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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 05-12-13, 12:31 PM   #1
bivinco
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New Ti custom tandem build with max 25 pounds (Shimano Di2/Gates/Hydro Disc)

Dear Bike Forum community
one year ago I build up my first alloy tandem with drop bar, double chain ring with 50/34 and disc brake. It goes very well and soon I want to make an order for a Ti custom tandem. Besides the knowledge around and inspired by some very nice builds here in the forum I would like to share with you my full process from A to Z.

I am from Europe, years ago I cycled a lot (15k km/y). But since I started my own business 4 years ago my priorities has shifted and kilometers/year almost below 2k . Due to time limitation tandem cycling is perfect to use my limited time with my wife on what we like. And now it is time to re-prioritize life.

Goal: Very light (less then 11.5kg= 25.3pounds w/o pedals) , stiff, comfortable and cool looking tandem.

Must use components:
- Custom Ti tandem frame
- Shimano Dura-Ace Di2 7900 with (hydro)-Disc
- Drivetrain: Gates Carbon drive and chain with double chainring 50/34 (or in alternative 53/39) and 11/28 cassette

Captain: 75kg
Stoker: 55kg
Maximum additional weight: 15kg

I don't know if if you want to hear my story. But I realized the tandem community here in Europe is much smaller then in US and I would be more then happy to learn from you. What do you think?

I will start to share with you
- geometry
- frame drawing
- part list
and more...
and finally within 6 month the result
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Old 05-12-13, 10:28 PM   #2
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bivinco,

we would be very interested to follow your progress and provide our thoughts/opinions any questions/concerns that you have.

yours,

Capt'n Haddock
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Old 05-13-13, 12:18 AM   #3
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Well, I'll want to hear all about this!

I don't know how much Ti frames weigh. Finding frame weights isn't particularly easy.

To do this project, a spreadsheet is a must. The spreadsheet for my tandem is on Google docs here. I've included on here a link to source each component.

PM me, and I'll email you my Excel file, which might be more useful.


Edit:

I've put the Excel spreadsheet at Dropbox here to download.
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Last edited by Ritterview; 05-13-13 at 09:48 AM.
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Old 10-13-15, 03:53 AM   #4
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Dear all,
it took me so long but my project is finally coming to an end. I will share all details in the next weeks.

A custom Ti frame was build based on my requirement. The concepts of all assembling parts was the most difficult decision and certainly influenced strongly the frame build. The waiting time for the Ti frame certainly delayed the project too.

Low weight and stiffness were my priorities.

As a teaser:
- 28 inch tandem frame and wheels
- using 2015 XTR brake and shift
- with Shimano Ultegra Tandem cranks (FC-R601/603) combined with Gates carbon drive belt on non drive side and XX1 cassette.
- 142x12 and 12x15 thrue axle rear and front
- White Industry hubs with 36h f/r
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Old 10-13-15, 05:32 PM   #5
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Do not think it will be possible to do a 25 lbs build with ti-frame and components you mention (even without pedals).
Hope you will not not disappointed and that I am wrong . . .
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Old 10-14-15, 01:15 AM   #6
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Quote:
Originally Posted by zonatandem View Post
Do not think it will be possible to do a 25 lbs build with ti-frame and components you mention (even without pedals).
Hope you will not not disappointed and that I am wrong . . .
Zonatandem is right. I exceeded my weight goal of 25pounds but the specification from the beginning changed a lot too. No dropbar handlebar anymore. After having finalized my project I am pretty sure I could have reached 25 Pounds with some more budget for more carbon parts and wheels and the just newly showed CX1 with 10-42 cassette. The tandem has now a final weight of 13.4kg = 29.5 Pounds (w/o pedals) but travel ready with rear carrier. Also there are still tons of options to reduce the weight by around 3 Pounds with lighter saddles, rims, seatposts, thrue axle QRs (f(r), rear carbon handlebar, no inner tube (tubeless), lighter stem, etc,

The custom Titanium frame weight is 3.5kg (7.7 Pounds) with oversized tubings, ZS44 headtube, 142x12 thrue axle in the rear.

I will share with you first the frame drawing. Later the parts specification list and at the end some pics.
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Last edited by bivinco; 10-14-15 at 01:28 AM.
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Old 10-14-15, 08:51 AM   #7
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Your initial plan was for a custom road tandem (eg. Dura Ace Di2), but it has changed to a 29" mtb tandem with front suspension fork. the fork seems to be a double-crown fork.

If so, I'm curious about your design choices. First, why use Ti instead of carbon? Carbon will probably be lighter (for same stiffness) and can offer more flexible frame geometry. Also, a carbon frame won't need a lateral tube. Will the front water bottle be easily accessible with the front lateral?

If low weight is important, why not use the Lightning carbon cranks instead of the Shimano 601/603 cranks?

Your choice of components (wheels, bars, etc) will depend if this tandem is for rolling XC terrain or more technical singletrack.
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Old 10-14-15, 09:37 AM   #8
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Originally Posted by mtseymour View Post
Your initial plan was for a custom road tandem (eg. Dura Ace Di2), but it has changed to a 29" mtb tandem with front suspension fork. the fork seems to be a double-crown fork.

