Direct drive trainers and carbon frame fatigue

[DrIoannis]

I was thinking of buying a direct drive trainer, a smart one but I am worried about the fatigue that might appear in the rear carbon frame. There are forces that are not "normal" for the carbon frame.

What do you think?

[BernieMoves]

Most manufacturers will tell you whether their frames are safe to use on an indoor trainer. I use mine heavily but still avoid sprints out of the saddle though.

[eucalyptus]

I think it depends on a lot of factors.

First off weight, if you are light 50-75kg is vastly different than if you are +110kg pushing.

Then secondly "how fixed" the bike and trainer is. My Tacx Neo 2T swings very nicely side to side. My impression is that Waho Kickr V5/V6 is much more fixed and not tilting sideways which means all the forces go to the frame instead of the tilting function inside the trainer.

Also what frame you are using, a super thin sub 700 gram carbon frame dont really have much material than if you compare with +900 or +1000 gram carbon frame, hell most chinese frames are north of +1000 gram and they will probably be able to take a lot more beating than a superlight thin frame.

Sum up: you will probably be fine. Just because there are risks doesn't mean it will happen to you.

But personally I bought a new aluminum bike just for this (brand new Scott speedster 20 is perfect for zwift). I would never use a Tarmac SL8 or similar on a trainer and especially not if I were a heavy guy. But that is just my take on it Because I don't wanna take that unecessary risk when it is so easy to avoid...


N+1 bike always

[DrIoannis]

As far as I understand there is a risk and it is not a small one...

I have a BMC SLR 02 Teammachine and I am 88kgr. Just starting to cycle a bit more and was wondering if I could also train in the Winter. I also have an MTB aluminum which I might be able to use it for training.

[EdWiser]

The problem coming when you think you are Mark Cavendish and do a lot of sprinting on a carbon bike in a fixed position. I do support for cycling apps. Am I see a ton of broken frames from all that sprinting.

[DrIoannis]

Well I am not Sir Mark Cavendish for sure .

I might think of using my aluminum MTB for the job. I will use a cassette of 11-30 and we are set...

Another solution I think of is a Smart Roller...

[micmax]

I use an Aeroad (2019/20) now for 4 years, first on a Neo 2T, now on a Kickr Core. 75 kg. Never had a problem with the frame.

[EdWiser]

Smart rollers will not give you as must resistance as a direct drive trainer do to slipping. Same as wheel on trainers.

[AJS914]

As far as I understand there is a risk and it is not a small one...

Not a small one?

I think the risk is very small and the only problem will be when the rider doesn't use common sense. I mean that the frame in fixed in a plane. Don't try to sprint with side to side torque and you'll be fine.

Getting some kind of rocker plate or motion system will also help but still don't apply aggressive side loads to your frame.

If you do normal training on a trainer, between endurance and vo2max power, you'll be totally fine.

[goodboyr]

You know this question gets asked every year just before indoor season. And every time it gets asked the same discussion occurs. Just imagine the number of carbon frames on direct drive trainers these days. Most bike frames are carbon and most trainers are direct drives. Yet no one talks about this until just before indoor season. And no one talks about this just after indoor season is over. So......draw your own conclusions.

Sent from my SM-S918W using Tapatalk

[TobinHatesYou]

Based on my own experiences, your trainers will develop issues long before your carbon frame will.

[warthog101]

Have killed a cheap aluminium frame with carbon seat stays a decade or so ago. Aluminium cracked in a chain stay. The very flexible low grade CF seat stays probably enabled it.
Current stiff aluminium frame has been fine but I am now older and less powerful and less inclined to spend time on the trainer. It bores the sht out of me.

[Dannnnn]

Based on the posts I've seen on various forums and FB groups, I could probably count on one hand how many failures I've seen reported.

In fact, I've seen more posts about aluminium handlebars failing from sweat corrosion than carbon frame breaking.

[MichaelK]

I know a few guys on eSports teams. They push some watts and use their A-bikes on turbos all year round. Never heard of any issues.

[ViperFFM]

Not a discussion worth having. From all parts involved in a direct drive trainer setuo, including all the gear you have on the bike, the frame will be the last thing "wearing" out.