Carbon Saddle Rails - Weaker or Stronger?

I know carbon saddle rails are used to save a few grams, but I haven’t seen anything about their relative strength compared to alloy rails. Does the oval shape give them added strength?

I’m a big rider and would like to try the S-Works Romin EVO with Mirror, but I’m concerned about the carbon rails. Will they hold up as well as alloy rails? I’m strictly a road cyclist… no gravel or MTB. Any advice would be appreciated before I lay out that kind of cash!


A lot will depend on method of construction (and QC). Some brands have weight limits (for example, Selle Italia 90kg iirc), so it’s worth checking.

They’re strong af… I know a guy who weighs 315lbs and has been riding a carbon railed Fizik for years without issues, after bending chromo rails on the saddle that came with his bike. Not sure what your definition of “big rider” is but I’d be very surprised if you had any issues.

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For road riding you’ll be fine. I’ve got the Romin Evo Mirror and it’s a great saddle. For MTB, I did break a S-Works Phenom with carbon rails, so it’s not ideal for jumps and hard riding.

How do you like it, and would you mind posting a profile shot of your Mirror? I cannot find one in stock and all the web photos I see fail to show how pronounced the upsweep at the back is… I’ve been strongly considering buying one but, since I can only find them online, I really don’t want to blow $450 on a saddle and then find out it’s way flatter when mounted on a bike than it looks online.



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I’ve been really impressed with it. I’ve tried on my road bike, gravel and on the indoor trainer. The biggest improvement was on gravel — it’s amazing how much rider suspension it adds. Basically it’s got squish factor but doesn’t instantly rebound like a closed foam saddle does, it’s got a soft rebound. On the road bike, still comfortable, was very happy with it but I also liked my previous saddle, Power, and the firmer platform that the Power offers still works really well on road rides (at least sub 2 hour). On the indoor trainer, it wasn’t a magic bullet that solved my issues with sitting on the trainer. I can sit longer on the Romin Mirror than other saddles but I still get pressure issues at around 1 1/2 hours, I’m guessing it’s just an unavoidable part of long trainer sessions when you don’t move around much. Overall, very happy with the saddle.


Excellent feedback, really appreciative it. I think I’m gonna pull the trigger, sounds like what I’m looking for!

Man, I really want to try the Romin Evo Mirror, but SO much money.

Regarding the carbon rails, they are bulletproof until they are not. I think for a bike where you don’t expect to crash and risk having the saddle take a non-intended hit, they are great. I had a good friend have a very slow innocent crash on his gravel bike, and the awkward hit to the ground broke his Fizik Argo Tempo R1 carbon rails right behind the rail clamp.

So for road riding 100%, for gravel riding if you’re willing to risk the cash, but for MTB I’d stick to a metal rail.

** Racing crash scenarios excluded from analysis

I have exactly the same on my Power Mirror. The only time I’m ever aware of it is (oddly) for the first 5-10 minutes of a road ride, and then after about the 90 minute mark on the trainer. But I’ve done 3 hours on the trainer with it, with only moderate discomfort, whereas 2 hours inside is pretty much the hard limit on my other usual saddle (the Aeolus Pro, which I can ride for 4+ hours outside)

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Funnily enough I’ve found that getting a cheap, padded saddle seems to work well for me when on the turbo, it means I can last longer than 90 mins now. I got this for £30:

Also a good saddle for the Dad bike when I don’t want to be wearing padded shorts.

Usually I use a Repente Quasar, can spend all day on it on the road but after an hour on the turbo I start feeling it.

To me that rings true as well, maybe I’ll try that saddle. My favourite bibs on the trainer are a pair of Specialized SWAT MTB bibs, they’ve got a big ol’ soft pad, kinda ridiculous soft — not great for riding outdoors on but indoors soft and squishy actually seems to work better.

I’ve seen steel rails break and many carbon ones too but not so many Titanium ones. I’ve used carbon railed Fizik and Selle San Marco and I do believe they are relatively strong but long term I trust a Ti or steel railed saddle more.

If weight is a priority then go carbon but if not then look for the same saddle with rails that are less susceptible to failure from nicks or sharp edges. I’m sure the pro carbon people will shoot me down though…

I believe that seat post/saddle clamp choice can also be a consideration.

For Dad bikes, Brooks Cambium FTW :slight_smile: