Joerg wrote:
On 2018-11-23 09:48, wrote:
On Friday, November 23, 2018 at 9:29:33 AM UTC-8, 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.

-- Regards, Joerg

http://www.analogconsultants.com/

Joerg - in my experience this is because the rear derailleur is ever
so slightly out of alignment. If it is towards the higher cog it will
often "hop" and towards the lower side it will growl. This sort of
misalignment general is only 1/8ith or less of a turn of the rear
cable adjuster.


I have friction shifters and tried all sorts of fine adjustments. The
growl is independent of it.


You can also have a problem with a 7 speed chain on your reduced
cassette. While 7 and 8 speed gears have the same spacing between
cogs and the same cog width, some manufacturers are using 10 speed
components supposedly with wider spacers that may be not wide enough
for 10 speed cogs.


Ok, but it doesn't rub against a neighboring cog which is about the only
thing that could happen with a chain that is too wide. The growl even
happens when on the largest cogs an in perfect aligment.


Worn front chainring disagreeing with your new chain, perhaps?