7-speed cassette on a Direct Drive trainer

I am using an old but great bike on my current Wahoo Kickr Snap wheel-on trainer that is 7-speed. I’d like to upgrade to a Direct Drive trainer, but the 7-speed cassette does not naturally fit.

I’ve read the threads I could find on the forum regarding 7-speed cassettes on a Direct Drive trainer and watched the video of the individual simply putting in spacers and filing one down for rivet spacing. OK, so theoretically it works.

I’m curious if we have any Zwifters that are actually running a 7-speed on a Direct Drive trainer and how it is working for them. Does the cassette positioning with the spacer leave it in a place that works for the derailleur and it shifts well? Are you happy with the end result and your ride on the Direct Drive? I’m thinking of the Wahoo Kickr Core or Kickr though would be open to other units if one works really well with a 7-speed.

Thanks for any insights folks have

This article addresses using a 9 speed on an 11 speed hub with a standard 1.85mm spacer.

I am not sure but you may be asking too much to attach a 7 speed cassette onto an 11 speed hub that come with most trainers. You may be able to space it out but I doubt any indexing would work. If you have downtube shifters perhaps you can use friction mode?

With the investment you’d be making in a direct drive trainer you might be better off trying to pick up a pre-owned 11 speed bike to get the full benefit from the trainer.

Yes, as stated in posts on one or more of those threads including the link to the YouTube video, we used a 7-speed mountain bike on a KICKR direct driver trainer for years. It shifted properly.

More recently we’ve switched to an 11-speed group set on a cheap road frame just to have the common platform for riding road bikes outside.

The same adapter that makes the 7-speed work on a KICKR would make it work on any direct driver trainer.

  1. 7 Speed Bike on Wheel-off Trainers: Your seven speed bike will probably work on a modern direct drive trainer. There’s a YouTube video showing the concept and the adjustment that is needed for a seven speed cassette versus what’s needed for an eight, nine or ten speed cassette. Those 8, 9 and 10 speed cassettes will go straight onto the 11 speed direct drive trainer with a simple adapter. For 7 speed use, you need to add a second spacer, 4 or 4.5 MM, and file a couple of small indents in the aluminum spacer. Our local bike shop provided a 4mm spacer for a couple of dollars and we’ve been using a 7 speed triple from the 90s on a 2014 Wahoo KICKR for months.Here’s a video that helped me:
    https://www.youtube.com/watch?v=Jrd5XAQfgaA
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You don’t mention the bike frame but if it is steel, you could spread the dropouts.
I did this to an old schwin frame to make a dedicated trainer bike.
I went from 7 to 11 with no problem.
You will need a new shifter.

@Joel_Larner: unless you want to convert your bike to 11-speed, there is no need to spread the dropouts, and there’s no need for a new shifter. You just need to put a 7-speed cassette on the trainer hub, with the adapter, as explained above.

Thanks for all the replies everyone. It sounds like the spacer approach works well. That’s what I needed to hear to potentially go for the Direct Drive upgrade.

The old bike on the trainer is a 25+ year old Trek early carbon from that has carbon tubes in the main triangle then aluminum stays and fork. Not something that would react well to attempting to spread to take a 9-speed cassette. I’ve done all the work on my bikes for 35+ years so considered replacing the shifter, derailleur and cassette to make it a 9-speed but it is clear the frame and wheel won’t fit it. I don’t want to put my good road bike on the trainer and this older bike still runs great, so it works fine on the trainer, just not a fan of how the Wheel-on trainer rides. If the solution is as simple as putting spacers onto a DD trainer I’ll gladly do that.

Sounds good @Joel_Larner ! I really enjoyed reading all the responses because I still can’t see how a 7 speed frame is going to fit into a modem direct drive trainer that comes with an 11 speed cassette body. It just seems to me that your rear triangle is too narrow. Of course I am making the assumption that the cassette body is fixed and can not be replaced. AND the splines on the body need to match up with the 7 speed cogs. However there are others here who say they have done it so I’m sure it’s me that is totally missing something and I hope it all works out for you.

@Bob_Gorman_Splunk_65 The Kickr’s say they are compatible with standard 130/135mm quick release skewers. The dropouts measure 130mm so I expect it will fit on there. The cassette comes off the freehub the same as a 9 or 11 speed does and the alignment grooves are the same pattern. So it’s a question of the dropouts fitting on the Kickr, can spacers take up the additional width of a 9-speed cassette, and with the spacers does the cassette end up in a position within the throw of the derailleur. If I decide to go this route I’ll post the results.

That should work then. My 1988 Bianchi 7 speed is 126mm and would be an issue. Plus back in the day we rode freehubs so I don’t even have cassette cogs for it. It sounds like your 7 speed is a lot more modern. Keep us posted!

130 mm is what current quick-release road bikes have as well. The rear end didn’t get any wider, only the freehub got a little wider but mainly the cog spacing just got tighter and tighter.

There is plenty of extra movement in the derailleur (hence the limit screws) so that shouldn’t be an issue, the only thing is that you may have to adjust cable tension and possibly the high and low limit screws as well if the cassette does not end up in the exact same place relative to the dropouts. (But the difference will probably be one millimeter or less, unless there is something very unusual about your setup.)

@Anna_Ronkainen yes I agree, theoretically the adjusting cable tension and limit screws should enable biasing the deraileur to whatever the center and limits of the cassette are. I’ve also seen situations like this that the cassette is beyond the reach limits of the deraileur as mounted. Hopefully this is pretty easy.

We shall see what happens. I ordered a Kickr Core (no-one has the Kickr v5) and picked up a 4.5mm spacer. Will post on this thread what I get for results.

It works ! I successfully mounted the 7-speed cassette on the new Wahoo Kickr Core and it works great. As the video previous referenced asserts, it required a 4.5mm spacer with notches ground out for the cassette rivets (see spacer and cassette pictures). I used a Dremel to grind down the notches and it was easy to align the notches in the right spot behind the cassette. I’ve also included a picture of the bike mounted on the Kickr Core.

Ultimately the Kickr Core rides sooooo much nicer than the Kickr Snap. Far smoother and most notable is easier. Given today’s training plan workout and how it felt vs previous workouts, I’d estimate I was consuming about 5% power in the friction and deflection of the tire on the Wheel-on trainer roller. That power is not measured or seen by the trainer or therefore Zwift because it is occuring outside the measureable system. It’s possible the spindown test tries to account for this, but I definately felt a difference. In the end, the change to Direct Drive, even with just a 7-speed bike is well worth it.

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Going back to this, I have a 9 gear 11/32 cassette on my bike, if I go for a Kickr Core, do I just need to buy a similar one and fit in the machine?

Thanks

You may need to install a small spacer (which comes with the Kickr Core) behind the cassette. The Core states it works with 9-speed cassettes. Having not installed a 9-speed I can’t speak for sure, but that’s what the literature says.

Oh ok I don’t need to buy an additional spacer then ? They all come with it?

I can’t say that for a fact since I have not mounted a 9-speed cassette. What I know is simply the Wahoo Kickr Core is spec’d to work with 8, 9, 10, and 11 speed cassettes and it comes with a spacer. I don’t know about other direct drive trainers and what they ship with.

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