Refresh your contact points PSA

[Bewheels]

Was on the trainer this morning watching some videos with headphones in going super easy....ride with your 6 year old level of easy.

Decided to sit up for a bit. Next things I know I hear a 'bang' at the same time I started falling backwards. Butt hits the floor and my upper back hits the treadmill that is behind the trainer. Both feet are still clipped in. Headphones were ripped off (they are wired and still plugged into the laptop). I look up at the bike to see that the seat is not there but is instead laying in front of me.
I take a second to make sure I basically OK and then clip out of the pedals.

One of the seatpost mount bolts broke.

This seatpost saw about 2 years of active road duty and has been on a trainer for the last 3 years.

Wanted to post this as a public service announcement to check/replace your contact point on a routine basis.

[dogrange]

Geez Brian, that's terrible, and must have been quite a shock! Glad you are OK! Do you think you would even have seen the bolt as a hazard even upon inspection? They are nested in there pretty well . . .

[Bewheels]

Hey Andy - while I could have gotten that buried bolt out to inspect it, even I took it out I highly doubt there would be anything to “see” with the naked eye.

And ... it was startling way to start the day.

[thomas]

Yikes, that is not something you ever expect to happen. Could've been seriously catastrophic. Glad you're OK.

Only one of my bikes has that double bolt setup (a Nitto post). All the rest are Fizik. The front angle adjustment bolt would have to break for that to happen. Seems like the double bolt setup like yours could be most susceptible to this occurring, since both are torqued down pretty hard.

[GrantM]

wow, scary stuff, glad you're ok Brian.

i've got what looks to be the same Deda post on my Parlee, been there since 2010,
maybe time for a new one!

-g

[Tim Porter]

Also glad you're okay, Brian. You prompted me to do a reality check on the stem and HBs on the Hampsten I rode so much this year. No probs found, but there was definitely some clean up followed by re-torqueing that needed to be done. Thanks! Tim

[Bewheels]

wow, scary stuff, glad you're ok Brian.

i've got what looks to be the same Deda post on my Parlee, been there since 2010,
maybe time for a new one!

-g

That's the seatpost.
If you need any extra parts I have all of them except one bolt :)

[Pastashop]

Glad you’re ok.

Is the verdict that the front bolt snapped?.. Looks like it is still in the socket, suggesting the bolt snapped at the head / root. It is a very common clamp design, and one might expect many such failures to occur. Any thoughts on what caused it? Was the saddle shoved all the way back? Was the bolt under / overtightened?

[Saab2000]

Yeah, as a user of Deda posts I’m curious as well. Love to know details of this. Tightness, saddle placement, etc.

Glad you’re not hurt! This type of situation is legit scary.

[Pastashop]

Glad you’re ok.

Is the verdict that the front bolt snapped?.. Looks like it is still in the socket, suggesting the bolt snapped at the head / root. It is a very common clamp design, and one might expect many such failures to occur. Any thoughts on what caused it? Was the saddle shoved all the way back? Was the bolt under / overtightened?

EDIT: meant to say that if part of the bolt is still in its bore, it might suggest that it *didn’t* snap right at the head / root. The fact that it’s still stuck in the socket may be an indicator of something also — e.g., that it’s bent, that there was some side load that wedged it slightly into the side of the bore hole, residue / corrosion,.. Examining the broken bolt closely may also reveal mode of failure — fatigue, impact, corrosion, notching, etc.

It’s important that these bolts be tightened to spec, provided the spec is to pre-load the bolts to prevent relaxation / de-tensioning. My suspicion is that the carbon shoulder of the hole got compressed amd lead to de-tensioning of the bolt, but can’t tell from that angle and with the bolt still in.

[Tom]

You don't expect to fall off the bike when it is locked in the trainer. That can be bad when it catches you by surprise especially if you're in a crowded space with pointy things. I forgot to extend the feet on mine one time when I set up for the winter and I was at about 15 degrees and heading further just after clipping in. It was one of those "Hey, the cellar's tipping" moments before I realized what was happening.

[Chik]

Hucking fell. I'm glad you're ok.

[boots2000]

I know a rider who was injured when his Deda post failed. He got a lawyer and pursued a case with Deda- They settled with him.

[Bewheels]

Catching back up on the thread.

The seat placement - slightly back from dead center on the rails but very much within the range of "normal".

Yes, the front mount bolt broke. That bolt comes in from under the post's head. The thickness of the head at that point is ~10mm. As you can see in the photo, the bold broke flush with the material where it comes out of the head. The bolt broke ~10mm up from the bolt head. In other words, the bolt broke at the spot that it comes out of the head of the post not near the bolt head. I assume that there is some type of stress riser at that spot.

All things considered I was lucky to get away with only a few bruises and some very mild whiplash. Of course now my wife wants me to wear a helmet while on the trainer :)

[zachateseverything]

You don't expect to fall off the bike when it is locked in the trainer. That can be bad when it catches you by surprise especially if you're in a crowded space with pointy things. I forgot to extend the feet on mine one time when I set up for the winter and I was at about 15 degrees and heading further just after clipping in. It was one of those "Hey, the cellar's tipping" moments before I realized what was happening.

A few years ago my cycling team organized some group trainer classes at a local gym. We would take turns being the spin instructor. We opened it up to other groups as well and it was actually kind of popular. Maybe 30-40 people would come out on a Sunday morning to not ride indoors alone. This was all pre-zwift.

We would always get some triathletes that would show. About once a class one of them would fall off the trainer.

[Tom]

I avoid group rides not to mention group classes, but this sounds like it'd be well worth joining just to see that happen. That's some funny stuff, there, that is.

[Scott G.]

When replacing Italian seatposts, Nitto is the Miata.