Stuck: Bike compatibility problems with Tacx flow to use Zwift

So I bought a Tacx flow a while back to use zwift, but realised my bike is not compatible with the trainer in the same way I imagined.

I was given a QR skewer with the purchase on EBay, but my bike has a screw in bolt axel on the back wheel. I’ve been deliberating so many options such as:

  • buy a whole new back wheel which has the correct axel, but where do I start and what wheel do I need? How do I know which one is correct? This bike model doesn’t even come up when I google it, so how am I supposed to find out?

  • I buy one if Tacx’s thru axel kits, but I don’t even know if they ar compatible with my bike and even if so, what size I would have to buy?

  • buy a new bike and or trainer.

I will attach images below, but I really am a complete noobie when it comes to bikes and as much research as I’ve tried to do, I just can’t figure it out. If anyone can just tell me a rear wheel to buy, or tell me what I can do to get it working, I would be eternally grateful

as a start i would take out the existing skewer on the bike and replace it with the one included with the trainer. All trainers like the one you bought come with a skewer to be used with it.

As my current bike is a bolt on/solid axle variant, I don’t believe I can use a QR skewer through it. At least that’s what I’ve seen online during my research.

Yes, hopefully your bike has a rear axle width that works with the thru axle adapters from Tacx. What is the distance between the rear dropouts in mm?

Background: a friend has a Tacx Flow Smart that I’ve helped configure with two different bikes.

The short of it is wheel on trainers are mostly “agnostic” of what you put on it. The only factor is there has to be something to “bite” (a nut or end cap of a QR skewer) and there can’t be anything interfering with the clamp on the trainer. The reason they include a QR skewer (part T1402) is because the lever on most QR skewers interferes with clamping the trainer closed.

In your case, it seems your bike has a nut on either side of the drop-outs, which should be enough for the trainer to clamp to.

If you could, take a photo of the bike as you ATTEMPT to install it on the trainer - specifically, the interface between the trainer and axle nuts. I’m unclear why this wouldn’t work as-is.

NOTE: the cylinders on the trainer that contact the wheel axle/QR skewer can be pre-tensioned or backed off - you may have to adjust this to get the right width. See page 7 in this PDF:

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This bike doesn’t have a thru-axle, it has a solid axle. Replacing it with a QR axle is often possible but replacing the rear wheel would be less effort. To understand which wheel to buy, you would need to understand wheel size, the width of the frame between the dropouts (probably 130mm or 135mm) and the type of gearing on the bike (guessing a 7 speed freewheel).

I agree with @Otto_Destruct - it seems like it should work as is, but if not, you’d need to convert to a QR wheel or replace the axle.

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Thank you for all the responses!

See, I assumed as much as well, but it is misaligned when it does fit in! Picture below. When the adjuster on the right side of the screen is all the way out the nuts do fit in and hold fairly solidly. However, when I have loosened the adjuster, the wheel nut is very loose.

The misalignment means the tyre scrapes along the sides and doesn’t put out much power at all.

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If the right side of the trainer can’t be screwed in more without losing a solid connection, you might try adding a washer (or even two) under the left side axle nut. Then screw in the right side of the trainer the same amount.

I’m also wondering if the trainer is hitting the rack support and whether that’s interfering with your ability to get good engagement with the bike.

A narrower tire would probably help a little as well. Look for a “trainer tire” if you want to try that.

Unrelated - it looks like your rear derailleur hanger may be misaglined - you might want to have a bike shop check it. That won’t affect the bike’s fit to the trainer though, just shifting. Or perhaps my perspective is off.

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It’s more the fact I can’t loosen it anymore without it compromising the fit.

I can try the washer trick and see, might work never know! I do plan on getting a thinner tyre, this one is currently 700c x 38 and I know that’s on the large side. However that shouldn’t affect the alignment.

In terms of the problem then, would you say it’s not about the axel itself but purely about the alignment? As ideally if I can fix without a new tyre or axle adapter that would be preferable.

