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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 06-25-12, 09:28 PM   #1
PDub62
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Twitchy handling on a 2008 Santana Arriva with Carbon-V fork

We bought our first tandem, a size small steel Santana Arriva w/ carbon fork (700c wheels, S&S couplers), in 2008. Right away the handling felt a little twitchy to me especially at slow speeds but being new to tandeming I figured that was just how tandems handled. We've taken the bike on two trips where we pulled a BOB trailer and the trailer made the handling even worse. Last year we bought a 2011 Cannondale tandem and I have been amazed at how much better it handles; it is truly a night and day difference. One of the reasons we bought the Santana in the first place was due to all their hype about how much better their bikes handle but it doesn't seem to live up to that.

Has anyone else w/ a Santana noticed twitchy handling or is it just me?


I haven't done an in-depth comparison of the geometry of our Santana and the Double 'dale so I'm not sure if something like fork rake could be the difference. I suspect that the fork stiffness (stout aluminum tubing on the 'dale and carbon fiber on Santana) and frame stiffness (stout aluminum tubing on the 'dale and Niobium steel on the Santana) both must play a part.

Does anyone have any experience w/ changing the fork on a Santana from carbon fiber to steel or vice versa? I suspect the steel fork would be stiffer and may take out some of the twitchy-ness at slow speed but I'd like to have some anectdotal evidence that it would help before I drop $300 on a new fork.



Thanks for any feedback you might have!
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Old 06-25-12, 11:20 PM   #2
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Is the CF Santana fork original equipment? I'm wondering if the previous owner may have swapped out the fork for one with different geometry. We only owned one tandem, a daVinci, but I've never seen a posting that talked about twitchy Santana handling, usually just the opposite - very stable.
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Old 06-26-12, 05:16 AM   #3
PDub62
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Good question but the CF fork is original equipment; we bought the bike new and it came with that fork. It was a free 'upgrade' from Santana when we bought the bike.
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Old 06-26-12, 06:54 AM   #4
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First something quick and cheap to try. Wider tires will tend to slow down the handling vs narrow tires. Likewise less air pressure (within the normal safe range) will slow down handling at slow speeds vs high pressure. Basically more front tire rubber on the road will make it less twitchy.

For a better answer I need more information:


Tires used (especially the width)?
Tire pressure of front tire?
Do you use a handle bag? If so how much does it weigh when loaded?
Team weight?
Speed riding when unhappy with handling?
Is it more stable when riding at 18+ mph?
Does it track straight enough at 18+ mph to be tempted to ride with no hands?
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Old 06-26-12, 07:31 AM   #5
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Thanks for any feedback you might have!
Without meaning to be too bold, how tall you and your stoker and what's your combined weight?

What type of wheels are on the Santana?
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Old 06-26-12, 09:04 AM   #6
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1) Check the tires. What do you have on each bike? What PSI, and how old? Too soft of tires make the front end of a tandem feel insecure, and make it wallow and search. Too hard or just overinflated can make it feel twitchy by transmitting too many little bumps back. You need to adjust the PSI for how much you and your partner weigh. My favorites are Schwalbe Marathons.

2) Check your weight distribution. Try moving your weight forward or rearward on the bike (slide seats on their rails, adjust the handlebars). For me - bikes get twitchy when the weight is too far forward, and are searching and insecure when it is too far back.


Having a trailer make it worse makes it seem more like what I describe as wallowing - not twitchy. Normally trailers absorb little vibrations running through the frame - reducing twitch. At least with me they do - but everyone is different...


Can you swap the front wheels to see of the cannondale front wheel helps the Santana? I would suspect a loose steering stem or front axle problem before the forks...

Last edited by JustWant2Ride; 06-26-12 at 09:07 AM.
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Old 06-26-12, 02:41 PM   #7
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From my motorcycle days... if there is friction in the steering head bearings, it can make the steering feel unstable.

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Old 06-26-12, 03:05 PM   #8
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Answers to some of the questions above:

Tires used (especially the width)? Continental Gatorskin 700x28
Tire pressure of front tire? 90-100psi
What type of wheels are on the Santana? Velocity Fusion 36h w/ Hadley hubs. Stock from Santana.

