On 2018-11-23 17:22, John B Slocomb wrote:
On Fri, 23 Nov 2018 16:37:07 -0800, Joerg
wrote:

On 2018-11-23 15:09, John B Slocomb wrote:
On Fri, 23 Nov 2018 09:29:58 -0800, Joerg
wrote:

On 2018-11-23 08:07, Sir Ridesalot wrote:
On Friday, November 23, 2018 at 10:59:18 AM UTC-5, Joerg wrote:
On 2018-11-22 20:59, John B Slocomb wrote:
On Thu, 22 Nov 2018 16:05:54 -0800, Joerg
wrote:

After installing a new Sunrace 40-11T cassette (minus one cog),
a new chain and a new rear derailer the road bike can now climb
hills much better. 40T as biggest cog versus 32T before.
Woohoo!

However, on the middle and three larger cogs (it's now a
7-speed) there is a distinct vrrrt .. vrrrt sound when under
heavy load. Maybe from the chain because with a derailer setup
it'll never run 100% straight. Hard to say. The noise appears
briefly twice per pedal crank rotation and always on the power
strokes.

The chain is a KMC Z50 that should be suited for 7-speed and I
looked, it doesn't rub against a neighbor cog. Maybe a "teeth
exit grinding"? On the 3rd cog from the largest it's really
weird because that has an almost perfect chain line when on the
small chain ring up front.

Anyone heard that before? Can it simply be ignored? Or maybe
it'll go away over time?

I've had a noise from a front derailer due to the chain rubbing
on the derailer "cage".


It's definitely not that. The chain visibly doesn't rub anywhere.

-- Regards, Joerg

http://www.analogconsultants.com/

You've checked that whilst riding? I find it interesting that the
noise ONLY happens on the power stroke.


While slowly riding up a hill under high power and then again with
applied brakes leaning against a wall. However, on Sunday I'll have a
friend take a close look while doing that.

What's really weird is that it also emits this noise while on the
largest 40T cog where it doesn't have a chance to rub against anything
in the cassette. I can clearly see that it doesn't rub at the front
derailer. My guess is that it is some sort to "teeth disengangement" sound.

Another thing I found out is that one has to carefully and somewhat
slowly shift onto the largest cog, else the chain flies over it and into
the spokes. That is no problem though because I'll only use that on
really steep hills. For most hills the (for me new) 36T will suffice.
When I service this next time maybe I'll take the cogs off, make an
aluminum protector disc, drill it and the 40T cog and mount that towards
the spoke side. Should catch the chain.

That chain slipping off the large cog is often due to the derailer
stop setting. Try, with the bike either hung from a bike maintenance
stand or set bottom side up, setting the stop screw so it won't shift
onto the large cod and then adjusting it say a quarter of a turn at a
time until it will just shift.


I've tried that. If I set the top idler much closer than 1/4" to the 40T
cog shifting becomes laborious. VRRR .. RAT TAT TAT TRRRT KA-CLOCK.
Sounds awful. Until I can make that next cassette mod I'll just have to
shift back down to the first gear slowly.


The chain coming off the large cog and going into the spokes is not a
good thing as it tends to damage the spokes, particularly when it
comes off under load, and you may have a series of drive side spoke
breakage... how do I know all this? Because my chain came off under
load :-)


I had that happen on the MTB a lot (Dore XT indexed Shifters). There the
main casue was rock hits. Rocks keep flying into the works all the time
and then one bends the derailer hanger, and off the chain goes at the
base of the next steep hill.


Back in the day, some bikes had a plastic plate mounted between the
cassette and the wheel to protect the spokes.


That was a very good thing. I wonder why that is no longer done. Hey, I
can make one from Perspex, with embedded flashing blue LEDs :-)

I'd guess that it isn't used today as the pseudo racers thought it
looked "dorkie" and removed them before they took the bike out of the
shop.


Yeah, they also think side reflectors are dorky. That's how I almost hit
a cyclist at night. He blew a stop sign, was on a dark frame, dark
clothes. IOW he was nuts.

--
Regards, Joerg

http://www.analogconsultants.com/