Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

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!

User Tag List

Reply
 
Thread Tools Search this Thread
Old 08-13-09, 05:53 AM   #1
Amesbub
Junior Member
Thread Starter
 
Join Date: Aug 2009
Location: Ruthin, North Wales
Bikes:
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Mechanical discs vrs V-Brakes

Not long bought our Cannondale Road 3 tandem, which we're really pleased with. But as per usual, can't resist changing bits, mainly to save weight. I'm thinking of ditching the Avid mechanical discs what were fitted originally and using Shimano XTR v-brakes. Just wondered if this is a big mistake and we'd struggle to stop on steep descents? Our combined weight is a little less than 300lbs. Your thoughts are most welcome.

Last edited by Amesbub; 08-13-09 at 06:01 AM.
Amesbub is offline   Reply With Quote
Old 08-13-09, 09:01 AM   #2
specbill
Riding Heaven's Highwayson the grand tour
 
Join Date: Sep 2007
Location: Tehachapi Mtns, Calif.
Bikes: '10 C'Dale Tandem RT2. '07 Trek Tandem T2000, '10 Epic Marathon MTB, '12 Rocky Mountain Element 950 MTB, '95 C'dale R900, "04 Giant DS 2 '07 Kona Jake the Snake, '95 Nishiki Backroads
Posts: 737
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Welcome to the forum and congrats on the new C'dale.
Your question is a very popular one that has been asked in various ways and covered hundreds times here. IF you play with the 'search function' a little you will be reading for days...Ultimately you will find that people swear by both for different reasons. Both are good, but your priorities, where and how you ride, along with your past experiences will probably define what will be best for you...Have fun and enjoy the ride.

Bill J.
specbill is offline   Reply With Quote
Old 08-13-09, 09:56 AM   #3
rdtompki
Senior Member
 
rdtompki's Avatar
 
Join Date: Nov 2008
Location: Hollister, CA
Bikes: Volagi, daVinci Joint Venture
Posts: 3,962
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I wouldn't bother to change. Let's say total weight of team and bike is 350 lbs full up. A 10 mph climb ignoring aero effect woud net you a speed increase of .03 mph assuming a 1 lb weight penality for the disc. I supposed a disc has more aero drag than a v-brake so there might be a penalty at high speed, but I have no idea what that would be.
rdtompki is offline   Reply With Quote
Old 08-13-09, 11:37 AM   #4
DCwom
Senior Member
 
DCwom's Avatar
 
Join Date: Jan 2009
Location: Central New Jersey
Bikes: Burley Tandem
Posts: 344
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
My 2 cents, about what its worth since we don't do hills...

We have v-brakes, and I wish I had a disc to drag on the rear, not that we're climbing hills large enough to overheat our rims, but I'm just paranoid about it. Every time we experience a new down hill I think how long is this, will this be a hill worthy of stopping to check the rims? As for the weight, if I was concerned about another pound on the frame, I'd go on a diet, which of course would reduce the chance of my rims heating...
DCwom is offline   Reply With Quote
Old 08-13-09, 12:19 PM   #5
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Rans Rockst (Retro rocket) Rans Enduro Sport (Retro racket) Catrike 559, Merin Bear Valley (beater bike).
Posts: 26,501
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Oh good! I thought that I was the only guy left who wasn't enchanted with disc brakes. If my Noventa had a place to put it, I'd ditch my WindZip rear disc and stick on an Avid SD7.

Having said that, if you are dissatisfied with the stopping power of your mechanical discs, hunt up some compressionless BRAKE housing. It's out there and it makes a huge difference.
Retro Grouch is offline   Reply With Quote
Old 08-13-09, 01:32 PM   #6
WebsterBikeMan
Senior Member
 
WebsterBikeMan's Avatar
 
Join Date: Jun 2008
Location: Just outside Kitchener, Ontario
Bikes: Nishiki Continental, Bilenky custom travel tinker, home built winter bike based on Nashbar cross frrame
Posts: 622
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Alternatively, if you do want to switch, you might want to wait until it's time to change the pads anyhow. Struggling to stop isn't the issue on steep descents. The question is whether you overheat while avoiding going faster than you wanted. That's where drag brakes come in. Touring, we come in at around 400 including riders, bike, 60 lbs gear, and 3l water. We managed to stop after coming down from the Watkins Glen Campground (60m drop, 400m horizontal with stretches of 20% with a speed limit 25 mph, and a stop sign at the bottom). The problem was avoiding exceeding the speed limit by too much without overheating the rims. Mind you we do have Aeroheat rims, which seem to be better than some as far as that goes.

