rear housing on the handlebar is as long, or longer, than the rear housing. I even changed my front brake cable housing. You won't notice as much difference since the length is so short. Forgot to comment on your BPB. There is an upper and lower hole to insert your brake cable housing. Since you are using (I presume) road levers, make sure you insert the cable housing into the lower hole. You will have greater travel distance of the cable when you squeeze the brake lever. Thus, you are able to apply more pad pressure to the rotor.
Forgot an additional comment on our descent in CO. Yes, the rotor got hot enough that I could hear the ticking sound while the rotor cooled off, but I also got no fade on the brake. Maybe another reason to go back to the original Avid pads.

Change the handlebar housing also. The rear housing on the handlebar is as long, or longer, than the rear housing. I even changed my front brake cable housing. You won't notice as much difference since the length is so short. Forgot to comment on your BPB. There is an upper and lower hole to insert your brake cable housing. Since you are using (I presume) road levers, make sure you insert the cable housing into the lower hole. You will have greater travel distance of the cable when you squeeze the brake lever. Thus, you are able to apply more pad pressure to the rotor.
Forgot an additional comment on our descent in CO. Yes, the rotor got hot enough that I could hear the ticking sound while the rotor cooled off, but I also got no fade on the brake. Maybe another reason to go back to the original Avid pads.

- Yep, I am using the lower hole on the BPB.
- I heard the pinging after a long descent (while stopped at a rest stop) last weekend. Pretty cool actually (function of the floating rotor)
- Compressionless housing seems like a good idea. I can see the spiral housing flex A LOT, when I squeeze the lever.
- I will give the EBC pads a couple more rides, then swap in the Avid pads, if they aren't working out.

Thanks,
Marco

This does sound like a compatability problem. 203 mm discs will stop you quick enough with the extra leverage with the large disc. But somehow stopping power is not there. Don't know the pads you are using but try another make/grade to see if it makes a difference. But to me it sounds like the Brake lever is incompatable with the caliper. Somehow you are not getting enough leverage on the brake pads. perhaps the leverage is is wrong or the brake booster not working right.

And on preheating the discs. It has been noted on a few Dusk rides- that after heavy braking my Discs are giving out a dull orange glow. Didn't believe it till I put a gloved hand on it and the gloves started smoking.

Well. I was going to post that... well the brakes were feeling more grabby, and that maybe they were finally broken in... I was feeling pretty good about them, until Saturday.

We had just climbed this ( http://graphics.stanford.edu/~lucasp/grade/bohlmanonorbit.html ) and had to descend it.

We have done this before, on the old bike, by the way.

Well the rear brake just wasn't giving me enough power. The lever felt OK. It's wasn't really fade, becasue it felt underpowered from the get go.

It was about 85 degrees out, which doesn't help. Anyway, I ended up having to use too much front brake in order to slow down enough, and blew out the front tire *POP!!!!*. The tube actually blew apart, the tire came off the rim. Luckily I was able to point it straight, and keep it upright.

Unfortunately the road, is not an uber-smooth glass like roadway, and the "chunkiness" of the roadway bit into the rims quite a bit, as well as piercing the sidewall of the tire.

We got a new tire at the LBS and tried to finish our ride, but got a couple flats, due to the burrs on the rim piercing the tube. So we had to get picked up by a friend of ours.

Here is the tube, it wrapped around the fork/hub. It also completely blew apart. The valve stem was also blown off... In fact it looks like the heat transfer went to the valve stem, which looked to be the origin of the blow out.

http://lh3.ggpht.com/_pxY28OCdAfg/Sn41u2pVfVI/AAAAAAAACfw/RJI0YEVQxKM/s640/IMG_0903.JPG

http://lh4.ggpht.com/_pxY28OCdAfg/Sn41wF2RJgI/AAAAAAAACf0/Bv6YDiFUDFw/s640/IMG_0904.JPG

I got some of the compressionless housing . Have to get a new cable today. I installed the Avid pads as well. We shall see how it goes.

I will get the rim looked at to see what can be done. Otherwise I will order a new rim, and rebuild the wheel.

USPSPRO: Well at least you kept it upright. That hill climb looks pretty sick. Have you thought about going back to calipers front and back and putting the disk in the toolbox?

