Carbon or Steel Bike on Trainer?

Greetings! Is there any reason not to put my carbon bike on a trainer? Should I use that or a steel bike? When I purchased my Specialized Roubaix Comp the guy at the store said he would not put it on a trainer. The last two winters I’ve used my steel-frame Surly Long Haul Trucker for indoor training in an attempt to baby the carbon bike.

Thanks in advance for any help you can offer.

I’ve used my giant propel on two different smart trainers for a little over a year and haven’t had any problems. If trainers posed a serious threat to carbon frames, there would be an industry wide stance against this practice, but there isn’t. Shane Miller (gp lama) noted that as long as you connect the bike to the trainer correctly and are aware that some motions will be different on the trainer riding versus outside riding, such as sprinting (up and down versus side to side), that your carbon bike will be fine. Just be sure to shield your bike from sweat (especially a steel bike), and give it and your drive train some care every now then when the bike is on the trainer.

IMO, I would use a carbon frame on a trainer before a steel bike as steel is more prone to corrosion from sweat and you would need to take a few extra measures to protect a steel bike.

Thanks, jsteelfex. I’m being a over-cautious but wanted to hear from others. Obviously, I see a ton of people online who put their carbon fiber bikes on a trainer. Mine is a “dumb trainer” but that probably does not make a difference. I plan to use TrainerRoad for the first time in order to do quality over quantity so am thinking the better bike that I ride all the time may be the best way to go while indoor?

No probs with my carbon frame - technology of carbon manufacture these days is light years on from early fractures which caused a lot of commotion.

Specialized says not to use a carbon bike on a trainer. I think they are being overly cautious though. I’m not sure anyone really knows the answer, I’d love to see some real stress test studies.

Yeah, and when you walk into the workout room in Specialized HQ… you see which brand’s bikes mounted on the trainers??? (been there and done that, and they aren’t Treks)

This whole manufacturer warranty issue is insane when they directly violate those with their teams and personal use. Shane Miller has some great stuff on the topic. I can search and find the video for those interested. But they are being very lazy in not actually addressing this issue.

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The issue is more the components than the frame material.

How corrosive is your sweat, and how diligent are you about wiping your sweat from brakes, derailleurs, headset cap (and headset), crank, bottom bracket cups, and shifters?

Some have good maintenance habits and/or benign sweat. Or, they use sweat nets and have good maintenance habits.

I have superfund-toxic sweat and am notoriously negligent. My solution is to lash an old beater to the trainer and save my decent bike for the road.

True, maintenance and wear from indoor use is an issue. And it should be dealt with appropriately. Proper cooling to start so you minimize sweat to begin with, and proper maintenance and cleaning for continued use.

But the core question in the OP relates more to pure structural issues and that is about the frame and fork, not the components.

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I should have been more explicit.

The structural issue doesn’t matter much. Unless you are some kind of massive watt beast, you’re not going to tear up a frame or stays on a trainer. Sweat isn’t going to kill carbon or steel, though you might get some powdercoat damage with excessive sweat on metals.

So, in that light, I’d say the OP’s question is, perhaps, not the main factor in deciding which bike to put on the trainer. I hope that was not inconsiderate or off-topic.

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Not inconsiderate at all! Before my OP my general thought is that its fine to mount my carbon bike on the trainer. I feel like there is conflicting advice BUT that most folks are doing it. In terms of maintenance, I’m so-so at best. I can up my game in that department because I sweat a lot.

The other factor is the Surly needs tons of maintenance and it will cost. The chainring and cogset are shark toothing. I get the good bike into the shop once per year for a makeover in addition to minor stuff by me. So, it may save money to stick the good bike on the trainer.

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Interesting topic. You don’t hear of masses of frames breaking on trainers, but some manufacturers are very vague about it. I recently asked the same question to Specialized and got an equally wooly response. They make no statement about it in their warranty policy but there is something in the users handbook recommending if you do then a wheel off trainer is better and advise against A frame trainers. They recommend getting your bike checked by a dealer every so often if it’s on a trainer, but then follow it up with a statement syaing that use on a trainer MAY invalidate your warranty. They make no clarifications on the circimstances.