Much depends on what you mean by steep.
WebsterBikeMan is offline   Reply With Quote
Old 08-20-09, 07:55 AM   #7
Brian
Senior Member
 
Brian's Avatar
 
Join Date: Nov 2004
Location: Between the mountains and the lake.
Bikes: 8 bikes - one for each day of the week!
Posts: 16,683
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
So you want to switch from tandem rated discs to XC racing brakes?
Brian is offline   Reply With Quote
Old 08-20-09, 10:23 AM   #8
justcrankn
Senior Member
 
Join Date: Dec 2007
Location: Minneapolis, MN
Bikes: Trek T2000, Ventana ElConquistador, ElSanto, STP400, 5500, JubileeSport, Scattante...
Posts: 144
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Brian View Post
So you want to switch from tandem rated discs to XC racing brakes?
Just to be clear, the last time I checked with Avid their discs were not approved for tandem use. I've gotten better performance with rim brakes than disc, but my Avid disc may have been defective. You could shave some real weight by installing a carbon fork (Reynolds or Alpha Q) with a caliper brake.
In a previous post you have a picture of some wet riding. The discs will work better when wet.
justcrankn is offline   Reply With Quote
Old 08-20-09, 10:27 AM   #9
Brian
Senior Member
 
Brian's Avatar
 
Join Date: Nov 2004
Location: Between the mountains and the lake.
Bikes: 8 bikes - one for each day of the week!
Posts: 16,683
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by justcrankn View Post
Just to be clear, the last time I checked with Avid their discs were not approved for tandem use.
What's your source? When I put them on my tandem MTB, I did so because they were the only mechanical discs rated for tandem use.
Brian is offline   Reply With Quote
Old 08-20-09, 10:56 AM   #10
TandemGeek
hors category
 
TandemGeek's Avatar
 
Join Date: Jan 2002
Bikes:
Posts: 7,208
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Brian View Post
What's your source? When I put them on my tandem MTB, I did so because they were the only mechanical discs rated for tandem use.
I believe the pendulum has swayed back and forth a bit over the years.

1. The Avid's were initially not endorsed for use on tandems when they first were introduced and Avid was still Avid (late 90's).

2. After some extensive use of the BB7s on both off-road and road tandems with excellent results and no safety issues by a well-respected tandem builder co-located in the same part of the same Colorado town, Avid BB7s were spec'd as OEM brakes on Cannnondale's 2004 RT3000 tandems shown at the '03 Interbike and were shortly thereafter offered as an optional front and/or rear brake on Co-Motion's tandems. The Avid's came with the following caveats: (a) only when used with the 203mm rotor, and (b) only when used as a direct replacement for a primary rim brake. The latter basically said, these are as good or better than rim brakes but they're not suitable as a drag brake replacement for the Arai drum. None of this was covered in any literature, it was communicated they way most technical information was within the tandem community via OEM endorsement and one-on-one phone calls with Avid's tech dept.

Note: Bear in mind that you won't find any rim brakes that are "rated" for tandem use either.

3. During Interbike '03 (when Cannondale showed up with the '04 model-year Avid-equipped RT3000) a certain OEM builder who chose not to offer Avids began a subtle campaign to label the Avid's as not being tandem-rated and went to far as to suggest that C'dale was putting itself at risk by spec'ing the Avids. Given that to this day some 5 years later (or thereabouts) Cannondale with all of it's corp. lawyers and past liability issues on early frame failures still spec'd the Avid's so take that for what it's worth. Similarly, Co-Motion, daVinci and a few other builders also offer the Avid as an optional primary brake on road and/or off-road and enduro tandems.

4. When SRAM acquired Avid the tandem endorsement didn't seem to carry over to the new company's marketing or tech departments in their list of approved answers to FAQs.

Again, there's not much in the way of bicycle components that are designed for use on tandems and/or that carry tandem endorsements. Therefore, we look to the OEMs and early adopters of new component offerings to find out what seems to work and what doesn't. Thus far, Avid's BB7 discs with the 203mm rotors have enjoyed a pretty darn good track record with any "failures" being limited to melted adjustment nobs (not a critical component) or other types of failures such as brake fade or warped discs that are on par with the problems teams have when they push rim brakes beyond reasonable expectations, e.g., loads, conditions or method of use.

Last edited by TandemGeek; 08-20-09 at 11:01 AM.
TandemGeek is offline   Reply With Quote
Old 08-20-09, 11:03 AM   #11
justcrankn
Senior Member
 
Join Date: Dec 2007
Location: Minneapolis, MN
Bikes: Trek T2000, Ventana ElConquistador, ElSanto, STP400, 5500, JubileeSport, Scattante...
Posts: 144
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Brian View Post
What's your source? When I put them on my tandem MTB, I did so because they were the only mechanical discs rated for tandem use.
Phone call several years ago. My LBS called and they wouldn't offer any support for a tandem. Here's their contact page http://www.sram.com/en/about/contact.php if you want to call.
I have no doubt that the Avid would be the best choice for a road disc, but that doesn't make it "tandem approved".
IIRC Avid did approve them for awhile. Searching the archives might pull up more info.
justcrankn is offline   Reply With Quote
Old 08-20-09, 11:04 AM   #12
Brian
Senior Member
 
Brian's Avatar
 
Join Date: Nov 2004
Location: Between the mountains and the lake.
Bikes: 8 bikes - one for each day of the week!
Posts: 16,683
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I read that test years ago where brakes melted and fluid boiled, and Avids came out on top.

[edit] I have reliably used them on a tandem with 350+lbs of captain/stoker.
Brian is offline   Reply With Quote
Old 08-20-09, 03:40 PM   #13
John R
so cal com
 
John R's Avatar
 
Join Date: May 2008
Location: Yorba Linda Calif
Bikes: Trek hybrid commuter, Specialized Tarmac, Cannondale Cad 6, Shwinn Homegrown MB, Specialized FSR MB Cannondale Tandem
Posts: 419
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I did Everest Challenge on 07 with Avid shortys cantis with no problems.
John R is offline   Reply With Quote
Old 08-21-09, 07:56 AM   #14
DKMcK 
I'd rather be riding
 
DKMcK's Avatar
 
Join Date: Sep 2008
Location: Charlotte NC
Bikes: Santana Team Ti 700 S&S, Trek Madone 6, Klein Palamino, Trek 510
Posts: 107
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I purchased my 05 Cannondale last year from someone who had already done the weight reduction upgrades (carbon fork, Avid shorty breaks, lighter wheels, and a few others). Our Cannondale weighs in at just over 34lbs. He also threw in the removed components in the deal. I'm really happy with how the bike rides. I did replace the Avid Shorty on the rear with a v-break, the shorty just did not work well with the long cable. We had some long descents on the Bike Virginia ride this year and I was wondering if I should have but the discs back on. I never felt like i could not stop but was concerned about heat buildup. Probably more worry than reality. We do not live in the mountains and my stoker has made it very clear we're not riding in the mountains, so this setup works great for us. I suspect the carbon fork is the best "bang for the buch" upgrade. It saves weight and improves the ride.
DKMcK is offline   Reply With Quote
Old 08-21-09, 11:45 AM   #15
uspspro
Tandem Mountain Climber
 
Join Date: Mar 2007
Location: San Mateo, CA
Bikes: Calfee Tandem, Custom CAAD9 BB30, 90 Santana Arriva Tandem, 02 CAAD4 errand bike, 87 Cannondale "Black Lightning"
Posts: 4,101
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by John R View Post
I did Everest Challenge on 07 with Avid shortys cantis with no problems.
Tandem or solo?
uspspro is offline   Reply With Quote
Old 08-22-09, 02:19 AM   #16
reohn 2
Junior Member
 
Join Date: Jun 2006
Bikes:
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
We have a Santana Arriva with V's t/agents (Koolstop dual compound pads)and STI's on drops, third brake is an Arai,the Arai is a boon in the big hills and the V's very good.
Earier this year we bought a Cannondale Road tandem(C/dale only sell the disc equiped tandem in the UK)mainly as a winter bike to save on rims, the stopping power of the Avid BB7's is awesome in comparison with the V's and in the wet there is simply no contest, discs win hands down.
The Santana will still be used on tours in the mountains where the Arai drag comes into its element but I'm very impressed with the discs.
reohn 2 is offline   Reply With Quote
Old 08-23-09, 08:25 PM   #17
sch
Senior Member
 
