See how I assemble a titanium tandem bike

The author of this article is Mr Alex which is the customer in our side. He explained how he conceived and assembled a titanium tandem bike. The titanium tandem bike frame was designed and produced by XACD Titanium cycles. I hope to give you some enlightenment for preparing the component tandem bike.

You like to cycle, you cycle a lot and you cycle with your loved one.

Lovely through the Limburg hill country with an occasional climb and of course also beautiful departments.

This is all fine on your own bike as long as there are no restrictions. But what now if your loved one has Diabetes, a heart condition or another (minor) physical or has a mental disability?

Then “each on his own bike” has its limitations. And so it was in my case.

My beloved could no longer (continuously) muster the power I push into the pedals. And if you would like to continue cycling together, for your necessary exercise, relaxation or just for fun, then there must be a solution. That's how I thought about one years ago that the problem outlined above could be solved by. . .a tandem!

Now I'm someone who can't stand it when you're somewhere “in the middle of no-where” condition and your cycling equipment breaks down. Chain over, derailleur jammed, shift mechanics that no longer work. . . . you know it. And so?

There had to be a decent, preferably maintenance-free, trouble-free tandem.

After a lot of searching on the internet I found out that what I wanted was actually not available. At least, not if you don't want to take out a second mortgage on your house. In short: I decided to build a tandem myself. Here's a short lecture about the how and why.

First of all, the specifications:

Frame: Titanium, 3AL2.5, Handmade by XACD titanium cycles

Frame weight: 4.8 kg

Frame geometry: Pilot 60cm.-Stoker 49cm.

Frame wheelbase: 186 cm.

Fork: Titanium bike fork, 3AL2.5, Tapered, Thru-axle design, Handmade by XACD titanium cycles

Stem: Titanium bike stem, 3AL2.5, 60mm / 31.8mm, Handmade by XACD titanium cycles

Wheels: 27.5 inch, 36x Sapim Race spokes, DT-swiss H522 disc

Rims: 35mm wide

Front hub: Hope, Pro-4, 110x15 (Boost)

Rear Hub: Rohloff, 500/14T speed hub

Front thru axle: KCNC, modified 110x15mm. 135mm long, 1.5mm pitch

Rear thru axle: DT-swiss, 9mm x 135mm QR, Titanium

Brake discs: Mi-xim, 203mm, 6 bolt, RED “ice technology”

Brakes: Shimano, XT (BL-T8100)

Eccentric axle front: Bushnell eccentric by Problem Solvers

Axle pilot/stoker: Shimano, BB-UN300 (68mm x 110 solid, square mount)

Crank front: Thorn, tandem crank, 175mm arms

Crank rear: Thorn, tandem crank 170mm arms

sync. Pilot/stoker: Gates Carbon Belt, 174T, 2x chainring 104mm, 4bolt mount, 42T

Drive train: Gates Carbon Belt, 113T, chainring front: 104mm, 4bolt mount, 46T

chainring back: Rohloff 19T, spline mount

Pilot handlebar: Toseek, 31.8/680mm straight, Carbon (3k)

Stoker handlebar: Toseek, 31.8/680mm riser, Carbon (3k)

Pilot seat post: Titanium, 3AL2.5, 31.6mm-350mm long, Handmade by XACD

Stoker seat post: Toseek , 31.6mm-350mm Carbon(3k)

Pilot saddle:ISM,PR2.0 Performance saddle

Stoker saddle: Selle SMP, TRK-gel-Lady

Handlebar grips: Ergon GP1, Front: large, for Rohloff. Rear: small, normal version

Pedals: Shimano, SPD PDM324

Tandem total weight: 19.8 kg.

And what does it all look like then?

Well so. And from the other side:

Now, after seeing the result, a number of questions may have arisen about why a particular component or structure has been chosen. I will try to admit the most prosperous things lights.

The frame:

I chose a Titanium tandem frame because it offers a number of advantages compared to aluminum, steel or even carbon. I wanted a frame that is durable, has good handling characteristics and absolutely robust at a not too high weight. The latter because we also want to be able to do the tandem take with the car. With those requirements you actually quickly end up with Titanium. Aluminum and steel suffer from metal fatigue over a longer period of time during extreme use. Moreover there should be a lot of paint on those frames to protect them from the elements. OK. I hear now people say you can anodize aluminum and choose stainless steel for steel. Correct, but that doesn't take away the other limitations or features. Carbon is too much for me fragile and also too stiff so that it fell off immediately. So it had to be Titanium.

Then the measurements.

I have chosen to design the tandem in a 27.5 inch wheel version.

