Singletrackmind
Well-known member
Do you have any information on how e*thirteen Helix Race e*spec Chainrings perform in conjunction with SRAM AXS T-TYPE Transmission drivetrain?
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E*thirteen Helix Race e*spec Chainring Performance
- Thread starter Singletrackmind
- Start date
Given your SRAM AXS T-Type setup on the Wild, the ethirteen Helix Race espec is one of the more popular chainring choices for exactly this combination. The short answer is yes, they play nicely together, but the details matter.
The Helix Race espec is designed for eMTB use with a direct mount interface for Bosch (55mm chainline for the Boost version), and the T-Type flat-top chain is the variable to watch here. The chainring needs to be T-Type compatible to work properly with the flat-top chain profile. The good news is the Helix Race espec is indeed listed as T-Type compatible, so you're not forcing a square peg into a round hole.
On the practical side, @Stihldog has been running a SRAM AXS derailleur with an ethirteen chainring for four years - fast, smooth, quiet, no drama. That's on a non-T-Type setup, but it speaks to the brand compatibility generally. More relevant to your specific Bosch Gen 5 situation: there's a community note worth flagging that SRAM XX Eagle Transmission chainrings have separate part numbers for Bosch Gen 4 versus Gen 5, despite sharing the same 55mm chainline and mounting. Worth confirming whether the same applies to the ethirteen range before ordering, as the Gen 5 Race motor on your Wild may have slightly different interface geometry.
One installation tip from @Th3bill that's worth not ignoring: set cage lock to position 1 before tensioning the chain on a T-Type setup. Forgetting that causes chain contact on the smallest cog, which is the kind of thing that's infuriating to diagnose after the fact.
I've got data on chain length calculations for T-Type and chainring sizing comparisons if that's useful - you were asking about 34T vs 36T earlier today so I'll leave that to you.
Singletrackmind
Well-known member
- Thread starter
- #3
Please provide the data on chain length calculations.
Right, chain length for T-Type. I covered the headline in the 34T vs 36T thread earlier today, but here's the full working so you can calculate for your specific setup.
The SRAM method for T-Type is slightly different from the old "biggest-to-biggest plus two links" approach. For T-Type you size the chain using the largest cog only, bypassing the chainring entirely in the initial calculation. Route the chain through the derailleur and over the largest cog (not through the front chainring), then add enough length so the two ends meet with one inner and one outer link overlapping. That gives you your base length, then you add two links. That's your starting point.
For a 34T chainring versus 36T, the difference works out to roughly two links (approximately 25.4mm). The geometry of the rear triangle doesn't change, so it's purely the chainring circumference adding chain demand. On your Wild with the T-Type rear mech, going from 34T to 36T means adding those two links, otherwise the derailleur cage runs out of travel on the lower end and you'll get chain slap or binding under load.
One thing worth knowing with T-Type specifically: the cage lock mechanism I mentioned from @Th3bill's tip (position 1 before tensioning) becomes even more critical when you're dialling in a longer chain, because the cage travel range is calibrated assuming correct initial tension. Get that wrong and your chain length calculation ends up measuring against a misconfigured baseline, which is a special kind of frustrating to diagnose after the fact.
For your 100kg riding weight, I'd err toward the slightly longer calculation if you're between link counts. T-Type under load from a heavier rider can expose marginal chain length issues that lighter riders never notice.