Carbon fiber forks for tandems.

[knehaas]

My wife and I are looking for a Carbon fiber fork for our tandem. We are riding a Cannondale RT1000 bike. Our combined weight with bicycle included is 340 lbs. I am looking for any recomendations on durability, weight, and price.
Thanks

[TandemGeek]

There are only 5 tandem-rated fork models being marketed for sale:

True-Temper's Alpha Q X2: 440gr with 1 1/8" steerer and your choice of 41mm, 44mm or 48mm rake. You must use a caliper brake arch with this fork and it will only take up to a 700x25mm size tire (although a 28mm Continental tire may fit - but it's tight). $478 MSRP
http://www.truetemper.com/performance_tubing/x2.html

Advanced Composite's Wound-Up: 800gr with 1 1/8" steerer and 45mm rake. You must use a caliper brake arch with this fork but it takes up to 700x32mm or perhaps even larger tires and mud guards. $495 MSRP
http://www.advancedcomposites.com/woundup.htm

Advanced Composite's Wound-Up Canti: 800gr with 1 1/8" steerer and 45mm rake. This fork has cantilever / linear pull brake bosses and is otherwise the same as the other Wound-Up composite fork. $525 MSRP
http://www.advancedcomposites.com/woundup.htm

Reynolds Ouzo-Pro Tandem: 500gr (claimed) and 1 1/4" steerer with 55mm rake. $599 MSRP.
http://www.reynoldscomposites.com/OuzoProTandem.html

Tange/Santana Canti Tandem Fork: 1 1/4" steerer with 55mm rake. $399 MRSP


Your RT1000 probably has a 1 1/8" steerer with 53mm of rake assuming it is one of the more recent models therefore only the Alpha Q or Wound-Up forks would work on your tandem. The Reynolds & Tange forks were designed for use on Santana tandems which use 1 1/4" steerers and 55mm rake.

So, you're left with four options:

1. Alpha Q: The 48mm rake model will increase your steering trail from the stock 2" to approximately 2.2". I say approximate since I'm not sure exactly how long your Cannondale's stock fork legs are. The Alpha Q's tend to run a little bit shorter (374mm from drop-out to crown) than most other steel or the other carbon tandem forks so by lowering the front end of the tandem the head tube angle is altered a bit. The bottom line is, the Alpha Q would have the least amount of impact on how your Cannondale handles; however, it will still alter the steering feel a bit. In short, it will feel a little more twitchy at slow speed but will feel more secure through the corners. If you've ever taken a Co-Motion tandem for a test ride it would more closely approximate the handling that you would expect to find on your Cannondale with the Alpha Q. Depending on what size frame you have and how large your feet are you may also find that you have some toe overlap with this fork. The smaller your tandem's frame the more likely this is. We have toe overlap on both of our road tandems -- actually, all of my bikes have it -- and it hasn't been an issue. But, something worth noting.

2. The Advanced Composites Wound-Up: The 45mm rake will increase your steering trail from the stock 2" to approximately 2.32". Again, I say approximate since I'm not sure exactly how long your Cannondale's stock fork legs are compared to the Wound-Up's which is 387mm from drop-out to crown. My guess is, it's pretty close. The bottom line is, the Wound-Up fork would have a more significant impact on how your Cannondale handles compared to the Alpha Q. In short, at first it will feel very twitchy at slow speed but -- as with the Alpha Q -- much more secure through the corners. Again, back to the benchmark of the Co-Motion, if you were to compare the two your Cannondale would have less slow speed stability but would also respond better to body steering / leaning inputs through the corners.

3. Advanced Composites Wound-Up Canti-Model: Same as above for the Wound-Up except it will work with cantilever or linear-pull (aka. V-Brakes).

4. Last option BUT NOT recommended: You could contact single bike carbon fork manufacturers and find out what the max weight rating is for their forks. I've been told that Reynolds basic carbon fork was designed to handle some rather high weights and loads and there are at least one or two tandem teams running around on these. However, I believe both teams are sub-300lbs which is a lot less than 340lbs when it comes to the loading that's put on these forks under heavy braking at the very high speeds tandems routinely experience.

Bottom Line: You have two real choices. Both will affect how your tandem handles and, in both cases, what you'll find is that your tandem will steer more like a single bike -- being very precise and responsive to leaning inputs at speed but a little more of a handful as slow speeds and when climbing. The longer steering trail will also make the tandem twitch around more in response to your stoker's movements which would also take some getting used to. At first, this will feel really weird and perhaps uncomfortable given what you're used to with your Cannondale. However, after a few rides you should become comfortable with the new handling if you're used to riding racing bikes vs single bikes with touring geometry. Point of reference, our tandems have about 2.5" of steering trail -- both use Alpha Q forks.

