mikebian 

A couple of our friends ride their tandem on an old wheel on style smart trainer. They are looking to upgrade to a modern trainer where you take the wheel off and mount the rear triangle directly on the trainer. Has anyone done this?

Rear spacing seems to be the issue. They have a Co Mo with standard 145 mm spacing. The trainers offer a lot of adapters but not for 145. There’s a Trek adapter that is 141 qr but I’m not sure about squeezing the rear triangle 4 mm. Any thoughts?

Thanks

TobyGadd

I'm not sure that it's a good idea to use a tandem on a trainer for long periods. The forces and leverage are pretty different on a trainer than they are while riding on the road, and I'd worry about fatiguing the chainstays, seatstays, and dropouts. But maybe I'm just being paranoid--although even some single bikes have failed on trainers. At the very least, I'd contact the manufacturer to make sure that it won't void the frame warranty.

mikebian 

They’ve been doing this for years now. Any issues with frame warranty have sailed away a long time ago.

spaltzer

Hello Mike,

Rear spacing and maybe weight limits are obstacle that prevent a Tandem from being installed on a Wheel-off Smart trainer. Common Quick Release spacing for Trainers is 130mm, or 135mm, and Thru-axle spacing of 142mm or 148mm. The Hammer (H3) from Saris has a limit of 300lbs including bicycle. Wahoo KICKR is 250 max rider weight. You could add supports to lower the perceived applied weight, an upward force countering the downward force. Maybe a tandem adapter could be made to work with the Trainer? An adapter that would provide the added spacing, and support.

My plug for rollers - A long winded response.
I was able to ride a tandem on TruTrainer's Smart Load rollers linked with Crown Rollers with a friend. He used the ceiling for support, and I held onto a windowsill type hole in a wall for getting started.
youtube DOT com/watch?v=v0jV35klMgo

The Crown rollers helped keep the rear wheel centered, and the TruTrainer's flywheel smoothed everything out and keep our momentum going. You can see it takes a little while for the wheels to spin down at the end.

I my current ideal setup for a tandem on rollers would be TruTrainer SmartLoad Power Rollers for the rear wheel, and TruTrainer's Classic Rollers for the front wheel. The SmartLoad Power Rollers would provide the Smart capabilities for pairing to Apps/games for control-ability and the Classic Rollers would provide a second fly wheel to keep everything going smoothly.
SmartLoad Power Rollers - No change except move the front drum to the closest position to the rear drums, place the linking band into the groove and the existing band next to the groove and let it ride on the lip at an angle. Classic Rollers - remove the front half of the frame and position the front drums backwards from normal use. Link the belt from groove to groove, and you are set. The front drum on the SmartLoad Power Rollers is just relay. The stretched band will pull the Classic Rollers frame out of position, so some means of hold it in place is needed. Rubber feet, carpet surface that the frame can dig into. Wooden frame that both trainers can be lock into place on - whatever.

My dream setup would have a motor rotating the drum for the front wheel. The rear wheel and the front wheel would rotate independently of each-other. This setup would accommodate any bicycle wheel base length! The motor could rotate the front wheel at a steady speed, or as a function of the rear wheel speed or some other metric like power or heart rate.

Alcanbrad

Many wheel off trainers utilize simple spacing adapters to adapt the trainer to the various dropout spacing and QR or thru axle. It would be fairly straight forward to have a machine shop turn a set of adapters that would allow mounting your tandem to a particular trainer. It would require a little bit of work to determine the spacing for each side. My initial thinking is that the drive side adapter would likely not need to change maintaining proper derailleur to cassette spacing. The non drive side would then have to make up the difference.

As for weight limitations, product designers always build in a fair amount of margin. A trainer with a weight limit of 250lbs won't fail at 251 lbs. A design 2X margin is typical in many things but is not guaranteed. You would need to determine what weight your bike/team is placing on the rear wheel and determine your comfort level. (should be easy to do with a bathroom scale and third person).

While this is fairly straight forward, the stresses placed by the wider spacers to the trainer interface may be a point where these stresses may lead to premature failure and is the hardest to determine. The idea of adding support might work to mitigate potential problems with the trainer, however it may transfer greater forces to the tandem frame that would not occur naturally.

If you are not an excessively heavy team and will not be doing high stress riding like all out sprinting, or high power output while standing (i.e. you will be just riding up and down hills while seated), you might be OK, just make sure you consider the failure points and if they are worth the investment.

We have ridden our tandem on a wheel on dumb trainer with no issues, but have not tried it on the smart trainer. I'd be curious to hear your findings.

blacknbluebikes 

A smart trainer is a rather expensive thing to break. I wouldn't consider it on my Wahoo Kickr, one of the less expensive models at a $500 replacement cost. But, heck, call Wahoo and ask them what they think - they've surely gotten the question before.