Re: Had a wtf? this morning - Ping AMuzi

On 2/23/2025 9:40 AM, Roger Merriman wrote:

Shadow <Sh@dow.br> wrote:

On 22 Feb 2025 22:21:58 GMT, Roger Merriman <roger@sarlet.com> wrote:
>

Shadow <Sh@dow.br> wrote:

Went out for my morning ride. Just before a rather steep hill changed
down and I heard a clump and the chain jammed.
>
I looked back and half of my rear derailleur was sitting on the
asphalt.
>
OMG, I thought to myself, this is almost as embarrassing as a crank
arm falling off. Then faced the "walk of shame" home.
>
Note, I scrub chain/jockey wheels/sprockets with water and detergent
every 200 Km. Was almost due for a new clean. Gear change was
absolutely smooth until the incident. HI and LOW screws perfect, no
way the chain came off and "fell into the spokes".
>
Note I managed to rip a spoke clear out of the wheel with the
breakage. What fell into the spokes was half the derailleur. I suppose
that'll mean a new wheel too
>
:(
>
<https://www.sendspace.com/filegroup/v/qdHDWfYEJvo99L3/MhFp6hhZL5Z8ugxHfSuN/uTo4>
>
The "cleaned" in the filename is because I cleaned the EXIF metadata,
not the parts after the incident....
>
So "wtf" happened, what did I do wrong and how can I prevent it from
happening again?
>
TIA

>
Did the derailleur come apart due to impact with wheel/cassette or a
failure and then do so?
>
My old commute bike, had a rear mech fail where the cage and parallel meet
apparently was glued in place? Was an Alivio so broadly similar to the
Tourney I think from memory, Cues which I replaced it with is substantially
more heavily built like the MTB mech’s as to if it will last any longer?
>
The Alivio lasted 9 years and 19,000 miles so probably got my moneys worth!
>
Mind talking of Andrew I expressed surprise that front mech’s could wear
though! My Gravel bike front mech (Sora) had to be replaced due to that!
Only just shy of 12,000 and 7ish years old so definitely sub par, though
have replaced like with like and didn’t really seem any reason to match the
rest of the bike ie GRX mostly with Tiagra shifters.
>
Okay (at least in uk) neither of Tourney/Alivio/Sora/Cues are particularly
expensive being £30ish for a derailleur.
>
Roger Merriman

>
Thanks for the reply. The gear had around 8000 Km on it, and I
replaced the jockey wheels last year the cogs were looking like spikes
they were so worn.
I have no idea what caused the breakage. There was a lot of
debris on the road, but I was only doing around 15Km/h, possible but
not likely I managed to pick up a twig and it flew into the spokes.
It felt like it just decided to break..... I would have
expected it to show some signs of failure beforehand.
The bike has 8 gears at the back. The derailleur that broke
was a RD-TX35, designed for 7 gears. Maybe that forced it.

 As long as the shifters have same pull, derailleurs are speed agnostic to
the best of my knowledge, see chain rings as well for most part at least.
 On the whole even what are budget group-sets should soak up lots of miles,
I had Tourney on the CX bike I owned few years back, was essentially a
proto Gravel bike as a number of CX bikes at the time, ie never intended to
be raced but to hack around the woods and what not!
 Had 3/7 Tourney
<https://bike.shimano.com/products/components/pdp.P-RD-A070.html>
 Looks to be more budget than yours and much less teeth capacity, it’s
gearing range and gaps were somewhat annoying. But it certainly worked
fine, I didn’t like the Tourney shifters much with the thumb shifters.
 

I can get a Shimano Tourney TY300 cheap, around US$ 15, or an
Altus RD-M310L for around US$ 35. (since salaries, pensions etc in
Brasil are roughly 1/10 of British, multiply by 10 to get an idea of
relative prices).
>

The Altus as far as I can see, no clutch etc would considering the price
difference particularly including the multiplication would appear to offer
little value over the Tourney.
 More modern Altus rear mech’s do have some more features or as and when
Cues reaches you and the cost is appropriate sure yes potentially worth the
upgrade.
 

PS I have no idea if it's short, long, over under etc. I have
the only Shimano gear in town. Nothing to compare it to. People here
use "Sunrun" and "Yamada" which sell for around US$ 4.
[]'s

How cross compatible are they? None of the above mech’s are particularly
sophisticated though should be durable enough, ie they don’t have some of
the MTB technology such as Clutch and so on, they are “just” a rear mech.
 Kinda depends if “Sunrun/Yamada” are made from cheese and disintegrated
upon use?
 Roger Merriman
 

Shimano has used the 'Tourney' model name for many products since around 1974.  The current version TY300 is only wide range ("SGS") and has three different mounting options.
https://bike.shimano.com/products/components/pdp.P-RD-TY300-SGS.html
Shimano says "6 or 7 speed compatible" but they will shift both older four or five systems as well as 8 speed rears. Not enough lateral travel for more sprockets.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971