Let’s face it. The majority of middle-aged riders will typically use 52/36 or 53/38 road chainrings; not because it’s ideal ratio for them, but because there is peer pressure for riders on lunch rides, sportives, group rides etc to show up with a 53T chainring.
This tradition is a gift the professional riders in the peloton has continued to dictate current thinking where it is now the ‘norm’ and dictates the ratios offered on new bikes to non-professionals.
Most of us don’t have the training to develop the power and souplesse required to spin 52T and 53T chainrings effectively, and consistently – especially if you live in hilly or mountainous areas.
It could also be a reflection of “back in the day” era where most riders used 53T and it was a general norm. But most of us also tend to forget that back in the day the smallest “freewheel” cog was 13T as it was screwed onto the hub.
As a simple comparison 53/13T @90rpm gives 46.5km/h(29mph). It turns out it is actually slower by 3km/h(2mph) than 48/11T at the same cadence.
These same cyclists struggle on the climbs or have difficulty to keep good cadence on the flat when using close spaced 11-25(28) cassettes. This results further in low and inconsistent cadence, poor performance resulting in low self-esteem, not to mention the physical effects of over-gearing, such as knee pain.
As a manufacturer of chainrings absoluteBLACK receives requests and questions on daily basis for unusual chainring combinations such as; 52/32, 50/30, or 53/32T which are not going to work well due to component limitations (namely front derailleur) nor are good for keeping good cadence across both rings and minimize shifting.
The lack of easily available alternatives force riders to over gear for what they are capable of. It’s also very visible on amateur races like Le Etape du Tour, in France. Out of around 15,000 riders, more than 30% usually don’t finish, the last 20-30% walk at least some parts of steepest climbs and around half of the riders who actually finish have really low cadence on the last climb before the finish line.
absoluteBLACK set a challenge to themselves to change this perception – in the same way they have reintroduced Oval chainring concept few years ago.
absoluteBLACK are launching a range of ‘Sub Compact’ oval chainrings in 48/32 and 46/30T that can be mounted to any 4 bolt Shimano crank, including models like 9100, 8000, 9000, 6800 and lower groups. It gives virtually anyone a chance to adapt ones gearing to their abilities.
30 & 32T chainrings hugely improve the cadence and smoothness of pedal stroke while riding long/steep climbs, therefore have significant, positive impact on overall performance. While 46 or 48T still allow for a high gear output on daily and group rides. 48/11T @90rpm gives 50km/h (31mph) and 46/11T results in 47.6km/h(29.6mph). And @100rpm it is 5km/h faster. At absoluteBLACK we believe It’s more than needed for vast majority of riders who, like us, treat riding as pleasure and not as a job.
Such configuration of ‘Sub Compact’ chainrings was considered impossible to manufacture on regular 110/4bcd crank spider, because 32 or 30T chainring teeth lay below mounting hole circumference. Therefore, these sizes were not available in mainstream for years. However, thanks to absoluteBLACK patent pending “offset chainring” solution it now becomes a reality.
The small (inner) chainring was re-positioned closer to the frame by 2.5mm using small threaded tabs (a solution similar to the absoluteBLACK 30T 104bcd chainring). This allows the chain to freely clear the mounting tabs of the crank. To keep the same distance between chainrings, which is necessary for proper shifting, the big (outer) chainring was also moved by the same distance using special recesses around the mounting holes. All these offsets on both chainrings and the use of custom bolts makes it possible and also allows for easy assembly of the chainrings.
Important thing to notice is that this solution does not require any modification to the rest of the drivetrain. The solution also delivers an improved chainline for the gears riders use most frequently, hence they, theoretically, allow for the drivetrain to last longer.
Both 30&32T chainrings have threaded mounting tabs. The 30T requires two special M5 Ti bolts and two M7 aluminium bolts. While the 32T is fixed with four M7 bolts, same as the above. Both chainrings are fixed together just with the bolts from the front, hence it is possible to mount them without taking the crank off the bike.
Front Derailleur setup
48/32T chainrings require exactly same setup as regular compact chainrings. That is 1-1.5mm gap between tooth tip and derailleur cage. The only exception is the “L” bolt which has to be opened completely since chainrings are positioned closer to the frame.
46/30T is setup in almost the same way as the 48/32. However, as almost every frame manufacturer hasn’t predicted the use of a 46T chainring on road bikes, the front derailleur braze-on mount is generally positioned a little higher than is desirable. absoluteBLACK advises in this situation to set up the front derailleur as low as your braze-on slot allows you. This should leave about 5mm gap from the tooth tip to cage edge. 46T shifting ramps were specially designed to accommodate such distance thus front shifting remains crisp and quick.
Due to precise tolerances, clearances and special design of the chainrings absoluteBLACK only recommends using Dura-Ace CN-9000 or Sram Eagle 12spd chains. Both of these can be used in 10 or 11spd drivetrain and result in very quiet and precise running.
Chainrings are sold separately, but meant to be only used as combinations of 46/30 and 48/32T. No other chainring combination is possible due to specifics in the chainrings design.
Prices for the 46T / 48T are €105/95£/124$ and for the 30T / 32T 76€/67£/87.5$. Small chainrings include necessary bolts in the price.