The reason for this is that this is somewhere between extremely strong 26 inch wheels and wonderfully rolling 29 inch wheels. Well, and I couldn't really change the geometry much if you consider that I am 1.95 m. and my beloved but just 1.68m, also the XACD give me much more good suggestions, I am very greatful.

The wheels :

As mentioned, 27.5 inch wheels have been chosen. I decided to go for really wide rims (35mm.) with wide tires so there is enough air to dampen the ride and still work smoothly through the to roll terrain. And all without the need for suspension in the form of a spring front fork or rear bridge.

The drive:

In a tandem, there must be a gap between the person in front (pilot) and the person at the back (stoker). synchronization of the drive. It was immediately clear from the start that this was a belt was going to be because I didn't feel like trouser legs between the chain, grease on the legs and more that kind of inconvenience. And because over the years I have enjoyed the great concept with my other bike. I have come to really appreciate belt drive, only had a belt drive on this tandem come.

And if you then opt for belt drive, the gear issue is actually limited to 2Choices: 

Either a Rohlof 500/14 gear hub OR a Pinion P1.18 gear box. To with those last to start: You have to somehow match the power of the pilot with the stoker. This can be done with a connection on the left as in this tandem or with a connection on the right. In both cases, a blade has to be mounted on the gearbox and that is not yet possible with Pinion to get. You could then stand behind the milling machine and make something, but I don't have that chosen for. I had found someone who had already thought of that as a prototype but decided anyway to go for the solution based on a Rohloff hub. Not least because of the a substantial difference in price.

Now I hear people shouting that Shimano now also has gear hubs but they are, so turns out, not able to withstand the forces that are put into the system in a tandem.

The final assembly:

After the frame and the drive, there is little left than the final assembly such as brakes, steering, saddles, seat posts, bottom brackets and some loose parts that are useful.

The most important thing in that story is undoubtedly the brakes. I chose Shimano XT brakes with 203mm. Brake discs. During our exploration phase we have several tandems ridden and what always stood out was the moderate braking capacity. Because over the years I have, I have come to appreciate the quality ratio of Shimano XT brakes (as far as I am concerned DE standard for every quality bike) they should also be mounted on this tandem to become. And because I've already had 140mm brake discs on a descent that melted (literally!) I decided to go for "extremely sure" and chose 203mm brake discs.

The axles I used for the cranks are very normal, solid, Shimano UN-bb300

axles as they have been used for years in just about all city and commuter bicycles from Hollandse brokerage. Slightly heavier but virtually maintenance-free and almost impossible to break. And the best

everything ? For less than a tenner each!

The seat post at the front is made of titanium because that's where the handlebars for the stoker get stuck, so you have to have something. The stoker's seat post is made of Carbon just like the handlebars. Just because you can get it cheap through AliExpress, right?

The mounted saddles are a result of years of experience with cycling. For me an ISM PRO2 saddle and for my beloved a wide Seller SMP ladies saddle. Hours of cycling pleasure without pain to you ass!

Last but not least, maybe I should tell you something about the production process and the put together scraping the parts for this tandem project. I had the frame welded together in China by XACD. I've had those ladies and gentlemen before Had the titanium frame welded together and I was very satisfied with how that went, what the quality was and the very competitive price that had to be paid for it. As far as I can I couldn't get it cheaper here in the Netherlands or Europe. I must confess that I am left with an uneasy feeling that I too am moving to China for my things.

If I had this frame in the same quality and at the same price (slightly more expensive it would be acceptable) I certainly would have done that. Unfortunately, the facts are different. Oh, before I forget: CORONA.

Man, man, man, what an impact that has had, and still getting married, on scraping together of the necessary parts for this bicycle. Everyone went cycling in the corona time (well, what you had to do a lot differently) with the result that a great scarcity has arisen in even the most banal components. I was in contact with various suppliers and they all complain rock and bone. I have on some parts have to wait more than 4 months And then there is also something like Brexit (the cranks came from England) and of course the import levies of tax. Not all to make you very happy. A (maybe something immoral) tip in this: Make sure the value of the goods on the packing slip is as low as is possible. You can e.g. It is best to make good agreements with the people in China. . .

Closing.

It took almost a year from "idea" to actually together on these tandem bikes with my beloved. The first impressions are very positive. It rides very comfortably and easily.

In fact, braking is so good that you almost have to be careful not to squeeze the handle too hard. It ease with which you get up to speed, especially due to the smooth shifting of the Rohloff hub, is real an experience. The handling on this tandem feels good but to really be able to say something about it, I will have to do a lot of miles first. And that will certainly happen because after the rain. In recent times the weather forecasts are good and so many km have to be made be. CYCLING!

A sporty bike regards,

By Alexander