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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 09-21-09, 07:44 AM   #1
rmac
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Reason Against Rear Disc

So we were at mile 63 in a century. We were starting up after a rest stop. There was a guy beside us starting up. All of a sudden he falls over knocks our bike over (we were still standing over it) and lands on our back wheel.

He managed to bend the disc brake rotor. I was able to true up the wheel. The rear derailleur was scratched up and looks a little bent but appears to shift fine. Because of the rotor we had to sag back to our car. Maybe we should carry an extra rotor?
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Old 09-21-09, 08:28 AM   #2
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Sorry to hear that.

How easy is it to bend a rotor? You're situation seems to be a relatively unlikely occurrence.

However, I'm wondering how likely such damage would be over time travelling with the bike, in and out of cars, in and out of cases?
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Old 09-21-09, 08:45 AM   #3
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It's quite easy to bend a rotor, particulary if you travel with your tandem and leave the rotor attached to the wheel...

Other thoughts...

1. We gave up on 'fund raiser rides' long ago because of the inherent hazard of riding with folks of questionable skills and, well, simply the law of averages associated with being around that many cyclists, any one of which could have a bad day that ruins my day.

2. Organized centuries often times reach the same level of controlled chaos.... we're careful to pick and choose which rides to attend, when to leave the start area and/or which end of the pack to be in.

3. Unless you're riding in challenging terrain where you need both brakes, the easy way home with a bum rotor or disc brake is to take the rotor off and take it easy.
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Old 09-21-09, 08:45 AM   #4
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However, I'm wondering how likely such damage would be over time travelling with the bike, in and out of cars, in and out of cases?
When packing the rear wheel for travel in a case you should remove the disc from the rear wheel.
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Old 09-21-09, 08:48 AM   #5
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Wow! That seems like a case of incredibly bad luck. I've been more concerned about our rear disk the few times we've had the wheel off and packed in a wheel bag while traveling than I ever have been while it's on the bike.

I personally wouldn't be concerned about another mishap like that happening again....
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Old 09-21-09, 09:09 AM   #6
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rmac...sorry about the rotor....with that kind of luck don't waste your money on any Lotery tickets this week.

We really enjoy traveling to new areas for Organized Rides and do a lot of them. For sure they can be a scary crap shoots at times. We have had a few close ones and are really on high alert particularly early on at the big ones.

Bill J..
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Old 09-21-09, 09:21 AM   #7
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We really enjoy traveling to new areas for Organized Rides and do a lot of them. For sure they can be a scary crap shoots at times. We have had a few close ones and are really on high alert particularly early on at the big ones.
Probably a topic for a new thread, e.g., the hazards of riding a tandem at large organized rides.... didn't mean to interject a hijack.

Back to the rotor, they do warrant some extra attention to be sure. Minor warps aren't all that hard to un-do but yeah, if someone falls on one or if they truly get bent you're SOL.
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Old 09-21-09, 12:19 PM   #8
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It's quite easy to bend a rotor, particulary if you travel with your tandem and leave the rotor attached to the wheel...

Other thoughts...

3. Unless you're riding in challenging terrain where you need both brakes, the easy way home with a bum rotor or disc brake is to take the rotor off and take it easy.
I thought of just removing the rotor, but having done this century before, I knew the big hills were in the last 15 miles. While not having any technical descents, it is not real flat. We had about 2300 ft of climbing at 63 miles. Now I'm thinking we could have taken a short cut back that would have avoided the rest of the hills.

We always remove both rotors when the bike is packed on the advice of a thread here.

The derailleur is a Record long cage 10sp which are no longer sold. If the cage is not bent can I buy a new one and change the pully cage?

I'll respond to about large rides and tandems in the new thread. For some reason though, even though there were probably 800 people on this ride not many did the full 100. Seems in the past there were a lot more. This problem, I think, is more riding with inexperienced riders.
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Old 09-21-09, 07:36 PM   #9
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Good luck for finding a cheap one [Campy Record]. The newer versions were carbon fiber, that one may have broke [but maybe it would have survived]. Keep an eye out and maybe you can find one on eBay but it will not be cheap.
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Old 09-22-09, 07:56 AM   #10
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If the cage is not bent can I buy a new one and change the pully cage?
I've had a few older versions fully disassembled before and I'm fairly certain you can still cannibalize the more recent models of Campy rear derailleurs but the donor and patient need be of the exact same design / generation.

Best bet is to look for a used short or med length used RD of the same vintage; they're out there.
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Old 09-22-09, 10:38 AM   #11
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"The rear derailleur was scratched up and looks a little bent but appears to shift fine"

If the bent derailleur did not shift would this be a reason to not use derailleur also?
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Old 09-22-09, 03:43 PM   #12
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"The rear derailleur was scratched up and looks a little bent but appears to shift fine"

If the bent derailleur did not shift would this be a reason to not use derailleur also?
That would be as pretty good reason. The derailleur cage does not look like it's perpendicular to the ground. It seems to be bent in a little towards the wheel. Amazingly, it seems to shift fine.

The Record 10sp medium cage, which is still being sold, can handle a chain wrap of 36. The long cage could handle 39. Right now we're at 40. If I went back to a 12-27 cassette from a 12-30, we could use the medium cage derailleur.

Last edited by rmac; 09-22-09 at 03:49 PM.
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Old 09-22-09, 04:03 PM   #13
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If I went back to a 12-27 cassette from a 12-30, we could use the medium cage derailleur.
FWIW, I used a medium cage Campy Racing Triple RD on our Erickson from '98 - '02 with a 12x30t cassette because there was no such thing as a long-cage Campy RD at that time. The long-cage is actually of marginal on a tandem value because you can't really use the lower 1/2 of the cassette when you're in the granny ring which is where it would pick up that extra slack.

Just something to think about.
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Old 09-22-09, 05:19 PM   #14
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FWIW, I used a medium cage Campy Racing Triple RD on our Erickson from '98 - '02 with a 12x30t cassette because there was no such thing as a long-cage Campy RD at that time. The long-cage is actually of marginal on a tandem value because you can't really use the lower 1/2 of the cassette when you're in the granny ring which is where it would pick up that extra slack.

Just something to think about.
I think you're right that I could just use the medium cage. I have a single that has a medium cage working fine with a chain wrap of 39. With the 12-30 cassette we don't shift down to the granny unless the climb is fairly steep and never use it on the smaller 1/2 of the cassette. On our aborted century we never used it.

Now, who is going to pay for it? I'm thinking is it is just one of those costs of biking.
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Old 09-24-09, 07:39 AM   #15
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I put on a new Avid Clean Sweep disc and noticed that they changed the design. It now has a more open design and is 20% lighter. I guess this will decrease the heat capacity but maybe increase the heat dissipation to the air.
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