seat keeps slipping down roughly half an inch
 

Hello,

my seat post keeps slipping down a bit. i've tightened it as hard as i can....it takes a small allen key that i can't get a lot of torque from.

it's a carbon seat post and a carbon frame so i'm scared of tightening it too much.

clearly i need a torque wrench.... a couple questions.

what is a good torque wrench to get?

how come every torque wrench i've seen online is a socket wrench? my fastener takes a small allen key.

thanks.

are you using carbon assembly paste on the post? for torque wrenches i like dial or open beam type for the stems and seatposts. i have a sturtevant open beam. hex bit sockets are available from many manufacturers and fit right on the torque wrench

Always use carbon assembly paste on carbon parts and you will have no need to over tighten bolts.

http://www.qbike.com/cgi-bin/find.cg...assembly+paste

It'll most likely be a 4mm or 5mm seat collar he's tightening. In which case, it is definitely possible that it is already damaged from overtorquing. And what #2 said, use carbon assembly paste, in addition to double checking that the post is actually the right size for the bike. e.g. 27.2 and 27.0 looks awfully close.

Warren & Brown make great torque wrenches. You can convert from socket to allen key by buying the socket of the same hex size as the allen key.

mis-matched seatpost diameter would be my guess, too. or is there something else, e.g., you are a clyde *and* the allen wrench's handle you are using is only 5mm long off the center?

A torque wrench is a good investment, but make sure you get one that has the range you need. Do a survey of the fasteners and take note of the recommended torque. As with most tools, price is proportional to quality. Those who wrench a lot often don't use torque wrenches because they've developed the feel with experience. Personally, I use one. I've been eye-ing this wrench and it come with 6 hex bit sockets:
http://www.artscyclery.com/descpage-SHTW.html

Also, these hex bit sockets adapt the square drive on a torque wrench or socket handle to the fastener. You'll need to match the drive of the wrench to the drive of the socket. I use these hex bit sockets almost exclusively in my workshop. When mated to a socket handle or driver, it makes wrenching nice.
http://community.craftsman.com/Craft...-Drive-reviews

thanks guys. i don't think it's damaged as i've been tightening it with a smell hex key, it's pretty tough to get the strength to over tighten it with such a small key. As for the post size, i imagine it should be the proper size, i bought the bike new fully built already.

thanks for all your help.

hello, two more questions.

i'm looking to add a Torque Wrench to my Xmas List ( tis the season). i've looked at my bike and it says "max torque 70kgf-cm" what does that mean? is that 70kilograms?

i need to know what to shop for.

also, with the carbon paste, is that a glue? what if i one day needed to adjust the saddle height and the paste is on, would i have trouble?

thanks everyone.

It means ....Kilogram-force per square centimetre

U need a torque wrench in inches or cm to start with.

70 kgf-cm means apply "70 kg of force at 1 cm distance".
It's confusing since force in the metric system is expressed in Newtons (N) and it's more common to see torque expressed as "xx N-m", which means apply "xx N at a 1m distance."

Note, 1 kg-f = 9.81N.

Then 70 kgf-cm = 686.7 N-cm = 6.867 N-m. Thus you will need a torque wrench that can measure up to 6.867 N-m.

Here's an easy to use conversion web site: http://www.onlineconversion.com/torque.htm

By the way, check all the fasteners and see the range of torque values. IIRC, the highest torque value I have is 40 N-m. If you're lucky, one wrench will cover all the fasteners.

Have a friend that runs a bike shop and swears by these. He tries to sell one to each customer that buys a Trek frame with an aerodynamic seat mast. At $114 per seat mast it is a money saver.

http://www.ritcheylogic.com/dyn_prod.php?p=05-252-100

http://bikeforums.net/attachment.php...hmentid=178801