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Resident Curmudgeon
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Discussion Starter · #1 ·
Jeez! I just bought my new CF bike a couple of weeks ago. Like any new bike there were a few adjustments I needed to make. Wanting to do it right I went to an auto parts store and bought a torque wrench. I had never used a torque wrench before and it didn't take me long to discover that you have to be smarter than the wrench to use it.
The thing is calibrated in ft lbs, inch lbs, and m kg (whatever that is.) A conversion sheet came with the wrench so you can change from sae to metric, but I'll be damned if I can figure it out. :eek:ut:

My seat was a little too high, so I loosened the clamp bolts, put it where I wanted it, then tightened it with a hex key until it would stay where I put it. Then...the torque wrench comes out, and confusion and fear come in. The seat post clamp says 50nm max. Well, there isn't any setting like that on the wrench. I tried unsuccessfully to decipher the conversion chart. I set the wrench to its lowest setting. After tightening to the point I was getting scared, I stopped & backed the bolts out. Just to experiment I tried tightening some stuff on my steel bike with the wrench at the lowest setting. YEA! It finally clicked, but it felt to me like the torque needed was pretty excessive.

I just bought the wrench yesterday & I can return it. Anybody got any suggestions? And no, I'm not going to trash the CF bike and get another steel one. :D
 

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Low Idiot Tolerance
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Yes.

First suggestion is not aimed at you specifically. m/kg is metres kilograms. You may not have worked that out because your nation refuses to leap in the 1970s and adopt the metric system. So suggestion No.1 is adopt the metric system. :)

Suggestion No.2 is take the torque wrench back to the auto shop. Automotive torque wrenches are made for torquing down cylinder heads, not nipping up seatposts.

You need to get a bike specific torque wrench such as a Park, Pedros etc that are made to deal with the smaller torque settings.

This conversion calculator is really simple to use.

http://www.boltscience.com/pages/convert.htm

6nm is about 4.5 lb/ft.

Grumps
 

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Click in the clamp or the wrench, or the bolt head?, etc

Sometimes it's a case where the non-threaded hole becomes a bit threaded by the screw, catching onto it, and then slips to then emit a clicking sound. My double bolt clamp does that sometimes and suggests 35nm.
 

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Resident Curmudgeon
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Discussion Starter · #4 ·
Uncle Grumpy said:
Yes.

First suggestion is not aimed at you specifically. m/kg is metres kilograms. You may not have worked that out because your nation refuses to leap in the 1970s and adopt the metric system. So suggestion No.1 is adopt the metric system. :)
I couldn't agree with you more. It's just plain stupid.

Suggestion No.2 is take the torque wrench back to the auto shop. Automotive torque wrenches are made for torquing down cylinder heads, not nipping up seatposts.

You need to get a bike specific torque wrench such as a Park, Pedros etc that are made to deal with the smaller torque settings.

This conversion calculator is really simple to use.

http://www.boltscience.com/pages/convert.htm

6nm is about 4.5 lb/ft.

Grumps
Thanks, I'm 99% sure I'm going to take it back.
 

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Discussion Starter · #5 ·
Ventruck said:
Click in the clamp or the wrench, or the bolt head?, etc

Sometimes it's a case where the non-threaded hole becomes a bit threaded by the screw, catching onto it, and then slips to then emit a clicking sound. My double bolt clamp does that sometimes and suggests 35nm.
The wrench clicked, not the clamp or the bolt.
 

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I don't own a torque wrench. I've never had a problem with my carbon bike. I have a friend who has carbon bars and he has to be careful when tightening his stem bolts or else he might crack his bars (so his LBS tells him). Or course I'm a little retro. I recently purchased my first ever work stand. Half the time I forget to use it..
 

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Get me to In&Out
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Sears has a decent wrench that only does inch pounds, but it is reverse marked with NM as well. I agree that 50nm seems very high for a seatpost binder bolt.
 

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Go to sears and get one of their small beam-type torque wrenches, the kind that have Nm and inch-pounds. It will probably have a 1/4 inch drive on it. You might have to get an adapter if your hex key sockets are 3/8.

Don't use a clicker unless it's very high quality and of a small enough scale so that the torques you're trying for are at least in the middle of its range.

Another thing to consider - go to your bike shop and get a "Ritchey Torque Key". It alone will safely take care of a large number of your common bike adjustments - seat post clamp and stems for instance.

Use carbon assembly paste on your post and you'll reduce the amount of torque needed and feel much safer. Also available at bike shop.

Finally - check that seat post clamp spec. Without going out to look at mine, I'd bet it's 1/10 of that. I do know that I use my Ritchey Torque Key on that bolt as well as the stem and it is about right. It's 5-6 nM
 

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I used a torque wrench to build my bike a couple of days ago. For me it was peace of mind and loved using it. Other than the pedals and cranks, most of the bolts were somewhere between 4 and 8 nm. So a seatclamp at 50nm?? Perhaps it meant 5.

