Sunday, 14 April 2019

Old Man Gears for an Old Man?

new bling - a Shimano HG-500-10 cassette is now on my bike

Since I went for super-short cranks, I have had a bit of a hill problem.
My 175mm cranks had a triple ring setup, and I used to run 48, 34, 26, along with my 11-32 SRAM PG850 cassette.

The 145mm cranks I switched to (MUCH easier on my ageing right knee) are only a "double) at 48, 34.

So my "crawling up a hill" gearing had gone from 26f/32r (= 0.8125) to 34f/32r (= 1.0625) - a rise in gearing of 30%

Hmm, I thought to myself.
I have friction shifters (so I don't have to worry about indexing), and a "long-cage" derailleur (a Shimano RD-591), so, maybe I just need a new cassette and chain, give everything else a clean up, fiddle with the b-screw, reset the High and Low stops on the derailleur, and job done?

Sort of ;-)

I went with a Shimano HG500 cassette in the new 11-42 size that they now offer, with an SRAM 1051 chain. I was very pleased with the SRAM 850 chain I used for a several years (when I bought Hoppy, it had an OEM KMC chain, and it seemed a pity not to just use it!), so, I thought to myself, a SRAM 1050-ish series chain will do me fine.
New bike bling for old folks? - Shimano's new-ish 11-42 10-speed cassette, and a new, shiny, so shiny, chain
So ... got to get the old stuff off ...
setting up a comfortable work area - the deck chair is essential ;-)
The back of the car has a flat load area, so it also make a comfortable area to sit,
as well as a place to lay out tools etc.

The OEM KMC chain doesn't have a "quick link", so time to get out the chain splitter
(Park Tool mini-splitter shown).
With an 8-speed chain (shown), the pins are reusable,
so just push the pin out far enough to get the chain apart.
Don't push the pin right out as it makes it MUCH harder to rejoin the chain later!

Cranks gotta come off, for a clean up as much as for anything else.
Also my 34t sprocket is a plain steel "reversible" piece, and is showing a bit of wear,
so now is also a good time to "flip" the sprocket
so the new chain drives the "unused" side of the sprocket teeth.
New chains on worn teeth are a good way to get fast chain wear!

which sprocket remover to use?
the silver one is a "cheap" one, the black one is a Park Tools FR-5.
Both fit a modern "Shimano"-style Freehub.

I used the "cheap" one, as it has a 1/2" drive socket,
so I can use a nice long tool to get the cassette lockring off.

A great thing about the SRAM PG850 cassette is that the sprockets are held together
with a very thin hex bolt, not a rivet,  so ...

... undo the hex bolt, and ...

... the sprockets and spacers all come apart.
Make cleaning a LOT easier, as well as potentially allowing easy
"mix and match" gear ratios, combining the most useful from a couple of different cassettes.

A magnetic tray is handy for small bits (in this case the long, thin, hex bolt from the cassette)

The "working parts" of the RD591 derailleur come apart reasonably easily for cleaning

The 10-speed HG500 cassette goes on nicely to replace the 8-speed PG850 cassette

The crank all cleaned up. These are "Stronglight" branded.

Yep, these really are 145mm extra-short cranks.
tbh, they look like they are cut down from a Stronglight 175mm crank
(and, yes, I do have a Stronglight 175 for comparison)

Problems selecting the lower (bigger sprocket) gears ...

I replaced the b-screw (original is the black one)
with a longer one

Still not enough, so I chucked a couple of nuts on the b-screw
 to further space it out from the derailleur stop
what about the indexing?
I have "old school" friction shifters, so there is no indexing.
You just gotta learn (and feel/hear) where the correct shifter position is.
Remember, folks used to win the TdF with friction shifters if you go back to when I was a lad!

1051 chain is 114 links - looks a bit short in the 37t rear gear (34t chainring)

Yep, I need more chain links than the 114 that came in the packet.
Chain shown on the 42t rear sprocket and the 34t front chainring).
A few links will be explained by the frame size - I have an XL frame.
(the OEM chain, fitted with 14-28 gearing and an OEM 28/38/48 chainset, had 116 links!).
So, until I get a longer chain, it is "small ring only" for me!

Still got a few niggles to work out, but the 11-42 setup as shown has already completed a 60 mile ride across the Chilterns, With a 13% hill at this end (Aston Hill), and a 14% hill at the far point of the ride (Rectory Hill, Amersham), I was sure glad of the lower gear ratio that the 11-42 provides.
(ride is on Strava here:

So how low did I go?
34f/42r = a gear ratio of 0.81, pretty similar to the 26f/32r ratio I had before (0.8125)

Thus a "double" 34/48 with an 11-42 cassette has a similar overall gear range to a "triple" 26/34/48 with an 11-32 cassette.
As will be easily deduced from a Google search, there are a LOT more "double" chainsets than "triples", and in a LOT more variations, makes, and quality grades, too!

So there we have it.
an 8-speed steel 34t chainring driving a 10-speed chain, driving a 10-speed 11-42 derailleur, shifted by a 9-speed long-cage derailleur with a modified b-screw.

Just gotta sort out that chain length now!


  1. Nice write up PP, I had no idea you could use a 42 tooth rear sprocket with a normal rear mech. I looked at a wide range 10 before I splurged on my alfine, but wasn't sure whether my rear mech would take it, only short cage though.

  2. another "bodge" that folks do is fit a "drop link" to lower the derailleur. Sunracee (iirc) do a well-priced one, and other brands are available, too. Dunno about short cage, but some folks use them with medium cage derailleurs.
    an alternative would be the special 3-speed rear hub that takes a 10-speed sprocket on it (Sunrace iirc), but with your super long chain length, you will still get a lot of chain "slap", i suspect.