Swapping big and small bikes on a Wahoo Kickr Core

September 25, 2019 7:17 AM

I'd like to get a smart trainer for me and my son to play Zwift. Is it possible to swap between my old bike (Giant Escape 2013) and my 8 year old son's bike (Islabikes Luath 26) on a single trainer?

I'd like to stay more active this winter and want to get a smart trainer. The Wahoo Kickr Core seems to be closest to what I want. I also want to keep my son fit and I think he'd like the gamification of cycling that you get in Zwift.

However, I'm not sure if it's possible / easy to switch between bikes. The Islabike has a Sunrace, 8spd, 11-34t cassette, and the Giant Escape has a Shimano HG30 11x34, 9-Speed cassette. Would it be possible to attach both bikes to the Kickr Core set up with a single cassette? If not, would it be possible to switch cassettes on the Kickr Core and if so how much work is that?

The configuration / calibration for my son's bike doesn't have to be perfect, it just has to allow him to ride.

posted by Stark to Technology (5 answers total)

Best answer: Current two bikes have different rear gear counts, are the rear shifters indexed? If so you'd need to change so the cassetes match the gear indexing. I can't recall if an 8 cassette mostly works with 9, such that you wouldn't need to switch out the majority of the over drive products to match the cassette to not prematurely wear or not. I seem to recall it's 6-8, 9-11 and 12+, so that might be an expensive upgrade to change the 8 rear to 9. I can't comment on the ease of switching cassettes on the kickr.

I'll also point out that threading the chain over the cassette every time you switch bikes would be messy.

Even with a kickr snap (which I have), with every time you switch bikes, you should re calibrate; needing to do recalibration every time would get a bit tiring.

Might I suggest that if you're looking to invest as much in a kickr core, that you consider also getting a (perhaps used) bike dedicated for the trainer? With a quick adjust seat height it's minimal time to change from one person to the next. If you go with an extra long seat post and a frame smaller than your preference, you might find a frame which is ok-ish for both an 8 year old and an adult... Especially if he's tall for his age, and you're not!

I have one bike both for riding out doors and the trainer. Biking for me is secondary to running, but as soon as I finish paying off for this year of racing I'm going to be buying a used secondary bike to only use on the trainer because switching tires is BS.
posted by nobeagle at 8:12 AM on September 25, 2019 [2 favorites]

Best answer: Switching cassettes is possible, but enough of a pain that I wouldn't do it often. You could both ride a nine speed, but the shifting would be lousy and might be frustrating enough so he wouldn't ride. I suppose you could put an 8 speed on there and have you suffer poor shifting instead...

I totally get wanting the quiet and fancy Kickr core, but the easiest way to switch is to get a wheel based trainer. Actually, since all of this depends on spending money, I'd consider upgrading his bike to nine speed. You'd just need a shifter and a new cassette.

If there's room and you can manage it, maybe get the Kickr core and a used wheel based trainer and ride together?
posted by advicepig at 8:15 AM on September 25, 2019 [1 favorite]

With a Kickr Core you don't have to change gears. The trainer will vary resistance automatically for you.

The 9spd chain on your bike will work with an 8spd cassette, so throw an 8spd cassette on there and be done with it. Then you can switch both bikes on and off and it won't be a big deal.

I rode my Kickr using an 11spd bike and a 10spd cassette for several months before I threw an old 11spd cassette on the Kickr. It worked fine.
posted by spikeleemajortomdickandharryconnickjrmints at 10:57 AM on September 25, 2019

Per nobeagles's MeMail to me, I'm not considering that Zwift's simulation of the course means it changes resistance, but it expects you to shift to respond to that.

I use Trainer Road, which is more of an interval-based format, and the Kickr changes resistance for you, no matter what your cadence is.

So now you either leave the 8spd cassette on there and have a questionable ride (it's going to suck having to shift a lot), or you just get good at swapping cassettes (which you can do in less than a minute, but still). Cassette pliers are a little faster than a chain whip in my experience, but you'll get fast with whatever you go with.
posted by spikeleemajortomdickandharryconnickjrmints at 12:09 PM on September 25, 2019 [1 favorite]

Also, you could upgrade his rear shifter, cassette, chain, and derailleur to 9spd. Just throwing that out there.
posted by spikeleemajortomdickandharryconnickjrmints at 12:13 PM on September 25, 2019 [1 favorite]