That hill climb looks pretty sick.

Yes it is.. 9% avg makes it sound easier than it really is, since there are a couple of breaks on the way up. There are considerable extended sections above 15%.

On the web page I linked, scroll down to the "Raw data" text, and it will really give you an idea of what that hill is like. :twitchy:

USPSPRO: Well at least you kept it upright. That hill climb looks pretty sick. Have you thought about going back to calipers front and back and putting the disk in the toolbox?

Looks like the wrong conclusion to me. USPSPRO's experience only shows to which extend rim brakes are working close to/beyond their heat limits when going downhill (with a tandem). We have the stock Avid BB7 brakes/discs and have been very pleased with them (we live in Geneva, Switzerland so we don't ride on flats:thumb:). I have replaced the avid pads on the rear with koolstop as they had worn out. Seems to me that the koolstops are smoother (just like their rim pads tend to be).

What I don't understand is, is why people want to use different discs as they seem to give fit problems and kill brake performance.
USPSPRO : from your pictures and stories on BF, I know that you guys are well trained (light team) and know how to handle the bike (no need for excessive braking on descends). I really don't think you should worry too much about fading with the original Avid 203mmm discs. At least, we never had a problem with ours.

But the main point is, whatever you try, keep it safe.

USPSPRO.....Yikes!! ...you dodged another bullet.... 'love your gusto and take no prisoner style, but dude... you are burning through your nine lives waaaaay too fast :) . Enjoy the ride.. but save some of them for your autumn...I promise you will need 'em then as well!

Bill J

Looks like the wrong conclusion to me. USPSPRO's experience only shows to which extend rim brakes are working close to/beyond their heat limits when going downhill (with a tandem). We have the stock Avid BB7 brakes/discs and have been very pleased with them (we live in Geneva, Switzerland so we don't ride on flats:thumb:). I have replaced the avid pads on the rear with koolstop as they had worn out. Seems to me that the koolstops are smoother (just like their rim pads tend to be).

What I don't understand is, is why people want to use different discs as they seem to give fit problems and kill brake performance.
USPSPRO : from your pictures and stories on BF, I know that you guys are well trained (light team) and know how to handle the bike (no need for excessive braking on descends). I really don't think you should worry too much about fading with the original Avid 203mmm discs. At least, we never had a problem with ours.

But the main point is, whatever you try, keep it safe.

USPSPRO said earlier that he has ridden this same descent on previous bike (rim brake only). If the rim brake only performance was good enough before, why wouldn't it be OK now? The rear disk (and new frame) was the big difference between the previous experience and this occurance. Maybe tire differences and ambient air/asphalt temp differences could have also played a role....Has NTSB been called about this?

USPSPRO.....Yikes!! ...you dodged another bullet.... 'love your gusto and take no prisoner style, but dude... you are burning through your nine lives waaaaay too fast :) . Enjoy the ride.. but save some of them for your autumn...I promise you will need 'em then as well!

Bill J


Haha... it wasn't really all that crazy. I mean I brought the tandem to a controlled stop, at the expense of a Velocity Deep V rim :crash: sigh...

<uspspro wrote: "It was about 85 degrees out, which doesn't help. Anyway, I ended up having to use too much front brake in order to slow down enough, and blew out the front tire *POP!!!!*. The tube actually blew apart, the tire came off the rim. Luckily I was able to point it straight, and keep it upright.">

Wow - you're obviously a very skilled rider/team to maintain control under conditions like that!

I'd like to offer an alternate sequence of events: that the tire sidewall failed first (due to the excessive heat build up from hard braking, high ambient temps, slow descent speed, and/or a defective tire) and THEN the unconstrained inner tube exploded.

This type of tire failure actually happened on the front tire of our tandem - in our garage - hours AFTER riding a century with about 4500' of climbing/descending. The tire in question was a 28C Gatorskin with less than 600 miles on it, and it was pumped to 115 psi that day (team weight is 275#). There was no evidence of sidewall damage - the sidewall material tore at the bead, under the lip of the rim (see picture below). The tire had only been mounted ONCE.

I contacted Continental North America and sent in pictures, but was offered no real explanation as to how/why this could occur. The rim in question was a Mavic T217 and the tire/rim fit was tight, but totally mountable by hand without tools. I suspect that heat from the rim and a defective sidewall material/manufacturing process may have contributed to the failure.

