DIY Derailer Alignment

Kyle.B.H said:

My wife likes to fall over on her bike, while standing still, to the right,
landing on the rear derailer. While I do replace the hanger whenever it
gets bent, I'd still like to check the derailer alignment wrt the rear wheel
and/or frame. The Park DAG-1 is 50 beans, so I'm wondering if anyone has
had any luck with building their own?

I figure all I need is the appropriate sized bolt and some nuts for the
derailer hanger end, attached to a hefty piece of straight wood. Then I can
just use a ruler to measure from the rim to the wood. Sound reasonable?

Thx,

Kyle

You don't need a tool: reverse the rearwheel (cogs left) and fit the
frontwheel to the dropout (remove the skewersprings, and you might need
a 12mm nut as a thick washer to clear the other skewer) It's now easy to
see if the wheels are parallel

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Quoted message said:

You don't need a tool: reverse the rearwheel (cogs left) and fit the
frontwheel to the dropout (remove the skewersprings, and you might need
a 12mm nut as a thick washer to clear the other skewer) It's now easy to
see if the wheels are parallel

How would that help? I think the poster is wondering about his wife's
derailleur hanger alignment, not the wheel alignment.

The DAG is an oft-used tool in my experience. I've never had to replace a
hanger as a result.

--
Phil, Squid-in-Training

Kyle.B.H said:

My wife likes to fall over on her bike, while standing still, to the right,
landing on the rear derailer. While I do replace the hanger whenever it
gets bent, I'd still like to check the derailer alignment wrt the rear wheel
and/or frame. The Park DAG-1 is 50 beans, so I'm wondering if anyone has
had any luck with building their own?

I figure all I need is the appropriate sized bolt and some nuts for the
derailer hanger end, attached to a hefty piece of straight wood. Then I can
just use a ruler to measure from the rim to the wood. Sound reasonable?

Thx,

Kyle

I've done this before. I used a long bolt screwed into the
hanger threads and locked it in with a nut. Then I placed a
small carpenters square along the bolt and a ruler placed at
right angles to measure from the square to various points
around the wheel. The long bolt can then be pulled to
bend the derailleur hanger until all points measured are equal.

deray alignment is tricky(artful as in F1 design by garage floor
chalkmarks) without the gauge. AMuzi tells me the gauge is one step of
a sequence of adjustments leading to the exactness apparently required
of index shifting-like something found in a modern repair shop for
computer cars.

the chalkmark method requires eyesight plus mental equations of
distance and geometry: as in when the cog and CR faces disappear
together then those pieces line up-then eyesight need to follow that
postion to the other parts to see what their doing from the intial
cog=cr position.

try a sting. a string from the down tube then lead alongside the seat
tube and carried back to the dropouts then sighted gives an indication
of what happened to the dropouts when garanny ran over the frame and
may give some visual acuity or orientation for the following.

one give away is the chain links enetering and leaving the bottom
pulley wheel on the way to(sight)the CR. Which way does the chain bend
as it leaves the pulley to the desired cr.Pick the cog=CR combo that
annoys.the chain shud be straight. try not to bend the hanger the
wrong way. think about the motor movements a few times then look
between your legs while upside down thewn go with the tool and bend.

That's an adjustment now done with a LARGE channellocks with a LONG
handle or a LARGE vise grip, bending the hanger to straighten the
chain as seen at the pulley. grab the deray/hanger bolt inboard and
outboard sides.

(g.daniels) said:

deray alignment is tricky(artful as in F1 design by garage floor
chalkmarks) without the gauge. AMuzi tells me the gauge is one step of
a sequence of adjustments leading to the exactness apparently required
of index shifting-like something found in a modern repair shop for
computer cars.

I've got the tool at home but a couple months ago while travelling
fixed a friends bike with a 12" adjustable wrench and a lot of care
and luck.

JT

John Forrest Tomlinson said:

(g.daniels) said:

deray alignment is tricky(artful as in F1 design by garage floor
chalkmarks) without the gauge. AMuzi tells me the gauge is one step of
a sequence of adjustments leading to the exactness apparently required
of index shifting-like something found in a modern repair shop for
computer cars.

I've got the tool at home but a couple months ago while travelling
fixed a friends bike with a 12" adjustable wrench and a lot of care
and luck.

JT

That is how I fixed my bent deraileur after a crash. Big ol "
crescent wrench and tweeked it back . Works flawlessly.

right! when eyeball lining the cr/gearcluster cog so the surfaces
disappear, the pulley cage's sides will then flatten out inperspective
and also isappear!and at that point(hehehe), the cage shud be directly
under the selected gear cluster gog and perfectly vertically aligned
with that cog.
it's like learning to read print instead of clouds,tea leaves...