This post is is a combination review and hack. When I received Wickwerks’ RRc mountain bike chainrings to test, I mounted them up on my XX crankset on a Niner Jet9 RDO.
Problem was, the rings were their 40/26 combo, which was replacing SRAM’s standard 3:2 ratio’d 39/26. That one extra tooth increased the diameter just enough to brush the front derailleur cage, snagging it ever so slightly (but definitely noticeable). On standard round tube frames, you’d simply loosen the front derailleur clamp and cable, slide it up the seat tube a bit, and re-tighten and adjust and go for a ride.
With the Jet9 RDO (and any other frame with convoluted tube shapes or layouts) using a direct mount front derailleur and non-adjustable mounts, the solution required some hacking…
PRODUCT DETAILS & COMPARISON
The black rings are Wickwerks, the silver are SRAM’s XX rings. Above are the small (26T) rings, and below the large (40T and 39T respectively).
Wickwerks’ rings are machined from 7075 T6 alloy then hard anodized (more on that process here). The big rings then get a bit more machining, evident on the outer face. This set is the first gen, not the newer direct bolt rings at the link above, because they’re the largest I could get on the Niner and still have proper frame clearance.
If you’re wondering what’s meant by “direct bolt”, it means you don’t need the nuts shown at left, the bolts thread directly into the rings just like on stock XX rings. Our first install was met with failure because the longer nuts (center) were accidentally included. This prevented them from tightening down all the way. They sent the shorter, proper nuts quickly and it’s mounted up fine. These things still require a specialty tool and are a pain in the butt, we’ll be happy with both chainring size combos are available in direct bolt, but they get the job done.
In the top image, Wickwerks extensive ramping on the inside of the big ring is clearly visible. Lead engineer Eldon Goates says the rings are designed to shift quickly, but that you shouldn’t sissify your shifts (not his exact words). Shift like you mean it and you’ll be rewarded with quick, precise front shifting even under power. Yes, XX rings do the same, but if you’re need to replace them or just want a slightly larger big ring than what’s offered as a stock combo, these are a less expensive option. Retail for the pair is $129.50 for the 40/26 tested, and $132.50 for the 42/28.
Above, the Wickwerks rings and bolts come in at 72g, 24g and 19g. This is with the longer nuts, so maybe save a gram or two with the shorter ones.
For comparison, the SRAM XX rings and bolts are 68g, 25g and 15g. Weights are within a few grams of each other, and with the newer direct bolt set up, they should all but identical.
I don’t have a ton of miles on these yet, but first impressions are good. They’re being ridden with an XX front derailleur mated to the new X0 Grip Shift shifters with SRAM’s top-end 10-speed chain. Per Eldon’s suggestion, I give the Grip Shifts a manly twist and shifting in both directions is snappy and accurate. I stand up to hammer and shift from small to big. Snappy and accurate. I hit a climb and downshift late in the game. Yep, snappy and accurate. So far, so good…good enough to provide a basic recommendation for them. The black anodized coating hasn’t started to wear off the teeth yet, either. I’ll file a long term report later this year.
At top shows the front derailleur in it’s shiny factory fresh condition. The tips of the chainring teeth just barely tapped the lower edge of the cage, with the tallest of them catching just enough to cause problems, particularly at the back part of the cage where the fold is that sticks out.
Below that, the end result of my hack: a shorter outer cage plate to clear the larger chainring.
These are pre-hack. In the big ring (right), there are no issues. in the small ring, you can see where the teeth hit the cage (left).
It was a relatively easy fix. Remove the crankset, cover the chain and BB so you don’t get metal filings on them, then use a small file to grind down the cage. Wipe the cage and frame down with a damp cloth before removing the coverings, too.
All told, I only took approximately 1.5mm off the cage’s height. The 40T chainring now clears the cage (barely), and I don’t suspect shifting performance would change if I reverted back to the XX rings. On the trail, shifting is (yep) snappy and accurate and I’m theoretically able to be about 2.5% faster now. Theoretically. I’ve probably also voided the warranty on the front derailleur.