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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 12-03-08, 03:39 PM   #1
I_meant2do_that
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2002 C'dale RT3000

As I mentioned awhile back, I purchased a 2002 Cdale RT3000. This particular year they had the front hubs which were disc upgradeable but the forks had no tangs to mount a caliper. The previous owner put a carbon redline fork on it with cantilever stems but I wanted to be able to eventually upgrade to disc brakes. So today I ordered a newer model fork from C'dale which had the caliper mounts. (which immediately went up $60 because when I came out of the bike store the meter maid was just putting down my windshield wipers... )

SOooo........

It seems that a lot of teams/tandems have mechanical Avids mounted. Advice, input, suggestions, or should I stay with the cantilever or v-brake set up?

And if so, the previous owner did not have the original brakes on the bike, so if I stay with the rim brakes, do I go V-brake (make/model?) or Cantilevers (make/model?)

Thanks in advance.

Eric & Robyn
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Old 12-04-08, 05:22 AM   #2
mrfish
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If you can get the front wheel to skid from speed (it takes practice - do a search on Santana's postings) then you are already obtaining maximum braking from your current brake and there is little point in upgrading.

If not, then first question is whether you would use the additional power over what you have now. A disc will probably give more power, somewhat better heat disippation down long hilss and probably work better in the wet.

However it's not all free as it costs extra weight, limits wheel choice and doesn't look classic (which is important for some).

Since you already have a suitable wheel and fork I would try an Avid BB7 Road kit (Road kit has shorter lever arm to work with road STI levers). If you don't like it you can always switch back.
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Old 12-04-08, 09:12 AM   #3
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Originally Posted by mrfish View Post
A disc will probably give more power, somewhat better heat disippation down long hilss and probably work better in the wet.
IMHO, delete the red font above and you will be better describing reality.
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Old 12-04-08, 10:44 AM   #4
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I usually use the rear brakes to control my speed and for this disc brakes are great as they do not overcook your rims when you are descending and continuously using them. I've got V Brakes in the front and they give me all the stopping power I need. We are a light weight team (under 250lbs) so I cannot say if it will be the same for others as their team weight and usage of front and rear brakes might be different. If you are weight conscious and the V brakes have worked for you keep them.

As for me, I am thinking of changing my rear disc to V Brakes since I mainly ride on flat to rolling terrain and plan to put on the rear disc when we ride on a tour with hills. I do like how the disc brakes modulate and am contemplating this change as I will probably shave only about half a pound. But I like tinkering with my bikes so I guess this is a good excuse
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Old 12-05-08, 02:09 PM   #5
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Originally Posted by mrfish View Post
If you can get the front wheel to skid from speed (it takes practice - do a search on Santana's postings) then you are already obtaining maximum braking from your current brake and there is little point in upgrading.
I fail to see the advantage of getting the front wheel to skid from speed on a tandem.

Having stopping power to spare without "locking" either wheel and going into a "skid" is precisely why I like the front and rear disc brakes on our tandem.

I googled "santana tandem skid" and found this one web page:

http://santanatandem.com/Techno/MechVsHydro07.html

Is there another you were thinking of?
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Old 12-05-08, 02:28 PM   #6
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Originally Posted by CapTandem View Post
I fail to see the advantage of getting the front wheel to skid from speed on a tandem.

Having stopping power to spare without "locking" either wheel and going into a "skid" is precisely why I like the front and rear disc brakes on our tandem.
If you can stop the wheel enough to make it skid, no more powerful brake can make you decelerate faster.
Once the wheel skids, the brakes are no longer the limiting factor: it's the friction between the tire and the road.
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Old 12-08-08, 05:52 AM   #7
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OK I didn't explain very well in my original post, so here goes.

Maximum braking friction between the tyre and the road occurs when there is a degree of slip between the road and they tyre, i.e. the wheel is rotates slightly less fast than the road is moving. Friction falls off sharply once a full locked-wheel skid starts. Mathematically speaking if you draw a curve of friction versus relative wheel-road speed, there is a sharp peak just before the wheel skids, so to stop as fast as possible you need to brake hard enough to get into this zone, but not beyond.

Thus you need brakes that are strong enough to lock the wheel, but need enough skill to:
a) modulate braking to nearly but not quite skid
b) if a skid develops quickly reduce braking to get back into maximum braking zone
c) not fall off while doing this.
Note that weight transfer means that a different level of braking is possible at the front and rear of a bike (and changes with decelleration level), so it's not easy to do well. Thus practice as referred to in the Santana page I mentioned is required.

Slight aside:
ABS systems (Anti Blockier System in German = Anti Skid System) maximise braking by braking until the wheel locks, then relax the brake slightly until that the wheel rotates, then braking hard again. Thus the system keeps the braking effort close to the peak of the friction curve. A skilled racing driver on a dry surface can thus outbrake an ABS system by knowing exactly where the peak is and braking to that level. However on surfaces with unknown or variable friction an ABS system will be far superior as it modulates each wheel individually. This is effectively what you're trying to do on a bike or non ABS equipped car by adopting cadence braking where you brake hard, release slightly then brake hard again.Other advantage is that the car still steers under braking as the wheels aren't locked.
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Old 12-08-08, 11:02 AM   #8
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We have Avid mechanical brake on the rear and V brakes on the front of two tandems. The Avid stops faster than V brakes, does not over heat the rims on long descents, and is much better in the rain. The Avids have a tight clearance between the pad and rotor and can be touchy to adjust. Removal of the wheel may require readjustment of the brake so if you remove the front wheel to haul your tandem it is a consideration. The second Avid problem is that a rotor is sometimes not flat (has a slight wobble in it.) This causes the rotor to rub on the brake pad with each rotation. Last week we had a rotor replaced and the shop tried two Avid rotors and both were not flat. The mechanic put on a Hayes rotor because it was flat. It will be interesting to see how it works but our Hoosier is too cold!
Sheldon
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Old 12-08-08, 04:57 PM   #9
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Thank you for the replies thus far. Being a former motorcycle competitor, I am very much aware of the front wheel skidding.

Also, thanks to those regarding the Avid mechanicals. tandem rider, thank you for the information regarding the rotors. The forks should be coming in this week.

So I am assuming that V-brakes have a big following as well over the cantilevers.

Just trying to keep my better half safe, short of having a different Captain...lol.

Regards
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Old 12-09-08, 08:23 PM   #10
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""So I am assuming that V-brakes have a big following as well over the cantilevers.""


' Switched from front and rear Canti's to front and rear V Brakes (Avid SD-7's) two years ago on our older C'dale. While both setups stop our tandem well enough in most situations I prefer the Avid's. They have better feel/modulation and get the job done a bit more smoothly. These brakes, in combination with 28c Continental GP 4-Season tires, are confidence inspiring when it comes time to extend the bike a bit. We are a 310 pound team.

Bill J.
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Old 12-17-08, 05:30 PM   #11
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yippee!! My fork arrived today....what ta do?! what ta do?!
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