lineinthewater

Could someone give me a ballpark on appropriate torque for the clamp bolts on an aluminum stem, going on a aluminum steerer? I've searched, and best I can come up with is 8 Nm. Does this sound accurate?

DaveSSS 

If the stem has two M5 bolts (takes a 4mm hex wrench), limit the torque to 5Nm. Personally, I've never used a torque wrench for any M5 bolt. If you can't put the bike together without one, how do you expect to make any adjustments, out on the road?

lineinthewater

6mm hex (width of tool head). I'm using this opportunity (putting my entire bike back together) to get a feel for the proper torque specs throughout the bike. That way, if I need to work on it in the field, I know roughly the proper torque (feel) to apply (without a torque wrench).

dsbrantjr

"If you can't put the bike together without one, how do you expect to make any adjustments, out on the road?"

If the OP has a torque wrench, why not use it? Field expedients are fine but it doesn't make sense to me to guess when you can measure.

I'd also recommend lightly greasing the bolts to avoid them seizing due to corrosion. I use and recommend Tef-Gel.

lineinthewater

Thanks, I did grease them before installing.

I measured the actual thread diameter, and it's also 6mm.

FBinNY 

There's another way to approach torque on things like stem clamps. That's to focus on the end result. You want the stem tight, and if you approach it by degrees and test from time to time with the old fashioned "hold wheel between knees and twist bars" test, you'll find the leas stressed setting that does the job.

If you're like me, you don't actually want it super tight, but what we used to call race tight or crash tight. That's tight enough to control steering reliably, which requires very little torque, yet loose enough to slip and twist in a crash. That can go a long way to mitigating damage like bent bars, twisted forks, or bent front wheels.

BTW- I'm not a fan of aluminum fasteners, finding them a bit too unreliable. Also on many parts designed around steel fasteners aluminum ones of the same size often aren't strong enough to do the job.

HillRider

I don't think the bolts are aluminum, only the stem itself and the steerer.

To the OP: the Forte (Performance's house brand) stem I have specifies 8 N-m for both the steerer and handlebar clamp bolts. I has a 2-bolt stem clamp and a 4-bolt faceplate, all M5 bolts. I assume that's for aluminum or steel steerers and aluminum bars. I limit the steerer bolts to 3 to 4 N-m for my carbon steerer and about 5 - 6 N-m for the aluminum bar clamp.

FBinNY 

Your right, I misread the OP. But it doesn't change the intent of the first part of my post. The right torque is the lowest torque that does the job. This can be determined either from a specific torque spec, based on the fastener itself, or by function based on the end result.

Since you know what needs to be done, it's easy enough to approach it that way. Tightening fasteners tighter than necessary just because you can, makes no sense.

Andrew R Stewart 

FB- +1.

Many people think that the torque setting on the component is the only level that's correct. Like some people think the labled air pressure on a tire is what it needs to be. The labled numbers are max levels. If a lower level works well then the component will lat longer, being under less stress. Andy.

lineinthewater

I appreciate your approach ... but I honestly wouldn't know how hard to stress/twist the handlebar to simulate a realistic MAX riding load. I don't want to overtorque, that's for sure, but for this specific application I'd rather be slightly over (optimal) and 100% secure, than slightly under. I'm sure your hands/instincts are far better tuned than mine, so keep that in mind.

lineinthewater

Yes, this stem is very similar to Forte's. For now, I tightened to 7 Nm, based on all the comments here and other reading. I'll keep an eye on the thread and adjust if necessary.

FBinNY 

There's plenty of latitude. Steering torque is tiny, think about how hard you work when riding. It's almost impossible to have a bar so loose hat it'll move in normal riding, so that's not the issue. Instead it's a balance based on convenience. You don't want the bar always moving when the bike is jostled or bumped into. OTOH, slippage in a real crash is desirable. So use your judgement to find something in between that you can live with.

In other words, without assigning a number value, you want it firm, but not rock tight. My front wheel and fork flex somewhat as I twist the bars, then they slip.

lineinthewater

Thanks for your comments. When you crash, does your bike split into perfectly undamaged pieces? lol

While I have your attention, any suggestions for torque values on a Cannondale Fire carbon seatpost, both at the rails, and at the seat clamp? I'm unclear if the portion of the seatpost that attaches to the seat rails is carbon or aluminum. It sure would be nice that if you buy a bike new, they give you a complete listing of all torque values.

fietsbob

Stripping out the aluminum from overdoing it is more of an issue.. the bolts that grasp the steerer tube only have to
A) hold the headset adjustment, sufficiently. and B) turn the wheel, while riding..
have you Emailed the brand's HQ, and asked them?

lineinthewater

It's a Cannondale. I've emailed them on other issues in the past, and I didn't even receive a response. Maybe I was just unlucky - don't know.

fietsbob

Ask your Retail dealer that sold the bike?

there are torque charts for Mechanics , but the use of steel threaded will accept more torque , than aluminum.

Cannondale buys stems, they don't make them, so the stem company is another authority.

in the LBS we have a preset torque driver , it goes click when there.

uses a Torx bit when doing up brake discs.

Looigi

One thing I do with seat post clamps and the like that have be tightened with a torque wrench is to loosen them an exact number of turns and then tighten them to the same place. Another is to first loosen it a half turn then tighten it the same amount to calibrate yourself to the correct torque, then proceed with the adjustment.

Kimmo 

FB's advice is good, but sometimes headset adjustment doesn't stay put unless you clamp the stem on the steerer pretty hard.

On my bike with a textured ally steerer and two bolts that take a 5mm key, I find I have to crank em up to about 3/4 of the most I'd ever want to put into em to maintain headset preload.