I went out for a short ride last night only to discover a nasty buzzing sound coming from what I thought was the water bottle cage. The sound got louder as the ride went on. I came home and as I got off the bike the saddle dropped to the ground.

I looked over the saddle and couldn't find any damage at first. I then noticed one of the rails was cracked. Not cracked all the way through but obviously enough to allow the saddle to become loose. The saddle is a Tune Komm Vor. I find it very comfortable and I've only had it a month. I'm below the weight limit by 25 lbs and I tightened the saddle to 5nm using a Ritchey torque key.

I also own a speedneedle and had to tighten it every once and awhile. I ride a 2012 NXR and I'm wondering if it's a issue with the compatibility with carbon railed saddles and the Time seat post or an issue with the torque value I'm using? I can't find any values on Tune's website. I haven't had an issue with my Arione saddle coming loose.

Any insight would be appreciated.

Any pictures on how it looks and how the seatpost is? I'm using a Komm-Vor on my CX with Omniracer, Tune Starkes Stück and now KCNC Ti-Pro Lite seatpost. Using another one on my mtb with AX-Lightness Europa seatpost, also tried with Syntace and FSA SL-K seatposts, never any problem.

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/jonas l
http://cerrol.wordpress.com (my cyclingblog)

Attached is a photo with the speed needle installed. I have taken of the Komm vor so don't have a pic. The crack is on the right hand rail just in front of the front "yoke".

Second pick of the Ariione isn't mine but shows a better pic of the post.

I found that the Ritchey torque key wasnt very accurate. It pretty much crushed everything I owned that was rated at 5nm. I bought a Park torque wrench and now tighten everything at least 10-20% lower than specified nm allowances. I've had much better luck since. Not saying that's the cause, but I would think about investing in better tools for pricey carbon fiber bits.

Funny you should mention that. I attached the saddle again using my torque wrench and then used the Ritchey torque key to see if it would go tighter. It did. I'm thinking the torque key is probably 6 or 6.5.

I'm still wondering what the recommended torque is on the Tune Komm Vor saddle is? I've seen other carbon saddles as low as 4nm. If Tunes rails are 4nm I can see why a saddle may come loose.

I have a Time seat clamp with Selle San Marco carbon railed saddle. Never came loose or had an issue.
I use a torque wrench and some grease on the threads of the bolt for the seat clamp. I think that is key.

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TIME RXR

What do you use as a torque setting.

A saddle rail doesn't have a max torque, it can't, since you don't turn it.

The problem with a torque key that's 5nm is that you can't go up in little increments. When you have two bolts holding something down you don't want to torque one up to 5 and then the other one. You want to go in steps of 1Nm or so when handling weenie stuff like carbon railed saddles.

Also there's a world of difference between max torque and recommended torque. Recommended torque is usually the lowest torque you can get away with, especially if you are connecting two parts form different manufacturers. I don't think I've ever used more than 4Nm and I've used a Komm Vor and Komm Vor+ with a bunch of different seatposts. That was with greased bolts, too.

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"Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.

Is the KonVor one of the ealier versions? You would know because these had some inserts were the seatpost clamp into the rail (smaller rails also).
Tune had some problem with these saddles and some of the later versions with bigger rails.

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www.royalbicycles.com

I was asking what you torque you use when clamping your seat post to the seat rails.

I just received my second tune saddle from fairwheel. The saddle is constructed slightly different from the first I received a few months back. The "new" seat has a web like piece on each rail at the back which looks like it connects the rail to the seat. The first saddle doesn't have the webbing. Which is the newer seat???

I didn't mean to come across as a , sorry. I was referring to this:



As a saddle manufacturer you can state a recommedended or max. torque, I suppose, but it would really just be a more or less educated guess, as they don't know what seatpost you will be using. You don't apply a torque to the saddle rail, you apply a force by clamping down the seatpost head. That they could spec, but you would never know when you got there, unless your seatpost came with a conversion table.

I believe scienceiscool wrote a really good explanation, it would be worth your time to look for that.

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"Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.