# Formula 220mm rotor for Tandem?



## Speedub.Nate (Dec 31, 2003)

I took delivery of my 203mm Avid mechs, still waiting on the disc wheelset to arrive.

Yuck, they shipped the Avids with 6-spoke "Roundagon" rotors.










Had they come with the 203mm Clean Sweep rotors, with twice the number of
spokes plus the secondary inner flange, I'd wouldn't have found myself in this position.

As far as I'm concerned, more spokes = better heat dissipation, and by most user 
accounts, the Clean Sweep design is quieter and smoother at the lever.










So I started poking around the web, looking at rotor options. I stumbled up this:

Formula Oro *220mm* rotors with adapters. That's 8.8" of stopping goodness, which 
could be nice for a heavy tandem team. Hmmmm...

(Note that they have only 6 rotor spokes, like the Roundagons.)










That's when I emailed Formula, and got the following response:



Formula USA said:


> Hi Nate,
> 
> - We do not recommend any of our products for tandem use.
> - brake track varies, but it should be used with pads which are
> ...


At 236g, that's 20% more material to store and carry away heat than my stock 
196g Avid Roundagons, _*plus*_ 8% extra braking power!

But what about the heat shedding properties of the version with the 2-piece 
alloy carrier?










Wouldn't an all steel rotor have more material to conduct heat away from the braking 
track?

So I studied up on the internet, and it seems that two-piece rotors can resist 
warping better, but I don't find a clear answer as to which type runs cooler. Some 
internet experts say the 2-part rotors store MORE heat in the braking track!

Another email to Formula, and they write back:



Formula USA said:


> Hey Nate,
> 
> Heat dissipation wise&#8230;they are fairly similar&#8230;you wont see a difference
> between one or the other. It is primarily a weight and looks thing&#8230;.


A "looks thing." Hmmmm... interesting. Definitely a (honest) response I did not 
anticipate, as some other brake companies are quick to tout their carrier-mounted 
rotors as "more better" in the cooling department, without further explanation.

Alternatively there is Magura's "Ventidisc" which claims to reduce heating by 15% 
through the use of fan-like blades build in to their aluminum carrier (though their 
largest is a 203mm diameter).










There's also Hope's intriguing vented V2 3-piece laminate rotors, which also claim 
15% temperature reduction. Though at 3mm thick, these would mate up with my 
Avids only with worn pads installed.










So back we are to these sweet looking, not approved for tandem use, no better 
cooled than a common all-steel rotor, Formula 220mm plates.










To make matters worse, they don't match the blue and yellow Cannondale one bit. 










So what advice does the peanut gallery have to contribute?

I'm up for some experimentation. Common sense would say to install the stock Avid rotors first, and see how they work... but then I can't sell 'em "as new" on eBay to recoup some of my investment.


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## Speedub.Nate (Dec 31, 2003)

The BB7 outfitted with 203mm rotors, by the way, is approved by Avid / SRAM for use on a Tandem, according to numerous sources on the web, and is sold by many tandem shops either as aftermarket equipment or as a braking option on complete tandem builds.


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## Speedub.Nate (Dec 31, 2003)

I should say "Welcome!" to the visiting Double Forte forum members. (I notice a number of visiting "guests")


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## cmckim (Jul 18, 2007)

Speedub.Nate said:


> Common sense would say to install the stock Avid rotors first, and see how they work... but then I can't sell 'em "as new" on eBay to recoup some of my investment.


Try them out. If they work, you are done. If you decide to sell them you're only out 20-30 bucks selling them as "used".

Do you have your fork yet?


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## Speedub.Nate (Dec 31, 2003)

Nope, no fork yet. Alex ordered it from ATC a week ago. I'm assuming, once built, it has to ship from SoCal to Georgia then back to the the San Francisco area. 

So for now we're making do with the stock fork and the Magura rim brakes.

I think the Avid rotors, new, are only worth $30 or $40.


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## sparrow (Dec 30, 2003)

We've been running a 190mm front, 160mm rear Magura Gustav on our El Conquistador de Montanas and get plenty fine braking. 350lb team, riding rugged singletrack and some racing, too. So there is certainly more to consider than *just* rotor size, cooling, venting all that jazz. Front braking is where the power is, and tandems have front braking leverage like no other bike. And a high quality DH level hydro disc brake system is hard to beat. The Avid mechanicals are not slouches and I'd bet the 203 rotor on the bb7 will be fine for some serious offroading. Enjoy that bike, the fork and brakes are going to spoil you. 

Speedhub.Nate, have you started saving up for a Rohloff equipped Ventana ECdM yet? You know that's where all this is heading......