Join Date: May 2003
Location: Mountain Brook. AL
Bikes:
Posts: 2,963
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Cantis work at least as well as BB7 discs with 203mm rotors and weigh ~120z per wheel less. We put
a disc rear on ours when we found the wheel rim too hot to touch at the end of rides to my house
when we braked from 35mph to 0 over ~200 yds with an elevation change of ~40'. There aren't any
local hills longer than 2mi and the longest down hill in the state is perhaps 10mi, but this is a roller
coaster. If your riding does not significantly heat the rims and does not involve a lot of water on
the rims the cantis should be adequate. In our experience the BB7 pads last about 5 kmile, at a
replacement cost in the $12-15 range. Canti pads last a lot longer, but off road riding will abrade
the rims away over time.
sch is offline   Reply With Quote
Old 08-23-09, 10:15 PM   #18
base
Junior Member
 
Join Date: Jan 2008
Bikes:
Posts: 22
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Amesbub, if you convert to V brakes, can I buy your Avid discs? I just bought a Cannondale with V brakes and want to convert the other way (mainly because I'm converting the bike to 650b).
base is offline   Reply With Quote
Old 08-29-09, 09:45 PM   #19
John R
so cal com
 
John R's Avatar
 
Join Date: May 2008
Location: Yorba Linda Calif
Bikes: Trek hybrid commuter, Specialized Tarmac, Cannondale Cad 6, Shwinn Homegrown MB, Specialized FSR MB Cannondale Tandem
Posts: 419
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
On a Cannondale Tandem...
John R is offline   Reply With Quote
Old 09-02-09, 08:04 PM   #20
TwinBicyclesNY
Twin Bicycles
 
TwinBicyclesNY's Avatar
 
Join Date: Sep 2009
Bikes: 2009 Trek Fuel Ex 6.5, MirraCo Black Pearl 3
Posts: 11
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
As a store owner, it will mainly depend on what kind of weather riding style you guys will be doing. If you ride your tandem all day every day every weather then i would keep the disc brakes on and ditch the XTRs. If you only happen to ride when most normal people ride in a beautiful weather settings, you can go either or. Of course the XTRs will help in saving weight on your bicycle. IMO, disc brakes and v brakes are pretty much the same in the sunny, dry conditions. I hope this helps and keep on riding.
TwinBicyclesNY is offline   Reply With Quote
Old 09-08-09, 07:32 PM   #21
zonatandem
Senior Member
 
zonatandem's Avatar
 
Join Date: Dec 2003
Location: Tucson, AZ
Bikes: Custom Zona c/f tandem + Scott Plasma single
Posts: 10,837
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Save some weight . . .
Keep rear disc and V-brake up front.
zonatandem is offline   Reply With Quote
Old 09-08-09, 07:49 PM   #22
merlinextraligh
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Bikes: Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er; Calfee Dragonfly Tandem
Posts: 29,108
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Quote:
Originally Posted by Amesbub View Post
. Just wondered if this is a big mistake and we'd struggle to stop on steep descents?
The issue isn't stopping power. Good rim brakes will stop a tandem as well as discs. Once you have the power to lock the wheels (and modulate short of that) brakes can't give you anymore stopping power.

The issue is heat. Lots of braking on steep descents can overheat rims,a nd lead to tire failure. The likelyhood of this depends on 1) the total weight (including bike, riders, and cargo, 2) the terrain, and 3) riding style.

For us, at a team wieght around 350lbs, we've found rim brakes adequate even in steep and long descents. But we tend to descend fast, and only brake for turns, which allows the brakes to cool between turns. If you want to control your speed more, and are riding technical terrain, you might want discs.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
merlinextraligh is offline   Reply With Quote
Old 09-09-09, 07:53 AM   #23
WebsterBikeMan
Senior Member
 
WebsterBikeMan's Avatar
 
Join Date: Jun 2008
Location: Just outside Kitchener, Ontario
Bikes: Nishiki Continental, Bilenky custom travel tinker, home built winter bike based on Nashbar cross frrame
Posts: 622
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by merlinextraligh View Post
The issue isn't stopping power. Good rim brakes will stop a tandem as well as discs. Once you have the power to lock the wheels (and modulate short of that) brakes can't give you anymore stopping power.
+1
Quote:
Originally Posted by merlinextraligh View Post
The issue is heat. Lots of braking on steep descents can overheat rims,a nd lead to tire failure. The likelyhood of this depends on 1) the total weight (including bike, riders, and cargo, 2) the terrain, and 3) riding style.
And rims and probably tires. Some rims have more mass further from the tire (Velocity Aeroheats/Aeroheads come to mind, as do Deep V's). Wire bead tires may be more likely to conduct the heat to the tube. Wider tires can absorb more heat as well. All of which are probably second order effects to the ones already listed. You have to dump a certain amount of energy, and it all goes into heat.
WebsterBikeMan is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 12:45 AM.