We continue to ride 28C Conti Gatorskins but I closely inspect the bead/sidewall whenever possible prior to major descents ...

About your disc brake setup - i mounted a 220mm downhill floating Formula rotor with Avid BB7 on the rear of our Santana, and have found EBC gold pads far superior to the original Avid pads in terms of wear and fade resistance. The real test was descending Independence Pass into Aspen (nearly 4000') during Ride the Rockies this summer - narrow and steep with unusual traffic due to sags and slow singles :) Braking was exceptional, with no fade.

Estimate that we use the rear disc now for 80% of braking in mountain descents without fear of rim heat build up or fade. It sounds like your pads may be contaminated if they haven't broken in yet - we had braking that was clearly superior to Avid V-brakes within 100 miles.

Again, nice job on saving the day and good luck with getting your new Calfee dialed in!

Wow, I have been planning to get my Calfee with the same combination of Avid BB7 and a front caliper, only I was thinking of using a carbon clincher, which doesn't dissipate heat as well as aluminum, and likely would have melted prior to the tire blowing.

Then I saw you were doing the legendary Bohlman-on-Orbit, which has I think the 3rd steepest 2 mile climb/descent in the U.S., according to The Complete Guide to Climbing (By Bike) (http://usacyclingclimbing.com/). So, if you looked all over the U.S., you'd have trouble finding a descent more likely to result in rim overheating.

For your next trick, head on down to Hicks/Umunhum (http://trail.motionbased.com/trail/activity/6954117) all the way to the top. Its 9.8% grade makes it for 4 or 5th, steepest 5 mile climb/descent in America. That'll put your Avids to the test.

For your next trick, head on down to Hicks/Umunhum (http://trail.motionbased.com/trail/activity/6954117) all the way to the top. Its 9.8% grade makes it for 4 or 5th, steepest 5 mile climb/descent in America. That'll put your Avids to the test.

That was our destination after Bohlman actually :lol:

My thoughts for what they are worth (about what you are paying for them)

Have an experienced mechanic set up your brakes, there are plenty in the bay area.

Ask the mechanic to review the adjusting procedures with you. Tandem disc in a hilly area is a severe application and will require maintence, I go thru a set of pads about every 1000 miles .
Don't ride down hills like Bohlman instead ride all the way over and come down Montevina still steep but more manageable then Bohlman. There are times when you may find you have no way out but going down something like Bohlman but it is crazy to put you and more importantly your stoker in that spot if you do not have to. I have done Bohlman a few times on a single and I just don't find the downhill risk worth the uphill.

Put a reinforcing gasket made of an old inner tube at the valve stem, LBS has been doing this for past 4-5 years says he sees lots of tube failures at the stem, this seems to help.

I think you dodged a bullit on this one, be careful out there.

Don't ride down hills like Bohlman instead ride all the way over and come down Montevina still steep but more manageable then Bohlman. There are times when you may find you have no way out but going down something like Bohlman but it is crazy to put you and more importantly your stoker in that spot if you do not have to. I have done Bohlman a few times on a single and I just don't find the downhill risk worth the uphill.

We have gone down Bohlman on the old bike without issue. I don't see how, with a properly performing disc brake, this shouldn't be an acceptable thing to do.

Don't people ride tandems down Brasstown, and all those other crazy steep hills.

PS- Thanks for the tip about the reinforcement tube... did you get that from George (Slough's). :)

So... an update on this.

- I switched the pads from the EBC gold pads back to the Avid stock pads
- I switched to compressionless brake cable housing

Hoping the results are better.

If you remeber I was recently complaining about the performance of swisstop pads in the Avid calipers.

I had the Lbs review set up for me:
1. create slack in the brake cable
2. Adjust barke pads to be a s close as possible to rortor with out rubbing
3. Take the slack out of the brake cable (using barrel adjuster)

Those swisstop pads are now working just fine. I think I had a lot of slack in the brake cable and was wasting lever movement removing cable slack instead of moving the brake pads. I am using TG's helper sping which insures that the pads move away from the disc every time you release the brake lever.