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## Speedub.Nate (Dec 31, 2003)

sparrow said:


> Speedhub.Nate, have you started saving up for a Rohloff equipped Ventana ECdM yet? You know that's where all this is heading......


Partly... er, in my mind, or something like that. It'll more than likely be a 29"er, and it'll more than likely be quite a few years from now, so there will more than likely be more to choose from than the current Jeepster offerings. We'll see.

To late, ya'all, I just placed the order for the rotors. Total unnecessary expenditure, I know, but one I think I can at least partly justify.

From what I've experienced so far, I can lean on the REAR brake far more than than I can on any solo bike. In fact, for all I care, I could do without a rear brake on a solo bike in all but technical terrain, but it's evident I NEED a good rear brake on this tandem.

Given that we're new, and the hills 'round here are steep or long and sometimes both, I want the brakes to be as abuse-proof as I can get them.

Unfortunately, I won't have any comparisons to offer, other than to the Magura rim brakes, but it seems that's how I do things some times.

I'll be sure to follow up with some thoughts in a couple of weeks, once we get the disc upgrade rolling!


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## TandemNut (Mar 12, 2004)

Hayes has (supposedly) a 9" rotor kit available this year, which would work with the Avids, since the appropriate adaptor is included. We've had some on order for some time with Hayes, but so far no dice.
Magura's large rotor is 210mm, not 203mm, and won't work with an Avid brake. The 210mm rotor rubs the Avid caliper body (we already tried it). Hope's large rotors are 203mm and will work with an Avid caliper.
Whether the Avid needs additional heat dissipation is a good question. Heat building doesn't seem to be the greatest concern with the Avids. More sheer grunt in braking power would seem to be a more immediate need. Upsizing the rotor would help with that.
The other thing to keep in minds is that the larger rotor increases the leverage on the fork by offsetting the caliper further out from the hub center. 
With most forks already approved for tandem use, I don't think it's that big of an issue, but something to be considered nonetheless. Not sure if the manufacturers of the respective forks have or will sign off on the larger rotor thing. 
Of course, Santana has their 10" rotor kit for the Winzip mechanical disc. Same idea, but too bad the brake's not that good. 
I'll check again on the 9" rotor kit. That sounded like a good, simple upgrade for the Avids. 9" would be about 229mm or so.


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## Brown_Teeth (Jan 15, 2004)

200+rotor on a QR front axle? LOL You are gonna snap off those drop outs, get a real fork and then get the beefo rotors.


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## sparrow (Dec 30, 2003)

I think Speedub has a through-axle double clamp fork on the way. The Cannondale fork is on the way out...


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## Speedub.Nate (Dec 31, 2003)

BigNut said:


> Whether the Avid needs additional heat dissipation is a good question. Heat building doesn't seem to be the greatest concern with the Avids. More sheer grunt in braking power would seem to be a more immediate need. Upsizing the rotor would help with that.
> 
> The other thing to keep in minds is that the larger rotor increases the leverage on the fork by offsetting the caliper further out from the hub center.
> 
> With most forks already approved for tandem use, I don't think it's that big of an issue, but something to be considered nonetheless. Not sure if the manufacturers of the respective forks have or will sign off on the larger rotor thing.


I've read descriptions of the Avids getting hot enough to melt the red adjuster knobs. But I've also read comments by many who have heard of this, but not yet seen it -- including Avid/SRAM, who asked to be sent one of the melted knobs for investigation (I may have found that on the DF forums).

Either way, I recognize the importance of heat dissipation. Years ago, when Avid first made the adapters available, I switched from a front 165 to a 185 rotor. The 165 gave me good braking power, but would overheat and sing on long decents. Pretty soon it turned a nice rainbow color from the overheating. The 185 rotor, with its extra material, instantly eliminated the problem. I never felt I needed the extra stopping power the 185 brought with it.

Seems like many tandem riders swear by Magura's Gustav brakes, calling them the most powerful tandem brake available. My uneducated guess is if a fork can handle a mighty Gustav paired with a 203mm rotor, than a lowly Avid mechanical combined to a 220mm shouldn't be any more stressful to the fork.

If I don't post back after I complete the installation, you all are free to assume something went horribly wrong!  (And please dispatch a search party.)

Brown_Teeth, thanks for your concern. I should have mentioned at the start that the fork situation is handled.


