Detailed description below, of one of my 2 favourite (and almost identical - see my Absolute Black video too : • Sub compact (46-30, or... ) set ups, in the quest to find the perfect gearing for both the uphill and the downhill here in the French Alps. You are unlikely to need such a huge range away from the mountains, although it would be great for touring. It's always better to have more gears than you need, rather than less !
This set up has a super wide 715% gearing ratio range !
The easiest / lowest gear ratio of 30-42 is the equivalent of a compact set up of 34-48 and will allow high cadence riding on 10% plus climbs (eg 9kph / 5.5mph at 95rpm on a 10% slope). The hardest / highest gear ratio is the equivalent of 56-11 which means you can still pedal comfortably at over 60kph / 40mph.
I have now (3/2022) been using this this set up for a whole year, without any issues. Shifting and pedalling was extremely smooth and quiet (noisy in video as filmed in a closed room) in almost all gear combinations.
I ride up to 200,000 vertical metres each year and have a number of top ten times on Strava for my age group on famous climbs out here , eg Col de l'Iseran (1st place). I have used a 10/42 cassette with a 50/33 crankset/chainset for the past 2 years on my Trek Emonda. I intend using the set up in this video (detail below), or similar, for some of the steeper climbs out here, eg Colle San Carlo (10km at a constant 10%) and Col de la Loze.. Knowing me, I'll probably just use it for everything though !
DESCRIPTION OF THE SET UP IN THIS VIDEO :
HUB must be Sram XD/XDR compatible. XDR (11/12 speed) replacement hubs are available for most, but not all, wheel brands.
CASSETTE is a 9/42 11 speed by ZTTO (Chinese). Quality seems generally good but I had to straighten up the 3 biggest sprockets as they were slightly warped (I used a wide bladed cold chisel that fitted snugly between the sprockets). E-thirteen and Leonardi offer higher end / more expensive versions, but I have not tried either yet.
I fitted a 2,5mm spacer behind the cassette to help the chain-line. This was the thickest possible for my wheel.
CHAIN is a 12 speed Sram Eagle GX. This 12 speed chain significantly improves shifting compared to Shimano or Sram 11 speed chains for some reason.
CRANKSET/CHAINSET is a Shimano GRX 46-30, which is a straight swop with Shimano road ones. Note that GRX chainsets push the chain-line out 2,5mm compared to standard Shimano Road chainsets. This is a disadvantage as it creates more chain angle to the bigger sprockets. Back-pedalling when in the 2 biggest sprockets will cause the chain to drop. However, it does not noticeably affect normal pedalling performance :0) .
I am waiting on a pair of 46/30 AbsoluteBlack chainrings for Shimano road chainsets that actually bring the chain-line 2,5mm in, which should be a great advantage (5mm difference compared to this set up). My slight concern is that the AbsoluteBlack chainrings are only available in oval form. Previous trials with bigger 50/34 Osymetric chainrings on a Dura Ace chainset in combination with a 10/42 cassette were not successful as the chain fell off the 2 biggest sprockets when pedalling normally. I will post a video with the AB 46/30 ones if they prove successful.
Di2 ULTEGRA rd-r8050GS medium cage rear derailleur (or Dura Ace r9150 if you fit a GS cage) with a Wolftooth Roadlink DM hanger extender. A hanger extender is essential with these 2 medium cage derailleur options (max official capacity w/o extender = 34). Di2 is a huge advantage as it effectively eliminates chain slack - the default setting prevents selection of the 2 smallest sprockets when in the small front chainring. Chain slack (I forgot to fully trim the B screw for this video) is likely to be an issue with a mechanical groupset, although I have not tried it yet..
I have refitted the derailleur return spring to the second of the 2 holes so that it is stiffer.
Note that earlier GS (medium cage) Di2 derailleurs have shorter cages/lower capacity and so a 40 cassette is probably as big as you can go.
FRONT DERAILLEUR : standard Ultegra r8050 Di2 lowered as far as possible. Bigger gap than recommended but works fine. Guess a GRX mech would allow exact spacing. Sideways adjustment not an issue with the Ultegra mech.
In summary:
46-9 gear combination is harder/faster to pedal than 50-10
30-42 allows climbing 10% gradients at 9kph for a cadence of 100 (à la Froome)
Enjoy !!
More soon..
Негізгі бет GEARING FOR STEEP CLIMBS, LONG HILLS, BIKEPACKING & DOWNHILL : Ultra wide range : 9/42 + sub compact
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