Fouriers 42 Cog & Chainring

Fouriers is another brand offering parts to assist with single ring drivetrain conversions. We checked out their CR-DX003 chainring ($87 with alloy bolts included), as well as the range expanding CR-DX004 rear cog ($99).

The rear cog is offered in two sizes; 40 or 42 tooth and a range of colours; green, red, black and blue. We tested the 42 tooth version; it’s a universal add-on that slips in behind a 10-speed SRAM or Shimano 11-36 cassette. To make room you need to remove a cog and one spacer from lower down the cassette. We chose to remove both the 15 and 19 cogs, replacing them with a spare 16 cog that I had in my parts collection.

As with any of these add-on big cogs, you need to readjust the derailleur’s B-tension screw to gain sufficient clearance on the big cog. With a bit of tinkering I had my SRAM X.9 derailleur shifting through the wider 11-42 gear range. Going from the 36 up to the 42 was smooth enough but – as always with these conversions – there’s an overall degradation in the shift quality. Everything still works but the shifting loses a bit of precision; it probably won’t bother you unless you’re fussy about the shift quality. If you feel the shift quality will be a concern, opt for the 40T cog. You’ll still gain a lower gear but it’ll keep the derailleur closer to the cassette and the shifting will be more consistent as a result.

At 66g the Fouriers 42 cog is pretty light. The 40 and 42 cogs offered by most other manufacturers are between eight and 13g heavier. In comparison to the two other wide-range cogs that I had on hand, the Fouriers had more side-to-side flex. While this didn’t affect the shift accuracy, I did manage to bend the 42 cog with a bodged gear change under load whilst struggling uphill. It’s hard to say if this would have occurred with another brand but perhaps a heavier/stiffer cog would have coped better. In any case it wasn’t too hard to straighten and I’m still using it now.

By comparison, I couldn’t fault the CR-DX003 chainring. Like most aftermarket 1X chainrings it uses tall teeth and an alternating wide/narrow profile to enhance chain retention. It’s offered in two tooth jumps from 30 to 36T and a range of anodised colours. Ours featured their ‘Ti Rainbow’ colouring—while it looks a bit wild at first, it blends well once on the bike.

The tooth profile is excellent and offers chain retention that’s as good or better than the offerings from the more established MTB brands. It’s made from 7075-T651 alloy and their Ti finish appears to offer added durability. After four months of regular use, I wiped the chainring clean and found that the coating was still intact—better than I’d expect with a regular hard anodised finish. Definitely a first rate product.

Falco Bike Australia (02) 9584 8450 / www.fouriers-bike.com