Ironic that Tacx have some nice S Works bike on trainers in their ads, they partenered with Zwift for the California challenge and you can now unlock a bunch of cool S Works stuff on Zwift!! I wonder why Specialized haven’t asked them to remove them, or added a disclaimer to the ads?

To add to the considerations of wear. Don’t assume that carbon is immune to these concerns.

Own it’s very own, there are no corrosion issues from our sweat. But when carbon mates next to and touches aluminum, there is a strong chance for galvanic corrosion.

Places like:

  • Water bottle mount inserts,
  • Seatposts into frames,
  • Stem to handle bar and steer tube,
  • Hood mount strap around handlbar,
  • and anywhere else that carbon touches metal (especially aluminum) are points of concern.

Leaving sweat and the salt from it, in contact can result in dramatic destruction of the surrounding parts.

The overall issue of sweat and maintenance on bikes inside is worth real consideration. Good fan to limit sweat to begin with and proper cleaning along the way can prevent premature demise of frames and parts.

K. I’ll stick my head in the noose here.

I know everyone does it, and I know manufacturers condone it, but rigid trainers don’t sit well with me from a design standpoint. (And I’m no engineer, either.)

On the road, most forces at the dropouts are vertical, and any rocking pivots about the contact patch, with the compliance of the tire, rim, and spokes in between.

On a rigid trainer, any twist is focused at the dropout with only the frame compliance in between.

And my concern is not about tubes breaking and carbon splintering, but wear at the dropout faces where they contact the skewer and lock nut. (This is obviously not a concern with through axles.)

This was one of the reasons I opted for rollers when I chose to upgrade my dumb trainer. Just my two cents.

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Those concerns are #4 on my list as one of the benefits of my rocker plate push.

Rocker Plates for Trainers


I broke my Canyon Ultimate CF SLX frame in a standing sprint at 1200 watt on my Tacx T2. People should be made aware that throwing your bike around on a trainer is a big no no.

The most I can see that I’ve put through my carbon frame during the 5.5 years I have had it on the turbo that doesn’t look like a power spike is just 688w. I have worn the rear drive aluminium drop out plate a bit (wore down the head slightly on one screw) and took it to a shop to get a 2nd opinion but they replaced the screw and said it was ok. Maybe it wore down outside however. I think if I eventually get a new Carbon TT bike it will go on the trainer too and maybe I’ll get a rocker plate too but I’m not sure I have the room in my current pain corridor for one.

I’ve put over 20k miles on a 2011 carbon frame indoors. No worries at all.

I’ve used my carbon bike on my wheel on dumb trainer and direct drive smart trainer with no problems. I think the only problem you might have is if you get up to sprint and really row your bike back and forth like a maniac. I do standing drills all the time on my carbon trainer bike and no problems but I’m not trying to hulk smash back and forth.

I think the bike manufacturers are trying to add another case where they don’t have to honor their frame warranty.

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As mentioned above, I think there is potential risk from these hard and active efforts on a traditional, rigid trainer. Even the flex that the Neo trainers have is not enough to help with the high stress issues related to the lack of real movement.

If people want to really get into hard and active sprints on a trainer, using a motion device like a rocker plate is what I consider to be the best option. This adds a degree of freedom on the Roll Axis, which is where the excessive stress comes from due to the side movement we naturally apply in efforts like this.

Locked and rigid trainers apply this loading directly into the bike frame and it likely well exceeds anything they see when freely moving outside. A rocker plate can give some real freedom and cut that loading drastically, IMO.

The other option would be to use rollers or even the expensive bike treadmills, that leave the frame untouched. Those have their own challenges, and are part of the reason I ended up making my first rocker back in 2015.

I think a rocker plate or similar device is useful in this context and has other benefits along the way.

totally agree.
Any bike, made of steel, aluminum, carbon or what ever else is not designed to be rigidly clamped at the drop out like a cantilevered beam. And then being subjected to 1000watt sprints with lots of side to side motion causing torsional load at the frame.

The bike may still be fine, and survive, but that is not guaranteed. I cringe every time I get out of the saddle even for my cheap alu bike on a wheel on dumb trainer. Just doesn’t feel right for the poor bike :rofl:

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