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## TandemNut (Mar 12, 2004)

The Avid brake melting the adjusting knob was directly from Santana's anti-disc brake propaganda. I don't recall ever seeing or actually hearing about a melted adjuster knob other than from Santana. No one at SRAM had seen one when I asked them about it.
However, it's entirely possible:
We used to use plastic ferrules with the long extended tips on them for brake cables, as the tips helped keep the cables cleaner. We had one customer that called me to tell me that they got the brakes so hot the tip actually melted onto the cable, making the cables diffucult to pull. 
Hindsight is a pretty good teacher. We use metal ferrules now, even if they don't keep the cables as clean. 
But it goes to show you just how hot the caliper is getting.


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## Speedub.Nate (Dec 31, 2003)

BigNut said:


> The Avid brake melting the adjusting knob was directly from Santana's anti-disc brake propaganda. I don't recall ever seeing or actually hearing about a melted adjuster knob other than from Santana. No one at SRAM had seen one when I asked them about it...
> 
> ...But it goes to show you just how hot the caliper is getting.


Thanks, Alex. Good to hear from a reliable source! Another problem is if the calipers got hot enough to melt plastic, the grease lubricating the actuation arm's ball bearings might soon be vaporized!

Not too long ago, I had a nice reminder of how hot disc brakes get imprinted on the palm of my hand . I'm going to have fun with these. There's something about that new-brake oily burn-in smell that gets me all revved up.


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## Speedub.Nate (Dec 31, 2003)

BigNut said:


> Hayes has (supposedly) a 9" rotor kit available this year, which would work with the Avids, since the appropriate adaptor is included.


Ah Ha!

(Photo from MTBR's Interbike coverage).

(140mm, 160mm, 180mm, 203mm, 224mm)


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## Speedub.Nate (Dec 31, 2003)

They fit!

I've got to work out the usual spacer issues -- due to non-standard IS tabs on the Cannonale frame (tab face set too far inward from the dropout face) and from the fork (longer bolts & spacers to deal with the usual 20mm through-axle spacing issues).

Here are the rotors paired with Avid BB7 calipers.

The hub is a White Industries 145mm M16 rear (20mm White CHUB on the front end, not pictured). The frame is a 1999 Cannondale MT2000 (we took care of that 'lil color matching problem I mentioned in the first post ).


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## grawbass (Aug 23, 2004)

Speedub.Nate said:


> They fit!
> 
> I've got to work out the usual spacer issues -- due to non-standard IS tabs on the Cannonale frame (tab face set too far inward from the dropout face) and from the fork (longer bolts & spacers to deal with the usual 20mm through-axle spacing issues).


You know they make specific adapters for 20mm forks right?


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## Speedub.Nate (Dec 31, 2003)

grawbass said:


> You know they make specific adapters for 20mm forks right?


They?


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## Speedub.Nate (Dec 31, 2003)

Hello? What did this roll off of?

Something special, I Hope.


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## [email protected] (Dec 2, 2006)

where is that from, I want one too!



Speedub.Nate said:


> Hello? What did this roll off of?
> 
> Something special, I Hope.


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## TandemNut (Mar 12, 2004)

[email protected] said:


> where is that from, I want one too!


I believe Nate got that directly from Hope UK.


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## Speedub.Nate (Dec 31, 2003)

BigNut said:


> I believe Nate got that directly from Hope UK.


Yep, actually ordered through Hope USA in Conroe, outside of Houston.

I was pretty giddy when I got it, however, I have trouble recommending them. Phil, their customer service guy, is horrible, totally non-communicative, and really left me with the feeling he was doing me a huge favor to order this rotor for me, and jammed me up with a bunch of unnecessary busy work despite me sending him Rohloff's drawings for the mounting pattern (which Hope has, because I've ordered custom Speedhub rotors from them in the past).

In any case, I asked for 2.0, I got a 1.8. I asked for as much "extra material" as possible citing tandem usage, got a "you'll get what you get" for that. I asked for the "bubble" pattern you see here and had to go behind the US guy's back and email Hope's owner/president Ian in the UK to make that happen, because Phil ordered the standard round design.

After the fact, I whined a little to Hope UK, but I don't think they cared much. Hope UK later told me that they only do 1.8mm. The US guy could have saved me some bother had he mentioned that when I asked (I've got a whole unbelieveable chain of emails confirming 2.0 or thicker).

In general, a big pain in the butt to deal with. At least it was cheap at $45, though I imagine they undercharged me.

I'd suggest first contacting Galfer with a custom request (they do custom, but my recent email to them bounced), and also Dirty Dog (he's expressed a desire to work with Rohloff in quantity, but I don't know if he does one-off custom stuff). I'd even contact AustraliaSigns who have a great laser cutting video on YouTube.






There must me others. If none of those pan out, I'd sooner step down to a stock 208mm rotor than deal with Hope's bullshit again!


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