The process was certainly educational for me. There are a lot of considerations when designing a tandem that you don't need to worry about on a solo frame. Like trying to fit a 75" captain on the same bike as a 65" stoker. Thanks to Mark's excellent guidance, we ended up with a great looking frame. I had a few requirements:
- Similar geometry up front to my 64cm Habanero
- Support for disc brakes on the frame
- As many water bottle braze-ons as possible
- Ability to fit 700x35 tires
- Priced around $5,000
- Pump peg
Mark just about hit the $5K mark on the nose. This strikes me as remarkable for a custom titanium tandem with solid components. When I looked around at other Titanium options it was tough to get anywhere near $10K.
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| Ready For Disk Brakes |
Mark got the frame a couple months ago, and started assembling the bike. He did discover a problem right away; the rear brake bridge was a little too low to clear the tires we planned to use. We could have just gone with smaller tires, but I've really become a fan of larger tires, so I wanted to keep the option of using 700x35s.
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| Panaracer 700x35 |
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| Mark's brake bridge mod provides clearance for 700x35s. |
Delivery And Assembly
Mark generously offered to meet me in St. George where I was crewing for Hoodoo. Ultimately though I gave up on the logistics of that and he shipped it to me in Oregon instead.
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| Exciting! |
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| Ready To Ride! |
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| One of these dropouts is no longer like the other |
The rest of the assembly went uneventfully. It's really only a 15 minute process or so to unpack and assemble a well packed bike. I was a little nervous about the carbon fiber fork, but ours is a tandem-specific Wound-Up, and it feels really beefy. Likewise I had Mark go with stout wheels, Velocity Dyad with 36H in front and 40H in back.
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| Wound-Up tandem fork |
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| Still need pedals and another seat.. |
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| Poor-Man's Tandem Workstand |
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| Official Weigh-in: 37 pounds, 15 ounces. |
Test-Ride
With our trip to the San Juan Islands just a few days away, we needed to get a test-ride in. Neither I nor A__ have ever ridden a tandem. So really had no idea what to expect. I read a few tips online and then we loaded the bike in the truck and drove to a nearby school with a big parking lot and endless miles of low-traffic roads nearby.
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| 75% of the HBC Titanium Fleet Represented Here. |
After a short 5 mile loop we started to feel more comfortable. A few small downhills where we hit maybe 30MPH and a few tiny climbs passed uneventfully.
Riding Impressions
We've got about 50 miles on the tandem now, comprised of ~15 mile rides. Some of the early challenges revolved around cadence. A__ tends to apply power to the pedals for fewer radians than I but, at least on flats, we're now more synchronized there. Riding solo I have a cadence in the high 70s, which exaggerates the problem above. Switching to a higher cadence helped even out our pedaling, but when climbing even small hills we still get a bit out of sync.
After getting the wrinkles figured out, it's been quite enjoyable riding the tandem. On flats we cruise at about 19-20MPH, about the same as I'll do on a solo ride. Climbing is considerably slower, and we're not descending especially fast, so overall average is perhaps 17MPH. Faster than A__ alone, and slower than me alone, but that will get better with practice.
I really have nothing against which to compare the Habanero, but my impressions so far are positive. We did have an interesting experience with cross-winds on San Juan Island; a tandem has a larger area and a longer moment-arm than a solo so even a moderate breeze really made us wobble. I'm sure this will get better with practice, but I'd hate to imagine riding a tandem in a strong wind.
Component Thoughts
The triple chainring is well out of sight of the captain. Coupled with the additional abstraction from the drivetrain, it's tough to tell which ring you're in without peeking under your arm or asking the stoker. A tandem seems like an ideal application for a Shimano flight-deck, or better yet XTR Di2 synchro-shift.
I really hate v-brakes. They stop the bike just fine, but opening them up to take out a wheel is a real pain in the neck. The front brake has a little jagwire adjuster that helps a bit, but I've not yet succeeded in getting the back brake open.
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| Trying to get those brakes open is a real pain |
I've ordered a set of Paul MiniMoto brakes which allegedly have a better quick-release mechanism. If I'm happy with those I'll probably order a couple more sets, for the fixie (which currently has V-brakes) and the rando habanero (which has cantis).
