'New' Tandem owner - advice please (wheels, forks, cranks)

craker

'Aint she a beaut ;-) ?

Rescued from ebay this weekend we have a lovely 20kg Gitane tandem of unknown provenance.

Now I'm not pretending it's worth spending silly (any?) money on, I'm a newbie with tandems so if you could offer constructive advice I'd be grateful..

Mechanically the thing is in much better condition than it looks. All the threads and bolt heads seem OK, chain doesn't look like it's had much wear.

The wheels I believe are originals, they've got fantastically wide rims and weigh a fair bit. Any reason why I can't stick old MTB wheels on? The narrower rims would work better with some Schwalbe City Jets I've got hanging around. Of course I haven't worked out what to do with the 126mm spacing / six speed freewheel issue.

Next is the forks, which judder back and forth alarmingly under moderate braking. Should I try to replace them, would I have to look at Tandem specific forks?

Finally the cranks. I want shorter cranks so my 9 yo daughter can pedal, however the timing gear is attached to one side. Where do you get cranks with attached timing gears from? I haven't counted the teeth, 32 at a guess. Other options are drill and tapping new pedal locations in the crank arm or do a cut and shut job with an angle grinder and a friendly welder.

Thanks!

andy_wrx

Tandem wheels are (should be !) built stronger than usual to cope with the extra weight - 48 spoke is normal.
However, modern MTB wheels are probably stronger than wheels were 20 years ago
So if they fit, no reason why not

Similarly tandem forks are normally beefier to handle the extra weight.
Front-end geometry is usually a bit slacker than on a solo as the extra weight makes the steering heavy otherwise.
Now whether this is done on your frame by the headtube angle or the fork rake...measure it and see.

Kiddiecranks are often fitted to tandems with a child on the back, can be adjusted as she grows
http://www.sjscycles.co.uk/kiddy-crank-seat-tube-attachment-block-with-1225-mm-sealed-b-b-bearing-286-318-mm-black-prod18903/

See the contact details for SJS on that link - they make Thorn tandems and might be worth a phonecall for help/advice

woolwich

I assume the wheels on it are 26" at present? If not, fitting 26" MTB wheels will alter the steering geometry. Otherwise nothing wrong with 26" wheels for Tandems. They are preferred by some manufacturers due to high strength from the smaller diameter, Thorn only make 26" wheel tandems.
However I would be reluctant to set about changing the wheels simply because they are heavy and you want narrower tyres. You will never be accelerating the bike quickly anyway so the weight is no disadvantage. Also high volume tyres are an absolute benefit on most tandems due to comfort.
The stoker can have a rough time on a tandem. Look at the design of the frame. the captain sits more or less in the mid point between the wheels, nicely sprung. The stoker however is almost directly above the rear wheel taking every hit. High volume tyres help.

Just for your info, tandems often use a 140 wide rear axle. This is to enable a wheel with no dish to be built and therefore is super strong.

As mentioned above, be careful with the front end geometry if you change the fork. On a solo the geometry is set up so that the bike responds to rider movement and helps steer the bike. On a tandem things are different, you don't want the thing steering itself every time the stoker moves about. So be careful to get a similar raked fork, over 50mm of rake is often found.
Have you eliminated a warped front rim as the cause of your judder?

With regards to cranks. There are specific cranksets available but you could quickly start spending quite a lot. Try JDTandems for Tandem parts. Personally I would go the drill and tap route.
Have fun.