Perhaps one of the best sources for your fork is Calfee Designs in Santa Cruz, CA. Calfee is the premier builder of composite tandems. They sell all of these fork models and Craig (as in Calfee) or Stella can also discuss the pros and cons of these forks relative to tandem use. http://www.calfeedesign.com/price_list.shtml

[thebearnz]

Looking for a similar answer for our 2005 Trek T2000.

I can't tell from Trek's website anymore what the pre-carbon Geometry was for the Crom-alloy fork. Thier new 2008 Carbon fork looks very "straight" compared to mine.

Anyone know if Trek have changed the Headtube angle? Or have they just changed the rake.

I notice the Alpha Q now only goes up to a 44 Rake.

Any suggestions for a tandem team approx 400lbs?

Biggest reason for looking at this is not for the weight loss - I have been told some good caliper brakes at the front will be better than the Shorti 6's as well as a little more comfort for the captain :)

Also just checking is the Fork length measurment you mention from the middle of the dropout to the top of the crown? (i.e where it touches the head tube?) if so the Trek T2000 Crom-alloy one is about 400mm. How much of an impact would the shorter forks have?

[Bill G]

We ran the Wound Up Carbon Fiber Fork on our 2002 model Cannondale Tandem that we had several years back with no problems, it worked great. The Tandem handeled fine and the ride was a lot better, I recommend it as we had no problems what so ever with the Wound up Carbon Fiber Fork and it looked great. The same fork works great on our Co-Motion Robusta as well, its a very solid Tandem specific fork.

Good Luck, :)
Bill G

[zonatandem]

16,000+ miles on our Alpha Q X-2 fork utilizing a D/A caliper brake on our Zona tandem; we are a tad below a combined team weight of 250 lbs. No issues, so far.
Asides from less weight, a c/f fork'll dampen some of the road vibes on your C'dale's front end.
Pedal on TWOgether!
Rudy and Kay/zonatandem

[sch]

Our new Co-Motion has the Alpha Q and a DA caliper brake. Brake works fine
but the nominal 25mm Michelin tire rated at 110psi pumped to 115 measures
27.6mm wide. It requires a moderate thump to get it out of the fork between
the fully released brakes and a forceful down shove to get it back in place.
Curious I measured several DF tires and found most to be within 1mm + to
0.5mm (-) in nominal width. So a 28mm might work but best be measured, as a tire much
wider than 28mm actual versus nominal is going to be a hassle to get in and out. As to the fork,
it is very positive in its handling, steering beautifully through high speed turns,
handling like a high end DF ought to handle. OTOH the combo of fork and
Rolf Vigor Tandem wheels with 240gm tire is squirrelly in no hands riding unlike
the beefier steel fork and heavier tire on the Burley.

[TandemGeek]

Anyone know if Trek have changed the Headtube angle? Or have they just changed the rake.

The changed the fork rake: steel = 55mm (Santana-like) and carbon = 50mm (Co-Motion-like)

For a 400lb team looking for calipers and comfort, consider the 1.125" Reynolds Ouzo Pro tandem fork with 55mm of rake. It won't change your handling but will provide everything else you're looking for in a very beefy package.

[lhbernhardt]

Regarding carbon forks with 1" steerers: We've got 2600 km to date on the Reynolds Ouzo Pro single-bike fork (all carbon including steerer tube) so far, no problems. Crew weight is 320 lbs (175-lb driver, 135-lb stoker, with a slight upward margin of tolerance for clothing and shoes.

Might sound scary, but just a few comments:
- People thought it was scary that we were using a 16-spoke Shamal on the front (this was before 16-spoke tandem wheels came out). After 10,000 km+, it's holding up just fine.
- The tandem never carries touring loads. We never even carry more than two bottles (it's got bosses for two cages, and living in the Pac Northwest, who needs more than one bottle each? Even on long supported rides, we have never gone thru one entire bottle between food stops).
- In order to easily remove the 23mm front wheel, it's necessary to use the Ultegra QR plus the Campag brake lever QR. Otherwise the tire will rub on the way out.
- I must admit that I think the Reynolds fork is a bit too "soft." On hard braking, it flexes a bit more than the carbon forks on my singles. But not to the point where I might feel concerned.
- I must also admit that I keep my fingers crossed on fast descents, so from a psychological standpoint, the security of knowing that you are on a "tandem-rated" fork may be worth the extra $300. Unfortunately, they don't make "tandem-rated" forks with 1" steerers, but I went with the Reynolds because I had it on very good authority that they could take the loads.
- I tend to be very easy on the equipment.
- The 4.5cm rake does affect the handling like TG said. It's a bit tricky standing on climbs, but I think it develops better tandem technique.
- I am now fastidious about checking for cracks before most rides.

- L.