Do you use a handle bag? Typically no but both times we used the trailer I also had a handlebar bag on.
If so how much does it weigh when loaded? 3-4 lbs

Team weight? Captain 155; Stoker 125; bike 43 lbs = 323 lbs
How tall are you and your stoker? 5'7" and 5'4"

Speed riding when unhappy with handling? Most noticeable at slow speed (under 10 mph)
Is it more stable when riding at 18+ mph? Yes
Does it track straight enough at 18+ mph to be tempted to ride with no hands? Not comfortably but I could probably do it. I can comfortably go handsfree on the Cannondale.

Can you swap the front wheels to see of the cannondale front wheel helps the Santana? I keep the Santana at my in-laws place a few hours away; I'll bring the 'dale front wheel next time I go and make the swap to see if it makes a difference.
I would suspect a loose steering stem or front axle problem before the forks: No, all seems to be in good mechanical condition (I'm a mechanical engineer and pretty anal about bike maintenance). Headset is also in good working condition; recently lubed and properly tightened.
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Old 06-26-12, 03:58 PM   #9
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Quote:
Originally Posted by PDub62 View Post
Answers to some of the questions above:

Tires used (especially the width)? Continental Gatorskin 700x28
Tire pressure of front tire? 90-100psi
What type of wheels are on the Santana? Velocity Fusion 36h w/ Hadley hubs. Stock from Santana.

Do you use a handle bag? Typically no but both times we used the trailer I also had a handlebar bag on.
If so how much does it weigh when loaded? 3-4 lbs

Team weight? Captain 155; Stoker 125; bike 43 lbs = 323 lbs
How tall are you and your stoker? 5'7" and 5'4"

Speed riding when unhappy with handling? Most noticeable at slow speed (under 10 mph)
Is it more stable when riding at 18+ mph? Yes
Does it track straight enough at 18+ mph to be tempted to ride with no hands? Not comfortably but I could probably do it. I can comfortably go handsfree on the Cannondale.

Can you swap the front wheels to see of the cannondale front wheel helps the Santana? I keep the Santana at my in-laws place a few hours away; I'll bring the 'dale front wheel next time I go and make the swap to see if it makes a difference.
I would suspect a loose steering stem or front axle problem before the forks: No, all seems to be in good mechanical condition (I'm a mechanical engineer and pretty anal about bike maintenance). Headset is also in good working condition; recently lubed and properly tightened.
Tire and pressure does not appear to be a problem to me although I would prefer a little more pressure.

You are not a heavy team so I doubt wheel, frame or fork flex is a problem unless they need adjustment or are damaged in some way.


Handle bar bag with 3-4 lbs will add to the problem especially if mounted high up on the handle bars. You say still a problem with no bag so I assume that is not the real problem.

On your fork rake issue: Generally low speed stability on Santanas is considered better than other tandem brands because they use forks with more rake (55mm) and less trail than most other modern brands. Some say this causes slow steering at higher speeds.

I would check the headset adjustment first. A loose or worn headset is a possibility. Worn headsets will feel twitchy at almost any speed however. Also check front wheel bearing adjustment just to be sure.

I am not sure of the fork rake on the Cannondale but I doubt it is as much as the Santana and most likely less. The Santana should have a 73 degree head tube angle and I do not know how that compares to the Cannondale.

This may be a case of you like some others just preferring the longer trail of the Cannondale. If that is the case and you want to change the Santana then a replacement fork could solve the issue. Chris King sells a head set that allows a 1 and 1/8 steerer fork to be used in place of the standard 1 and 1/4 inch diameter forks that are standard on Santanas. Not a cheap option but much cheaper than a new tandem. Before springing for a fork I would see if you can find out the head tube angle on the Cannondale as that also effects the situation.

Just for disclosure I will say that I had the opposite problem and prefer the lower trail Santana handling and actually use a replacement 1 and 1/8th headset to allow for a fork with more rake and less trail than the Santana.

Last edited by waynesulak; 06-26-12 at 04:06 PM.
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Old 06-26-12, 04:23 PM   #10
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Have you spoken to Santana about it?
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Old 06-26-12, 05:21 PM   #11
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This is the first time we've heard of 'twitchy' handling on a Santana.
Have put several thousand milles on Santanas and felt handling was a bit sluggish.
We are used to quick handling (but not twitchy) on our custom tandems in our over 37 years of riding as a duo.
Suggest inspecting headset and front wheel bearings.
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Old 06-26-12, 05:35 PM   #12
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I'm just going to take a WAG that the Santana geometry just doesn't suit your preferences for how a tandem should handle.

The Cannondale is a more laterally stiff tandem but I don't think that's a factor. The wheels / tires also sound like a wash.

The Cannondale also uses the same ~73 head tube angle as the Santana, but the Cannondale uses a 53mm raked fork spec. vs. Santana's 55mm raked fork spec. So, the Cannondale should have "a little" more steering trail. The slightly longer steering trail will provide a bit more steering feedback / a heavier feel at the handlebars at lower speed vs. the Santana using the standard OEM-spec 28mm tires that probably came on both tandems. This light touch on the Santana can feel "too light" to some captains and cause a captain to 'saw away' at the handlebars while trying to hold a tight line at slower speeds, but it also appeals to a lot of captains, particulary for uphill climbing stability. It also requires you to initiate and arrest turns at speed using a lot of handlebar inputs vs. the more intuitive leaning technique that a lot of captains feel comfortable with on single bikes. Again, there are also a lot of captains who prefer the Santana handling characteristic. I've found that I can adapt in just a couple rides, but still have a preference for the longer-trail bikes.

Without a lot of saddle time I find a Santana nearly impossible to track stand vs. our long-trail tandems where it's quite easy to do a standing stall for several seconds while waiting for a light change. Years ago we did a "how slow can you go" event where we did about a 40 second "rolling" trackstand on our Erickson on a nearly dead-flat driveway: would have been nice to have a slight angle. Tandemracer was the master and easily won the day on a Litespeed. I think I've mentioned before that you can easily understand how the different steering geometry affect the front wheel by trying to push and guide a Santana with your hand on the stoker's saddle vs. doing the same with a Co-Motion or other tandems that use less rake / more trail. The difference is quite pronounced.

Bottom Line, I don't believe there's anything "wrong" with the Santana, it's just not a good match... and, well: that happens. There are folks who find tandems at the other end of the handling spectrum -- short rake / long trail -- too "twitchy" as well. Funny how that word can mean different things to different folks.

It would be interesting to know if you've ever ridden a Co-Motion... with a steel fork or perhaps even a composite fork ... just to see how that felt to you.

FWIW, we started off on a Santana and moved on to something else after a year. The Santana was great but it definitely had a some low-speed and high-speed handling characteristics that didn't rock my world. Nothing that I couldn't adapt to, but just not spot-on to what I felt most comfortable with. Our triplet has Santana-like geometry and has those same handling idiosyncrasies... such that a different fork may be in our future. We'll see.

Anyway, that's just my .02. Good that you've found the C'dale to be a better "fit", so to speak.

Last edited by TandemGeek; 06-27-12 at 05:57 AM.
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Old 06-27-12, 06:15 AM   #13
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For reference I believe the following are rakes used by various companies that use a 73 degree head tube angle. Corrections are welcome:

Bilenky Steel 60.4 mm (slightly less if steeper HT angle used on tandem)

Santana Steel or Carbon 55 mm

Cannondale steel 53 mm

Comotion Steel Fork 50 mm (Comotion also uses various carbon forks below)

Wound up Carbon Forks available 43-50mm

Various carbon fork manufacturers usually 43mm - 45mm. These are used by various tandem makers that do not manufacturer there own carbon forks. These are the same rakes as used on most single bikes.
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Old 06-27-12, 06:34 AM   #14
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Corrections are welcome
It's close enough...

The head tube angles on some of the small size and very large size tandems are sometimes tweaked a bit and Bilenky goes as far as tweaking the fork rake on it's smallest size frame.
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Old 06-27-12, 10:22 AM   #15
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twitchy handling sit CF fork

I agree that the head-set would be a good place to start looking. We bought a new co-motion mocha in 2007. In an effort to save money (I guess) the dealer installed what looked like thin walled electical conduit, hack-sawed to length, to make up a 2.5 inch spacer. Last month, before selling the bike, I bought a set of proper spacers and the handling really tightend up. A really big change in low speed handling from what seemed like a very small modification. On inspection, the dealer's home-made spacer was deformed as a result of loading.

Good luck sorting this one out.
Joe
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Old 06-27-12, 11:05 AM   #16
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The bars and stem can have a significant effect on steering.
I'm new to tandems and am more of a mountain biker (I do have a touring road bike though) so I'm speaking more in general terms. But a longer stem, longer reach on the bars, and wider bars, will all help to slow the steering.
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