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Really large disk brake rotors

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Really large disk brake rotors

Old 09-23-19, 12:08 PM
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Larry Lem 1
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Really large disk brake rotors

I see Santana has 10" rotors but they cost $180. (Gen 4 from Precision Tandems). There is a monster disk brake rotor at 255 mm from BicycleDesigner available at Amazon for $69, but they designed it to be an odd shape for some reason. Are there any other rotors out there larger than 203 mm? I'd try adapting a motorcycle disk but they run about .200" thick. I measured my 203 mm disk at around .075" thick.
Thanks
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Old 09-24-19, 09:06 AM
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What year is your tandem? Some of the Santanas around 2004 use 203mm discs (if you're lucky). I looked for 10" rotor alternatives (and found the same one you did), but eventually realized that my Santana was spaced for 203mm rotors. that simplified things considerably, as I could use Shimano ice tech rotors. They have been great.
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Old 09-24-19, 09:21 AM
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Originally Posted by Larry Lem 1 View Post
I see Santana has 10" rotors but they cost $180.
Do you even know if (probably not) your fork is rated to take a monster sized rotor? They aren't all up to the stress. Plus I would think that tires start to be a limiting factor in ultimate stopability even with 'normal' sized rotors. Most riders don't need more powerful brakes, they need to ride 3 to 6 seconds ahead of their brakes. Even the motorcycle riders have to do that, they ride 12 seconds ahead of their .200" thick rotors!
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Old 09-24-19, 11:31 AM
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Santana's, up until this year, had disc brakes only on the rear.
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Old 09-24-19, 12:13 PM
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I don't have a tandem. I race streamliners at the World Human Powered Speed Challenge in Nevada each September.
I was thinking of changing from a 406 front wheel that has a disk brake to a 650c wheel with a rim brake. I want to use that brake very minimally so as not to blow the tire. I'll be depending on the rear brake more. The rear brake is 406 wheel with a 203 mm disk. The dropouts are bolted to brackets that are bonded to the inside of the shell. As I may use a stronger rider who will go faster and require more braking during the 3/4 mile-long shutdown area, I want to increase the brake size in the rear for more heat capacity (not braking power). I do not have machining capability to make a dual disk rear hub and am looking for alternatives such as larger rotors.
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Old 09-24-19, 02:05 PM
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Galfer is currently offering 223mm x 2.0mm rotors. Hope made 225mm floating rotors for a while... might be some old stock out there. TRP is rumored to have some 223mm x 2.3mm rotors coming soon.

Risse Racing offers a number of dual-disc front hubs. You might consider using rim AND disc brakes on the same wheel.
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Old 09-24-19, 05:53 PM
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The bigger the rotor, the less the stress placed on the hub and wheel mountings (not more.) The rim is the biggest possible disc, right?
Good luck and success with your streamliner racing. Most of us just think about how you guys squeeze out more speed -- but the rider has to be thinking, OK, now how do I get this thing stopped?
Would a parachute help? I suppose it adds more complexity than it's worth maybe?
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Old 09-24-19, 08:33 PM
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225mm Hope rotors

This photo shows the 225mm Hope rotors we put on our new tandem (a Ritchey Breakaway). They are great. When the calipers are adjusted correctly, we can slide the rear wheel, which is more braking than you need. This is with mechanical calipers.

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Old 09-25-19, 11:50 AM
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Originally Posted by MikeAndJean View Post
This photo shows the 225mm Hope rotors we put on our new tandem (a Ritchey Breakaway).
Looks great! What mount do you use in the rear to fit that rotor? Add something to a 203mm mount?
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Old 09-25-19, 04:17 PM
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Yes, pictures being worth the proverbial kilo-words, here is a photo. Note the additional spacers directly between the caliper itself and the mounting.

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Old 09-25-19, 06:18 PM
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Originally Posted by MikeAndJean View Post
Yes, pictures being worth the proverbial kilo-words, here is a photo. Note the additional spacers directly between the caliper itself and the mounting.
Thanks. What brand/size is that top bracket? And how thick the spacers?
I'm temped to try this on our Co-Mo Speedster with TRP HY/RD+Ice Tech rotor, which is better than the old BB7 but still not stoppy enough for my tastes.
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Old 09-25-19, 08:58 PM
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Sorry but the middle piece, which appears black in this photo, has no part number or markings of any kind. I bought it at the local bike shop because it "looked" about right. Of course, it wasn't quite right. I had to add the spacers, which I measure to be 0.112 inches. As you probably recognized from the photo, the lower part, which appears dark grey in this photo, is a standard Shimano mount for 203mm rotors.

