Cervélo Seat Post Screw Failure

Triathlon Forum
1

Hello P#C Cervélo drivers.

I had one of the stainless steel cap screws that lock the seat post fail as the head of the screw cracked off.

(I use a torque wrench to set the load)

It happened as I hit a sharp bump in the road. It may be an anomaly but I wanted to get better screws just in case.

There was no corrosion visible at the failure area. Our local bolt company told me that stainless is not rated for strength and quality varies.

If this happened in a race I would be toast, not crashing, just having to stand the balance of the race.

My seat dropped down about 3 or 4 inches to bottom out and since it was near the end of the ride I could finish standing up.

I investigated getting a rated steel cap screw - grade 8.

http://www.incomsupply.com/customers/specdata/cap.html

I bought 100 each of the proper size for my bike - 5Mx25 for about $7.50 or $.075 each.

These screws have a tensile strength of 150,000 psi. http://www.ababaqa.com/

Also titanium screws are very strong. 150,000 to 160,000 psi and do not corrode easily and are light (about 60% weight of steel screws) but expensive - about $4.45 each.

The correct size for my Cervélo is M5x25

http://www.racebolts.com/index.php?main_page=page_2

http://www.racebolts.com/index.php?main_page=product_info&cPath=623_635_637&products_id=179

Cheers,

Neal

2

I’m confused. Are you saying that you’re starting a business as a cervelo seatpost screw replacement vendor with 99 screws in stock, or are you asking if it’s worth spending $4.38 to save the 1 gram that you might save going with the titanium screws?

3

Hello pito00 and All,

Funny …

No neither - but if you send me a self addressed stamped envelope (SASE) I will send you a couple of the steel screws at no cost.

Offer good until supplies run out. And actually the steel screws weigh 5 grams each and the ti screws 3 grams each so you save a whopping 4 grams if you want to buy titanium (but not from me).

Cheers,

Neal