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| Paul MiniMoto quick release |
7 comments:
Pretty bike! How on earth does one fly with a tandem? I would think that, even on the other side, it would be near impossible to transport via normal rental car.
Yes, traveling with a tandem is a chore. There are lots of options with couplers, but that introduces a whole new level of complexity.
For a rental car a 7-foot long roof probably suffices. It's tough (and expensive) to find a tandem rack; I'm curious to try my seasucker rack as an inexpensive option.
I see my comment from my iPhone Blogger app did not take. Note to self to add a negative review of that app next time I find myself watching bananas ripen.
This looks unspeakably awesome. As Damon notes, it is just pretty. And as I've noted, pretty is about 50%, maybe more, of the battle.
Dropouts: steel, I hope? If aluminum it makes me more nervous, although a single episode of bending seems unlikely to matter.
My bet is on cable length for shifting frustrations more than groupset. I have no complaints about the 105 set on my Neuvation, when newly tuned. And I've been developing a theory that frame flex hurts shifting where the cable stops are on either side of the flex point. Titanium is famously subject to flexion and no question there will be motion between your cable stops, so tension simply can't be consistent. I actually wonder if you could induce a shift with substantial enough turning, cranking, or both at once.
I hope this works out for you so I can justify the breakaway tandem next year. On the other hand, not sure my marriage could take it.
A thought on the fork -- why not contact the manufacturer? They are inclined to be very cautious, so at least a "do not worry" can rule out concerns. A "worry" response may not get you far, but it may be a basis to see if UPS will make good. (They won't, I'm betting.)
OK, one last. I see this pitch on the Habcycles website:
"45% lighter than 4130 steel yet 2% higher strength to weight results in a lighter yet stronger frame."
If 45% lighter but 2% higher s-t-w, why is not a titanium bike substantially _less strong_ than a steel bike? I would think you'd want ~2x S-T-W to be willing to take the titanium.
Unless steel is simply overstrong for the purpose.
Just a thought.
It looks like Sheldon Brown agreed with that:
Excerpting from http://www.sheldonbrown.com/frame-materials.html#titanium
Steel vs Titanium
Look at the chart again. You'll see that identical steel vs titanium frames would be about equal in strength, but that the titanium frame would be about half the weight and half the stiffness.
Such a frame would likely have a whippy feel due to the reduced stiffness, especially in loaded touring applications. To compensate, builders of titanium frames use somewhat larger diameter tubes to bring the stiffness more into line with what riders like. This tends to increase the weight a bit, but by making the walls of the larger tubes a bit thinner, they can compensate to some extent, and come up with a frame that is still lighter than a normal steel frame.
I believe the fork dropouts are aluminum.. Your suggestion to contact Wound-up is a fine one. I'll send them the picture of the bent dropout, and my ghetto straightening job.
I'm fairly certain you're right about the cable length being the main issue with shifting. I know on your cannondale it has always been possible to induce ghost shifting by standing and cranking on a steep hill. A tandem will certainly have some frame flex. Maybe the solution is to give the shifters to the stoker!
This seems to be a better description of titanium:
http://www.strongframes.com/more/metatllurgy-seven-part-series/the-titanium-advantage/
This implies that what Habanero describes as "strength" is actually "stiffness".
"Our second property is stiffness, or Young’s modulus (E). The titanium that you find used in a majority of bicycle frames has an E of around 15 million pounds per square inch – approximately half that of steel. This means that steel and titanium are roughly comparable when it comes to the stiffness-to-weight ratio."
You often hear Ti bikes described as "whippy", and this is probably why. Regarding "strength":
"The tensile strength of titanium is also excellent. The cold-worked-stress-relieved yield strength ... of the 3/2.5 alloy ... is typically 100-130 KSI or more. This compares favorably with many steels we find in bicycles. Remember, too, this is achieved with fantastic elongation numbers, and at almost half the weight. And we haven’t even talked about fracture toughness and endurance limit yet.
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The fatigue strength is another property where titanium performs beautifully ... As long as these loads are kept below a certain level, titanium and steel both have thresholds below which they will never fail. Almost none of the aluminum (including the metal matrix composites), magnesium and beryllium used in bicycle fabrication has a defined endurance limit, so you need to design around it, as was explained last time."
I wonder if a tandem bike can plane... I'm sure JH would know...
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