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Old 09-26-19, 12:51 AM
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I spotted a 254mm rotor while wandering around Eurobike, branded as Now8. You can see it in their catalog on page 180 (or N21) with an adapter. They seem to have an online store that shows the rotor for 99 euros and the adapter for 18 euros. Unfortunately, I have no other knowledge about this brand.

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Old 09-26-19, 06:38 AM
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That sure looks like a dead ringer for the Santana Gen 4 rotor (pictured below)!
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Old 09-26-19, 06:50 AM
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Originally Posted by MikeAndJean View Post
This photo shows the 225mm Hope rotors we put on our new tandem (a Ritchey Breakaway). They are great. When the calipers are adjusted correctly, we can slide the rear wheel, which is more braking than you need. This is with mechanical calipers.
I didn't realize Ritchey makes tandem frames! I have a breakaway cross and really like the idea. Does it pack into 2x suitcases?
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Old 09-26-19, 08:10 AM
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Thread drift

Originally Posted by riceowls View Post
I didn't realize Ritchey makes tandem frames! I have a breakaway cross and really like the idea. Does it pack into 2x suitcases?
It fits into two bags, one the same size as used for a Breakaway single. The second bag is slightly larger.
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Old 09-26-19, 05:48 PM
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Is this yours? How thick is that rotor?

Originally Posted by Joint Venture View Post
That sure looks like a dead ringer for the Santana Gen 4 rotor (pictured below)!
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Old 09-26-19, 05:59 PM
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Yes, itís our old 2001 Santana Sovereign tandem that we sold almost a year ago. Iím not sure how thick the braking surface is, and canít measure since itís gone, but the braking surface did not seem noticeably thicker than the Santana Gen 3 254mm one-piece steel rotor and the Avid 203mm rotor that preceded it.
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Old 09-27-19, 11:53 AM
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Originally Posted by Joint Venture View Post
Yes, itís our old 2001 Santana Sovereign tandem that we sold almost a year ago. Iím not sure how thick the braking surface is, and canít measure since itís gone, but the braking surface did not seem noticeably thicker than the Santana Gen 3 254mm one-piece steel rotor and the Avid 203mm rotor that preceded it.
I recognized that tandem! Looks just like our 2000 Sovereign. I'm just wondering if the rotor is slim enough to fit in our HY/RD caliper; current disc is 1.8mm thick, I believe.
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Old 09-27-19, 12:21 PM
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Originally Posted by sapporoguy View Post
I recognized that tandem! Looks just like our 2000 Sovereign. I'm just wondering if the rotor is slim enough to fit in our HY/RD caliper; current disc is 1.8mm thick, I believe.
I canít imagine it wouldnít work!
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Old 09-30-19, 02:33 AM
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Originally Posted by sapporoguy View Post
I recognized that tandem! Looks just like our 2000 Sovereign. I'm just wondering if the rotor is slim enough to fit in our HY/RD caliper; current disc is 1.8mm thick, I believe.
They sell exactly the same rotor in sizes down to 160mm, so I can't imagine it's any thicker than standard. I also zoomed in on the originals of the photos that I took at Eurobike, the thickness is not marked but it looks to be pretty normal.
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Old 10-01-19, 08:39 AM
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i have the bicycle designer one on one of my stretch cruisers (just on the front. still need to build the rear wheel to add the other). if you're meaning the outer flat sides, i think if the caliper is positioned well the contact area stays consistant. at least as best i can tell, as i welded the caliper mount on myself. in any event it seems to work well by it's self with no rear at the moment, also considering it's a pretty heavy bike (started with a coker monster), but i'll qualify that by adding it's a cruiser that doesn't see very high speeds.
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Old 10-08-19, 11:45 AM
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Presumably under sustained braking (long downhill, for example), you'd have the rotor heating up, but, regardless of how big the rotor is, you'd also have the brake pads and housing heating up. It may be that they're already at the point where bigger rotors don't really accomplish much.
Mounting two brake units on a single rotor might help keep the heat down if you didn't just twist the rotor into a pretzel.
Intentionally shifting airflow to the brake might accomplish more- something along the lines of a hood scoop on an HPV.
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