A new style of derailleur hanger alignment tool by Wolf Tooth

[Samuel D]

The device in question.

Jim Langley, technical editor at Road Bike Rider, thinks this is the best invention since sliced bread. He describes it in this video. Skip the first 5 minutes if you know how traditional tools like the Park Tool DAG-2.2 work.

I can see the appeal. Alongside quick and intuitive operation, the tool weighs 175 g (quick-release version) and packs small. Langley also makes claims for its accuracy.

I haven’t found an EU source yet, but some German shops stock Wolf Tooth parts so I’m sure it will come.

[Brucey]

it seems like a posher variant on the old 'pull the QR skewer out the right side and use it as a gauge whilst using an allen key to tweak the derailleur in situ' approach. A flaw with this arrangement is that if there is no QR tension whilst the alignment is being set and the dropouts themselves are not perfectly aligned, they will move a bit as the QR is retightened.

One also has to be a bit concerned if the thing is strong enough to use on a steel frame too.

But then it presumably isn't meant for anything as old fashioned as I'd choose to use...

cheers

[gxaustin]

Is it safe to start levering the mech hanger attached to a carbon bike? Are the carbon drop outs/stays designed to be stressed in this way?

[tony_mm]

Definitely a good tool.
But I would be cautious concerning its accuracy.

[DaveReading]

Definitely a good tool.
But I would be cautious concerning its accuracy.

I'd have though accuracy was a prerequisite for describing something as a good tool ?

[Samuel D]

The accuracy may be deceptive. There are many potential sources of error with a Park Tool DAG-2.2 when you’re sliding its gauge bar in two dimensions to clear obstacles while rotating the tool around its axis that is off-set from the wheel’s axis.

The eye is adept at detecting parallelism, so the Wolf Tooth method has the potential to yield higher accuracy than you might imagine from its short dimensions. There is no pivot slop because there is no pivot. There is no slop in any gauge bars because there are none. There is nothing to knock by accident to ruin the measurement or your confidence in it. The wheel need not be true or the user aware of the need to rotate the wheel to account for lack of truth, because the rim is not used as a reference point.

The Wolf Tooth relies on the face of the drop-out being flat and square to the wheel axle, but those seem to be reasonable assumptions in this context.

Langley, who has used all of these tools and seems competent to judge, claims the Wolf Tooth has better real-world accuracy than the others.

Meanwhile, how much accuracy do we really need here? It seems to me the Wolf Tooth offers a small, light, quick-to-use, confidence-inspiring method of aligning the hanger with adequate accuracy at a slightly lower cost ($60 for the quick-release version) than most alternatives. Perhaps Langley overstates its significance at the beginning of his video, but that adds up to a useful invention in my books.

[Brucey]

The accuracy may be deceptive. There are many potential sources of error with a Park Tool DAG-2.2 when you’re sliding its gauge bar in two dimensions to clear obstacles while rotating the tool around its axis that is off-set from the wheel’s axis...

the park tool isn't perfect by any means. But it does allow the alignment to be checked with the wheel in place and with the QR tight. If you want super-accuracy you can use a Vernier caliper to measure between the arm and the wheel rim (this is what I do). This should easily get you to a small fraction of one degree accuracy.

The park tool design also is man enough to bend a strong steel gear hanger if needs be, and whilst the threaded part might eventually get damaged, it can be replaced. I've replaced mine with a part that I can renew ad infinitum, and is (unlike the original) adjustable for its clearance in the housing, and (again unlike the original) doesn't load the threads in the hanger.

The wolf tooth tool can be carried on the trail, but in that case you are mainly interesting in getting home, and anyway 'perfect alignment' is hardly ever the requirement once the mech has been into the wheel or has hit the ground. Its also often the case that the dropout itself is no longer in perfect alignment following an 'incident'. For trail use you would be better off just carrying an adjustable spanner (or long allen key) and tweaking the hanger until the (probably bent) RD lines up well enough to continue the ride, pending a proper repair.

As a workshop tool I doubt that the wolf tooth tool is strong or durable enough to see hard service, and if the QR pressure is not applied as the alignment is checked, it won't be accurate whether sighting in the way envisaged is really inherently precise or not.

So I might be wrong but for now my best guess is that this tool is neither fish nor fowl. TBH I'm not sure how much better off you are than if you just screw an M10x1 threaded axle into the hanger and use that.

cheers

[Samuel D]

[…] if the QR pressure is not applied as the alignment is checked, it won't be accurate whether sighting in the way envisaged is really inherently precise or not.

Why can’t the quick-release be tightened as usual? That is how I understood it to work. The sighting rod screws onto the 5 mm skewer.

TBH I'm not sure how much better off you are than if you just screw an M10x1 threaded axle into the hanger and use that.

That gives you something (short) to grab but nothing to sight against (and nothing to support the hanger unless you add bits and pieces, admittedly easy to do). Humans, especially well-practiced ones, are amazingly good at detecting even perpendicular alignment errors, but there are several visual traps around the hanger that make alignment difficult if you don’t have something parallel to sight against.

I live in a shoebox and my main interest in small tools is to literally have space to store them. I wouldn’t want to carry this Wolf Tool around on tour since, as you mention, there are other ways of getting the hanger adequately straight without a dedicated tool. But its smallness, neatness, and simplicity of operation appeal to me.

Although much is talked about accuracy I haven’t seen much need for extreme accuracy here. Sure, if the hanger bends even slightly it may throw off the indexing, but that is a separate problem from the bent hanger itself – even if caused by it. That is, you can tweak the indexing to solve that (at least in the short term). Of course I run 8-speed that is less sensitive to this stuff than the latest Campagnolo experiment. Certainly my derailleur has more clearance from the spokes.

[Brucey]

I understand the desire for compact tools but if you use conventional QRs then all you need to do exactly the same job is a length of M5 studding + a few nuts and washers to make a sighting tool (which replaces the QR skewer temporarily), in addition to the spare axle.

FWIW I let a chum have a used mech but it appeared to be bent when it was fitted to his bike. "This mech is no good ?" he said. Turned out that the old mech was only roughly straight on the bike because the hanger had been tweaked to allow for the (already well out of line) rear mech. Once the hanger was properly aligned (super accurately) the alignment of my RD was near-perfect after all. I've since built a tool for checking/resetting RDs so that there is no doubt about which part might be bent.

FWIW the original shimano specification for the hanger alignment was 0 degrees, minus nothing + 0.5 degrees, so that small 'toe out' and 'negative camber' was allowed/preferred. With a conventional tool this tolerance can be measured exactly and worked with. With the wolftooth tool it can't.

cheers

[Samuel D]

FWIW the original shimano specification for the hanger alignment was 0 degrees, minus nothing + 0.5 degrees, so that small 'toe out' and 'negative camber' was allowed/preferred. With a conventional tool this tolerance can be measured exactly and worked with. With the wolftooth tool it can't.

Good point, though the trig to do that is forgotten by most people who muck around with bikes.

[Brucey]

I think what usually happens with the usual tool is that it isn't ever 'perfect' and instead of endless pointless adjustments (which may themselves cause fatigue damage...) towards an unattainable goal, an experienced mechanic will be happy as soon as it is within the tolerance band, i.e. within a couple of mm in the correct direction.


BTW it occurs to me that if the wolftooth pointer screws onto the existing QR skewer, this will ensure that the hanger is aligned with the outer face of the dropout. This ought to be aligned with everything else of course, but it often isn't; witness the number of QR skewers you see with a small 'set' in them, because they have been used on imperfect dropouts.

cheers