If so, I'm curious about your design choices. First, why use Ti instead of carbon? Carbon will probably be lighter (for same stiffness) and can offer more flexible frame geometry. Also, a carbon frame won't need a lateral tube. Will the front water bottle be easily accessible with the front lateral?

If low weight is important, why not use the Lightning carbon cranks instead of the Shimano 601/603 cranks?

Your choice of components (wheels, bars, etc) will depend if this tandem is for rolling XC terrain or more technical singletrack.
The frame can handle tyres up to 55-622 (28 x 2.15) and is optimized for the Whisky No.9 carbon fork. We don't want to go with a suspension fork. Our first idea was to go with an Enve Road Disc but then Enve Cross Disc. But due to availability we went for the Whisky fork. Ti was my choice of material because of longevity and crash security. Also we fly a few times a year and I rather prefer metal compared to Carbon. At the end the weight difference is not too much between both frames materials. In terms of performance carbon would be better but Ti gives us many other advantages and I just love the look, touch and feel of Ti. To take out the front water bottle is no problem.

Last edited by bivinco; 10-14-15 at 09:50 AM.
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Old 10-14-15, 12:56 PM   #9
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Quote:
Originally Posted by mtseymour View Post
Your initial plan was for a custom road tandem (eg. Dura Ace Di2), but it has changed to a 29" mtb tandem with front suspension fork. the fork seems to be a double-crown fork.

If so, I'm curious about your design choices. First, why use Ti instead of carbon? Carbon will probably be lighter (for same stiffness) and can offer more flexible frame geometry. Also, a carbon frame won't need a lateral tube. Will the front water bottle be easily accessible with the front lateral?

If low weight is important, why not use the Lightning carbon cranks instead of the Shimano 601/603 cranks?

Your choice of components (wheels, bars, etc) will depend if this tandem is for rolling XC terrain or more technical singletrack.
Yes, there are still options to lower further down the weight. Here my priority was on reliability. My first choice was the FSA SL-K LIGHT TANDEM crank but availability in Europe is zero. We tried to get from Italian based European distributor but even they dont have any stock. Therefore we opted for good Shimano parts.

We will use the bike only on gravel and paved roads. No mountainbiking.

Btw in front we use a BSA 68mm shell BB with Exzentriker II.
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Old 10-14-15, 04:21 PM   #10
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Quote:
Originally Posted by bivinco View Post
We will use the bike only on gravel and paved roads. No mountainbiking.
When you say 55-622 tire clearance, do you mean 700C tires that are up to 55mm wide? Compass makes 700c x 35mm and 700C x 38mm tires that will work well for gravel and paved road.

Depending on how much riding is done on gravel roads, the XTR Di2 gearing may be too low. With 36-26 rings and a 11-40 cassette, your low gear is 18.2 gear inches, while your top gear is only 91.6 inches. On the road, you will spin out often.

We use the Ultegra 6870 Di2 with 50-34 and 11-28 cassette and find the gearing is low enough for road use. We climbed the steepest road that we could find (10-12%) before we made the switch from a triple crank (52-39-30) to a compact (50-34). If you use a 50-34 with a 11-40 cassette, you should be able to climb virtually any gravel road. Did you test the gearing for the terrain that you will ride?
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Old 10-19-15, 11:15 PM   #11
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Our custom full carbon fiber road tandem, built on 2003, weighed in at 26.5 lbs.
It now has 45,000+ miles on it.
Pedal on TWOgether!
Rudy and Kay/zonatandem
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File Type: jpg picasabackground.jpg (56.8 KB, 18 views)
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Old 10-22-15, 05:24 AM   #12
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Finally I got some nice pics
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File Type: jpg Titan_Mass_Tandem_XTR_1.jpg (89.3 KB, 49 views)
File Type: jpg Titan_Mass_Tandem_XTR_2.jpg (85.8 KB, 35 views)

Last edited by bivinco; 10-22-15 at 05:29 AM.
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Old 10-22-15, 05:29 AM   #13
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Quote:
Originally Posted by mtseymour View Post
When you say 55-622 tire clearance, do you mean 700C tires that are up to 55mm wide? Compass makes 700c x 35mm and 700C x 38mm tires that will work well for gravel and paved road.

Depending on how much riding is done on gravel roads, the XTR Di2 gearing may be too low. With 36-26 rings and a 11-40 cassette, your low gear is 18.2 gear inches, while your top gear is only 91.6 inches. On the road, you will spin out often.

We use the Ultegra 6870 Di2 with 50-34 and 11-28 cassette and find the gearing is low enough for road use. We climbed the steepest road that we could find (10-12%) before we made the switch from a triple crank (52-39-30) to a compact (50-34). If you use a 50-34 with a 11-40 cassette, you should be able to climb virtually any gravel road. Did you test the gearing for the terrain that you will ride?
Yes, we use 28'' wheels with a Schwalbe Supreme tyre. Gravel is less but as long as it is not wet/muddy the tyre doing fine. Using it already now.