The adjuster that meets the axle nut on the right side of the photo really has to be loosened to bring the tire toward the center of the resistance roller. So the question is how to fix what happens as a result. If the fit with the trainer is too loose when the right side of the trainer is farther from the center line of the roller, then you need to do something to make the bike wider on the left side. That could be washers, or perhaps a thicker nut on the left side.

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No problem, that’s really helpful as it at least narrows down my problem somewhat.

I’ll try a couple of solutions and see what I can do. Thank you again for your help!

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I’m not there so I can’t tell you how hard you had to press on the leaver to tighten the clamping mechanism. If you have done everything up fairly tight before you even press the lever shut all it will do is force the trainer supports apart.

What I can tell you is how lose the clamp can be before you finally press the lever. Paul’s advice is good re the right hand adjuster. What I did is from the position in your picture undo the left hand lever. Does the bike feel like it is going to fall out of the clamp. If the answer is no keep undoing the right adjust to the point where the bike is just about to fall out and you have to hold it upright yourself by hand. At that point press the left lever back down. Does the bike feel sturdy and has the wheel moved towards or onto the middle of the roller. If the answer is no you will probably need to use washers as Paul has explained.

You beat me to it.

Right side: screw the adjuster sleeve in such that the tire is reasonably centred. (note: it doesn’t have to be exactly centred, just more so than now)

Measure the gap on between the contact point on the left and make a note of it. Take the left side nut to an industrial hardware store and find a coupling nut with matching threads:

I’d suggest buying a few of different lengths in case you need to fiddle with width a bit.

CAVEATS: too long an extension could put excess stress on the axle, resulting in it bending. Solution here would be to find a longer axle which would extend deeper into the above coupling nut. (I would still use the long coupling nut to give the thickness for the trainer to bite into.

I take ZERO responsibility for you breaking your bike or trainer… but if it were me, and the connection seemed solid (no flex) I’d probably go full send just with the coupling nut, without an extended axle.

Wow. That was a wall of text.

Thank you to you and Ian! I will have a play around and see what I can do, maybe resorting to trying different nuts etc.

Should none of that work, is the alternative to find a new bike wheel or new axel that is slightly longer? Or would even getting a direct drive trainer be a possible solution at worst case or would my bike still not be ideal for it?

Apologies for noobie questions!

You can get replacement axle nuts designed specifically for this purpose (longer and with a cylindrical end) from Tacx and possibly others as well. Just make sure the thread is correct for your hub.

Thanks for the reply! When you say thread is correct for my hub, what do you mean? Again, very much a newbie when it comes to this!

Solid axles come in at least two different common standards of thread (diameter and pitch), Tacx has parts for both but you need the correct one to not damage the axle. (I’d guess yours is the imperial one (3/8 inch x 26 tpi) but you’d need to measure the thread to be sure.)

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Are those the ones they call thru axles or do they sell actual solid axle parts too? I’ve seen the thru axles in other threads before but wasn’t sure if they would be compatible as mine is a solid one.

Your bike does not use a thru-axle. That’s a different system.

As @Anna_Ronkainen mentioned 3/8" is the most likely one.

10mm is also possible but less likely.


Thank you for all the responses in here so far! I’ve tasked my dad with getting me a longer nut from the shop tomorrow and will update if it helps align it or not.

As a secondary option and since I am due an upgrade, I am looking at a new bike on the cheaper side. Seen this one pictured below on eBay and while it’s hard for anyone here to know for certain this will work, does anyone have any tips on what to look out for to get a bike that’s easily compatible with the Tacx flow? This one I’ve seen is a Fuji A1 6061 Aluminium has a QR skewer by the look of it, and slimmer tyres that can actually be easily changed, rather than my current clunky one that was handed down. I had been given a universal Tacx QR skewer when I bought the trainer so that should work, or I could buy one off their website as only cheap.

P.S - I’ve never known how hard it is to find specs on certain bikes, just seems manufacturers don’t even list bikes on their website when they get more than a couple years old!