But I swear by them.
 

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Yeah, just started using one

I bought in C40 in 2003 and didn't buy a torque wrench back then. I don't have a whole of of carbon fibre components so never a need. Last year I bought a used BMC SLC01 and somewhere along the line picked up a small torque wrench for bikes by BBB. So far only used it for the two bolt seat clamp on the BMC. My guess is that your seat bolt clamp is 5nm. On the BMC the top one is 5nm, bottom is 8nm. Procedure is tighten lower first, then upper, then lower again.
 

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spookyload said:
Sears has a decent wrench that only does inch pounds, but it is reverse marked with NM as well. I agree that 50nm seems very high for a seatpost binder bolt.
"Very high" is an understatement—50 Nm on that bolt will almost certainly break something. The very cause of the OP's problem may be the mislabeled (or misread) seat clamp rather than the tool he bought. Of course, it could also be just a typo in his post.
 

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metric (off topic)

Uncle Grumpy said:
Yes.

First suggestion is not aimed at you specifically. m/kg is metres kilograms. You may not have worked that out because your nation refuses to leap in the 1970s and adopt the metric system. So suggestion No.1 is adopt the metric system. :)

Suggestion No.2 is take the torque wrench back to the auto shop. Automotive torque wrenches are made for torquing down cylinder heads, not nipping up seatposts.

You need to get a bike specific torque wrench such as a Park, Pedros etc that are made to deal with the smaller torque settings.

This conversion calculator is really simple to use.

http://www.boltscience.com/pages/convert.htm

6nm is about 4.5 lb/ft.

Grumps
Few things have caused our nation to unite and rise up as our abhorrence of the metric system. Sure that was that fight with the Brits over that taxation without representation, thing and 9/11. But we really hate that metric system. Maybe because its French. I remember back as a kid when President Ford declared we were going metric you'd think we'd surrendered to the Soviet Union. That didn't last long. So, we're keeping our imperial units, our 120 volts AC power, and driving on the right side of the road. We are stubborn like that
 

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Discussion Starter · #14 ·
Thanks everybody. The wrench is going back tomorrow. I looked at Sears & none of the stores in the area have one. I couldn't find it in the catalog either. I haven't looked at their web site. I just ordered the Park beam wrench. It's less expensive than the one I got from Auto Zone. It looks to me like the beam type may be easier to read, too. I'll double check the marking on the seat post clamp and get back to you on that.
 

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DaveG said:
Few things have caused our nation to unite and rise up as our abhorrence of the metric system. Sure that was that fight with the Brits over that taxation without representation, thing and 9/11. But we really hate that metric system. Maybe because its French. I remember back as a kid when President Ford declared we were going metric you'd think we'd surrendered to the Soviet Union. That didn't last long. So, we're keeping our imperial units, our 120 volts AC power, and driving on the right side of the road. We are stubborn like that
I dunno, you Americans! Give you 25.4mm and you take 1600m. :)

Hmmm, sayings like that do sound better in imperial.

Grumps
 

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Mr. Versatile said:
Thanks everybody. The wrench is going back tomorrow. I looked at Sears & none of the stores in the area have one. I couldn't find it in the catalog either. I haven't looked at their web site. I just ordered the Park beam wrench. It's less expensive than the one I got from Auto Zone. It looks to me like the beam type may be easier to read, too. I'll double check the marking on the seat post clamp and get back to you on that.
Many bike shops will sell a bike oriented torque wrench like a PRO, Pedros or Park. I've got a PRO which comes with 14" drive bits that does most of what I need on the bike, save for the cassette and BB.
 

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n00bsauce
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#1 You don't need a torque wrench for things like seatpost clamps. Tighten it until it doesn't slip and that's tight enough.

#2 Reserve torque wrenches for things that really need them. Like crank arm bolts or maybe stem bolts, especially if carbon. (I know, your seat tube is carbon and maybe your seat post but my advice above still holds for seat post clamps).

#3 Auto parts stores are fine for torque wrenches. They have them in all the ranges (2) you need. Get one in inch pounds with metric (preferably nm, newton meters) too and one in foot pounds, but not a high range, probably the lowest foot pound they have.

#4 Get beam wrenches. Virtually all bike parts allow a range of torques (say, 4-7nm) so extreme accuracy is not necessary. It's easy to see if a beam wrench is out of spec. You can see if the needle is pointing to zero. If it's not you just bend it so it is and voila, it's calibrated. Clicker wrenches are always a mystery, you never know if they're calibrated and calibrating is a pain.

#5 Practice tightening parts to a specific torque so you know how it feels. For most parts you can then do it by feel. Also, with carbon tighten it just until it doesn't slip. Ride and check. If it's still tight, it's tight enough. Don't over tighten.
 
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