"Put a reinforcing gasket made of an old inner tube at the valve stem, LBS has been doing this for past 4-5 years says he sees lots of tube failures at the stem, this seems to help"

Interesting idea. Might this be just taking a 1" x 1" (or so) piece of old tube, punching a 3/16" (or so) hole in it and placing over the valve stem prior to inserting into the rim? I could see how this might act as a strain reliever for the stem/tube interface.

"Put a reinforcing gasket made of an old inner tube at the valve stem, LBS has been doing this for past 4-5 years says he sees lots of tube failures at the stem, this seems to help"

Interesting idea. Might this be just taking a 1" x 1" (or so) piece of old tube, punching a 3/16" (or so) hole in it and placing over the valve stem prior to inserting into the rim? I could see how this might act as a strain reliever for the stem/tube interface.

You are correct

Just a quick update here:

Cables

- I bought some Yokozuna "Reaction" cable housing, after reading numerous rave reviews about the stuff. I had to buy a whole set of shift/brake housing and cables, but I am just using the brake housing (on the rear brake) for now. The housing is compressionless, using co-axial wires (like shift housing), but then wrapped with spirals (like brake housing), and has a cool clear sheath to show off its black/silver construction. It also is "jet-lubed" inside the housing. The reviews say this stuff is super stiff, and very very low friction.

Brake Power Booster

- I eliminated the Brake Power Booster (aka BPB). My theory is that: Sure you get a longer pull on the caliper end for a given pull on the lever end, but that you lose a great deal of mechanical advantage. For example, imagine having to tighten an already tight bolt an additional 90 degrees. If you did it with a short stubby wrench, the amount of movement you hand would move to achieve the 90 degrees is smaller than if you used a long breaker bar. However, you have to really put some effort in with the short wrench, while it turns easily with the breaker bar.

----- So BPB setup = more caliper pull per lever pull, firmer lever due to LESS leverage, oh and.... ugly :p
----- Non-BPB setup = less caliper pull per lever pull, softer lever because of the leverage you have, and much prettier :love:

Pads

- After thoroughly reading every review I could about the brake pads I have here (EBC Gold and Avids), I decided to give the EBC another shot, since they are supposed to be much more fade resistant, and longer lasting than the stock Avid pads.

- I thought that, perhaps, we hit a little too steep/long of descents early in the break-in process (during our double century on 8/1) and the pads might have glazed over a bit. I know that in the world of automotive disc brakes, improper break-in can lead to this result. I have done MANY automotive brake jobs, including race setups (autoX - SCCA CSP and SM2). With that said, I decided to lightly sand the friction surfaces of the EBC pads, and to clean all the braking surfaces (rotor and pads) with alcohol.

Results

- Wow, It took A LOT of adjusting to get it just right, but it works great. I am able to lock the rear tire with both the stoker and I riding at around 15 mph on flat ground! :D ... and without a He-Man grip... nice lever feel.

- No fade, even being heavily used on a twisty decent off Mt. Tam. Including a full stop at the ranger station to get water on the way down.

- Plenty of power, more than the front, for sure.

- Looks SO MUCH better, and feels much better (more importantly) without the BPB

- The cables live up to the hype. Very low friction, feels super light prior to pad/rotor contact. Yet feels pretty firm once you hit it. I felt the levers of some stock Co-Motion tandems, equipped with the BB7 at Bicycle Outfitter (LBS known for tandems), and mine felt much better than all of them. 3 out of 4 bikes, the lever could touch the bar almost immediately after pad/rotor contact. The fourth was acceptable, but could be better. I know they could probably use adjustment, but still, I have to say my lever feel is great. So definitely a good purchase in my book!

Issues

- Won't stay perfectly adjusted. After a while, I get rub and have to re-adjust... I think either the caliper is moving slightly, or the rotor is changing shape. Perhaps those additional thin washers that I have added to the calipers (under the positioning washers, as to not interfere with those), to fit the Hope rotor, are allowing caliper movement? Or, maybe the Hope rotor is just out of whack. Either way, I am going to go ahead and order a new Avid Clean Sweep G3 203mm rotor, remove the washers, and give that a try. I have a feeling that it will work fine after that. I could have received a dud Hope Rotor, but rather than gamble on getting another one, I will just get the Avid.