On the pic is still the 11-40 cassette mounted but in the meantime we use the XX1 cassette and it is doing very good up and down.

Because of the already purchased Gates Carbon drive parts (left side) we didn't want to want change again to a compact crank (different bolt circle 110mm vs. 130mm). On my winter road tandem we are using 50/34 with 11-32 cassette. Works fine.

Last edited by bivinco; 10-22-15 at 08:27 AM.
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Old 10-22-15, 06:21 AM   #14
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Find below my Excel parts listing for download. As mentioned the frame is a custom frame done on measure and based on Retul measurement by a Swiss maker. I mentioned it in the Excel list.
I think this project is still not finished for me and there is still some potential but first I need to enjoy cycling on this beauty and save some more money

https://www.dropbox.com/s/pskekov2oi...Teile.xls?dl=0
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Old 10-22-15, 08:26 AM   #15
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Your frame is beautiful! It`s my first exposure to Hilite Titan but they obviously do excellent work and were able to customize your design.

We`re fortunate that a local custom builder, DeKerf Cycle, was able to make a custom ti stoker stem for our Calfee Tetra. It`s the right length and rise and works better than our previous stock stem.
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Old 10-22-15, 08:56 AM   #16
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Yes, stoker stem is perfect in angle and length and so light Since we gave our Retul values to the builder they designed a 2D version of the bike within BikeCAD. Every value was matched to the millimeter. The final accuracy was astonishing. Also I am impressed by the frame welds and overall quality. I looked at different welders and suppliers and traveld to NAHBS last year to talk to Kent Eriksen. But finally we opted for a HILITE titanium because of there flexibility regarding my wishes.
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Old 10-22-15, 01:32 PM   #17
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Originally Posted by Ritterview View Post
Well, I'll want to hear all about this!

I don't know how much Ti frames weigh. Finding frame weights isn't particularly easy.

To do this project, a spreadsheet is a must. The spreadsheet for my tandem is on Google docs here. I've included on here a link to source each component.

PM me, and I'll email you my Excel file, which might be more useful.

Edit: I've put the Excel spreadsheet at Dropbox here to download.
Ritterview; You must really like your tandem. I have actually never heard of anyone spending that much to put one together. Enjoy!!
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Old 10-22-15, 03:55 PM   #18
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Ritterview; You must really like your tandem. I have actually never heard of anyone spending that much to put one together. Enjoy!!

I think there are much more insane and nonsense hobbies then investing into a bike. Just imagine collection old cars... Also I don't see the issue. Many high end single bikes are more then 10k and an tandem is for 2 and even custom.
everybody has different level for that and my new tandem was also in a high price range. This was the reason I didn't fill out the according column. YOLO
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Old 10-22-15, 04:05 PM   #19
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I want to share one nice detail which finally worked out well. Since I use on the left side a Gates Carbon drive belt I must have a fixed boom tube length. Production was very accurate. To tighten the belt most companies using standard eccentric bb which works well but heavy and ugly. I opted for a standard 68mm bb and using a very small eccentric bb from a German maker with skf bearings. The bb gives +/-5 mm eccentric moment which was enough to have the needed tension. Finally I only needed the eccentric bb in the front.
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Old 10-23-15, 12:42 AM   #20
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I opted for a standard 68mm bb and using a very small eccentric bb from a German maker with skf bearings. The bb gives +/-5 mm eccentric moment which was enough to have the needed tension.
This is an unusual and tight-tolerance alternative to the standard eccentric. I gather that it only uses the Hollowtech spindle. Please post a photo or drawing without the crankset.
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Old 10-23-15, 08:31 AM   #21
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This is an unusual and tight-tolerance alternative to the standard eccentric. I gather that it only uses the Hollowtech spindle. Please post a photo or drawing without the crankset.
@mtseymour. I didn't want to be usual Sorry, difficult for me to take the crank off. I will do pics with the next service. For the time I am happy that is properly assembled. Yes, using Hollowtech cranks.

I have in the front and back standard BSA bottom bracket with 68mm. Gates requirement for using Gates belt with 69 sprockets is:
DIM A (69T SPROCKETS); NOMINAL CENTER TO CENTER DISTANCE 720.69MM (712.69MM FOR BELT INSTALLATION, 722.69MM FOR PROPER BELT TENSIONING.

The boom tube length was set to the proper tensioning length of 722.7mm. I was told by builder they can work it as accurate as less then 1mm. The belt extension over time is very very little and the eccentric bottom bracket should handle this. Time will tell but I am confident.

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File Type: jpg IMG_2374.jpg (83.4 KB, 18 views)

Last edited by bivinco; 10-23-15 at 08:38 AM.
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Old 10-23-15, 09:04 AM   #22
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I think tandems are inherently unusual

We also use the Gates belt drive so we're familiar with the setup. Is there a bolt on the bottom of the front BB shell to loosen the eccentric? How do you rotate the eccentric to increase or reduce the belt tension?
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