2 bikes broken in 18 months


I ride a cheap-ish aluminium bike inside - Spec Allez E5. 2 have failed in about 18 months. I couldn’t believe it when I started hearing some clicking, and noticed another crack in the seat tube/ top tube junction- exactly where it happened on the old bike.

The old bike was used indoors from winter 2019, the new one since about April/May 2022 - my riding is probably 60%+ indoors. A couple of thoughts that may be an issue…

  • I shuffle around on the saddle a bit to find some comfort indoors
  • I use a rocker plate

New bike (April 2022)

Old bike

Could be an indoor cause.

Could be an outdoor cause? Dropping off a big kerb anywhere regularly?

Also might depend on how long you’ve had these bikes from new?

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Old bike was 2nd hand, and I used it outside a bit. As above, it became my indoor bike in winter 2019. The new bike was bought new in 2022 and used exclusively indoors.

Contact Specialized. If you’re the original owner then I believe there’s a lifetime warranty in place on those frames against defects. And a cracked weld with no obvious impact to cause it should qualify for warranty replacement.


Sure, I’ve emailed the shop I bought it from this evening, and will go direct to Spec if needs be. However, this clearly isn’t normal, and to happen on 2 separate bikes (and models) in such a small time period suggests it might be a “me” issue. I’ve never seen or heard of similar, but I assume it’s from using it on the trainer.

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Well I’m afraid that second hand means that anything could have happened to it.

But strange that it’s happened to a new one as well.

Unless you’re clamping it too hard when you clean it or maybe when you transport it ?

The new bike literally hasn’t been off the trainer since it arrived. I use towels to keep the bike sweat free and occasionally just wipe the bike down on the trainer.

What I worry about is the same happening to a 3rd bike in a row. It’s just inconvenient and feels super wasteful. Wonder if a carbon bike might actually be better.

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In your case I suspect too much power…


Wow that’s crappy. I would definitely try to get a new one through warranty.
Fwiw, I’ve had the same caadx strictly indoors with no issues for 3 years now.

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How much seatpost have you got inside the frame? Mayne its too short, and puts dtress on thay junction?

I do think that riding on the trainer puts more stress on the frame, because the bike can’t lean. But a rocker plate should help with that a bit.


I was thinking this also. A pic of the full setup would be helpful for diagnosis. Likely some setup issue rather than manufacturing defect.

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Sad to say I used to ride my aluminum specialized diverge on the trainer and the exact same thing happened. Granted it took years of trainer use, maybe 4 or 5. But it started making creaky noises at first then upon putting it up in the stand to prep it for an early season gravel fondo I saw the cracks and likewise the motion within them when stressed. After that for a while I used it just on the trainer until I got a new bike and then stripped the diverge for parts and hung it up. Recently I went to “stress test” the seat tube sans seat post and it broke right off so that frame is toast.

Can’t say what would happen when contacting specialized since I never did. Figured it was out of warranty and spent most of its time on the trainer soaking in sweat which doesn’t make a good cause for “normal wear and tear.” Especially since in the late 10s there seemed to be more stipulations in warranties about not putting bikes in stationary trainers. I know not super helpful but just wanted to say I’ve seen it before and I feel your pain.

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Both bikes were specialized? Because pattern starts to emerge given the comments.

From fast view I would also suspect too little seatpost. But seems like fracture caused from side to side movement rather than lengthwise.


Good thought - I’ll check insertion length to ensure it clears the junction. Will get a pic tomorrow of full set up, but there’s nothing majorly unusual about the setup. All I’ve done is set the seatpost height to where I need it, and swapped saddles.


That looks like a weld defect in both cases. That can only happen if you’re wiggling the seat post constantly with a lot of force.

Is the seatpost the same? Is that the wrong size post? Do you have 80mm + inserted? Are you sprinting 1000w+ hard seated? Is the trainer in a hard floor mounted rigidly? Do you have your seat too far forward?

Based on the little information given, and seeing the common area of damage, I would be leaning to too little seat post length and hearing you fidget around getting comfortable. Potentially the saddle is too far aft and you should be using a seat post with (more) set back.
Keen to see/read what you post re-seat post length.

I would suggest a bike fit for your indoor use to stop trying to get comfortable, ensure minimum seat post length is where it should be.
I have been using a (different brand) aluminium frame for the past +24000km since 2020 on a rocker plate as well and have no frame cracking issues.


Seat too far back might also put strain on the junction, even if there is enough insertion length of the seatpost. I have a (carbon) MTB where initially I just slammed the seat back, but I could feel and see the whole seatpost flexing. I’m sure it was putting strain on the top tube/seattube junction, by essentially ‘stretching’ the top tube. A seatpost with a setback helped.

Safe to say the seatpost isn’t a problem. I wrapped masking tape above the seat clamp before removing it, and there’s plenty of excess. And yes it’s the right seatpost - using the stock one supplied on the bike. The seatpost is setback for those asking.

Here’s my unglamourous spot where watts are made. Nothing too unusual…

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Although you have said there’s plenty of poat in the frame, have you gone beyond the marked limit?
It could also be the rocker plate. Everytime the plate goes backwards it has to decelerate, stop and go forward (same the other way but reversed obviously), that deceleration/acceleration force has to go somewhere and maybe it’s getting transferred through the seat post/frame junction. Just a thought.

The seatpost is aluminium, and doesn’t state a min/max insertion, but having worked with über light components in the past on other bikes, where there’s a reinforced area, the clamp point (amount of insertion) looks completely normal to me. The frame has no stated min/max that I can tell, but I’m clearing the top tube/junction comfortably.

The rocker plate only moves side-to-side, but I still wonder whether the motion contributed. Then it could actually be a good thing, allowing some movement, possibly reducing pressuring/flex on the frame…:man_shrugging: