WGB 

I haven't had a bolt work itself loose in awhile so maybe I am tightening them correctly but I can certainly see the need for a torque wrench. Minimal cost and something close to certainty each time you tighten a bolt that it's neither too tight or too loose.

Problem is a) what size do I need for general bike repair?

Some small kits are 1/4in drive and run from 2-14 Nm which should fit most applications but for some pedals/crank arms/cassettes you need to get up to 50 Nm.
Will a cheap hobby kit from eBay work "well enough"? Do I need two torque wrenches (light duty, say 2-14 Nm and heavy duty 15-100 Nm?

b) Do brands really matter? Again, will a cheap hobby kit from eBay work "well enough"?

dsbrantjr

I may catch a lot of flak for saying so, but I have had very satisfactory results with Harbor Freight "click" type torque wrenches in 1/4". 3/8" and 1/2" drive. They are not as pretty as my decades-old (pre-K-Mart) Craftsman ones and the setting lock is clunky, but they have checked out fine on the torque calibrator at work. The ones I have click in both directions, necessary for pedals and most bottom bracket installations; not all do.
I try not to use any of them on the lower 20% or so of their full-scale range as accuracy suffers there.
Keep in mind that bike component torque specs are often +/-10% or even 20% so extreme accuracy is not required. We are not building jet engines or spacecraft.

sdmc530

I am actually with @dsbrantjr I have a Pittsburg tool torque wrench from HF that I use on the higher torque numbers like the bb and such. I do have a bike hand NM torque wrench, I think it maxes out a 30nm or something for more delicate stuff. The NF freight one was under $20, the bike hand one that is probably better quality was $50ish from my LBS. Both have served me well.

FiftySix

I have an old deflection beam Craftsman inch pound/newton meters torque wrench that I bought new in the late 1980s. Still works great in both directions and being able to see the torque increase before a "click" is nice too. Seems to work decent at low ranges, but the 5nm for some bolts is really too low to be in range unless you get a low range torque wrench.

The design has been copied by many since the 1980s, and this one at Park Tool is exactly like my Craftsman in every detail except for the branding. https://www.parktool.com/product/torque-wrench-tw-2

While the deflection beam isn't versatile in blind situations like a click type is, it works great on bicycles and motorcycles. I can't think of a time working on a bicycle that I couldn't look directly at the torque wrench to read the scale.

Here's a modern version. 3/8" drive newton meters and inch pounds. https://www.arestool.com/70213-3-8-i...-torque-wrench

Just to add another link - https://www.parktool.com/blog/repair...s-and-concepts

But in reality, I don't really use a torque wrench on the low end bicycles I have. For small fasteners that say 5nm, I use two fingers placed near the bolt head for less leverage on a hex wrench, and on the higher rated torques I use all the leverage a wrench provides and put more effort into it. Not recommended, but I turn wrenches for a living on machines that come with no torque standards and you get used to feeling what amount of force will strip a particular bolt or nut that goes into a particular material.

If you're worried about fasteners coming loose while riding, blue Loctite is your friend.

easyupbug 

While I agree with dsbrantjr the key is he calibrates. It is easy to do, check out you tube videos. HF is hit and miss on these things, my neighbor brought one to me as he was suspicious and it was way off. Took it back and the manager said wait for his next batch to come in and exchange as the current batch on the shelves (still) were all off.

fietsbob

Id say 1/4", spend up on that one , 3/8" & 1/2" a good quality beam wrench should be fine.

davidad

https://www.homedepot.com/p/Presa-1-...4BUw&gclsrc=ds

Get a 1/4 and 3/8 to take care of everything on a bike. They are accurate in inexpensive.

Kevin R

Hi

Having gone the carbon fiber route, i started to use a torque wrench.

I have been using the PRO Shimano torque wrench (good for 3 - 15 Nm) with confidence of my carbon parts.

For the crankset, pedals, and cassette i have found a hex wrench to be adequate.....never had parts run loose.

wipekitty

This little guy has done just fine for light duty use on my carbon fiber bike, and it's cheap: https://www.amazon.com/Venzo-2-10NM-...dp/B00V4CQEGW/

It's also small enough to fit in a seat pack, just in case you ever feel like torquing in the wild.

FiftySix

I've never seen one that small before. Too cool.

squirtdad

I use the park adjustable driver for the small stuff (I have that venzo mini beam also)

and a craftsman beam for big stuff

works for me

ThermionicScott 

I use a $20 Sears/Craftsman beam-type. Does everything I need.

canklecat

I was about to order a portable clicky doodad preset torque wrench in the 3-5 nm range, but that Venzo is so cute I might order it instead. Never saw such a dinky beam wrench before.

FWIW, I bought a Venzo tool kit after resuming cycling in 2015 I needed some tools -- I'd sold everything after my neck and back were broken in a 2001 car wreck, so I figured I'd never ride bikes or need tools again. It's been a good kit, no problems with any tools. And some are really good, like the shop grade chain tool included with the kit. Venzo doesn't offer that particular kit anymore, a shame because it was better than most starter kits. So their teensy torque wrench is a safe bet.

Racing Dan

Even if you get cheap kit, its vastly better than guessing and plenty accurate enough. Just get what you can afford. Id argue a 3-15nm or there about is all you need. It takes a real ham fist to overdo the cassette, pedals or BB.

Marcus_Ti

I'd be less worried about overdoing them than underdoing them....30Nm-50Nm on, for example, crank set fasteners is more torque than most people would blind-feel, and for single-bolt designs that can lead to dangerous hilarity.

easyupbug 

It was not really what I would call hilarity but shock, I was on my baby at the time, a brand spanking new Campagnolo state of the art 50/34 arm careening down the asphalt, I felt horrible.

Wilmingtech

For precise torque in and around carbon steerer, smaller torque values in the 2nm - 8nm range I use a digital Wheeler Fat Wrench.

For values in a larger range 10nm+ I have no problems using a cheap harbor freight click type torque wrench. Just make sure you keep it calibrated.

cpach

If you want to get a smaller torque wrench that only goes up to 14ish NM you can supplement it with a large beam wrench. At home I do this with an Effetto Mariposa wrench and a large park Beam wrench, although there's an annoying set of torques around 16nm that are common for suspension pivot bolts that the beam wrench isn't ideal for. Given the option and a relative lack of concern over budget I really liked the Topeak digital wrench I used at my last shop.

If you do a lot of work the little t handle wrenches are really nice time savers--Park and Prestacycle both make some nice ones with adjustable torque now. These are mostly for pinch bolts and such.

San Rensho 

Agree 100%. The only thing I would add is to make sure that all the fasteners are very clean and lightly oiled. I've never had a fastener strip or come loose using a torque wrench and clean fasteners.

Drew Eckhardt 

One with a maximum setting of 15-20 Nm, which will be accurate torquing fasteners to 3 or 4 Nm limit respectively. You can't count on torque wrenches being accurate below 20% of their full scale reading, and wouldn't want to use a 2-20 Nm wrench for less than 4 Nm.

I like 1/4" hex drive. It will fit in more places a 1/4" square drive ratchet plus bit sockets don't, and quality hex bits (I like Wiha) cost much less than good bit sockets. You can also get an adapter which mates 1/4" hex bits to a 1/4" square drive ratchet.

One with a maximum setting of 75-100 NM, not exceeding 5X the limit of your small wrench. It should be usable in both directions for bottom bracket cups and pedals.

3/8" square drive is more common on bicycle specific sockets like those for bottom bracket shells, although I have a cassette lockring tool that's 1/2". Expect to occasionally need an adapter.

My 4-20 Nm and 6-50 Nm get the most use on bike parts, although the 20-100 is needed for the highest torques. Lots of people destroy crank arms they fail to tighten sufficiently without using a torque wrench, and I wonder how much of the aluminum Shimano splined freehub dent problem comes from too little torque.

I haven't needed my smallest 17.5 - 87.5 inch-lb (2-10 Nm) and largest 40-200 Nm wrenches for bicycles.

Park has a table of common and uncommon bicycle part torques: https://www.parktool.com/blog/repair...s-and-concepts

The calibration matters.

Nice ones come calibrated from the factory.

When yours doesn't, you should lock its drive in a vise and hang weights off it to see where it clicks. Torque is the product of weight and the distance from the center of the drive it's applied.