Technical FAQ: Combining eTap AXS MTB and road components; tire balm

The new SRAM eTap AXS groups allow riders to mix and match components to get wider gearing. Plus, Lennard explains how to preserve tires that aren't seeing much use.

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Dear Lennard,
I want to set up my 1X gravel bike with bigger tires and lower gears. Can I use those Force eTap AXS levers with an Eagle AXS rear derailleur and cassette?
— James

Dear James,
Yes, Force and Red eTap AXS levers will work with Eagle AXS rear derailleurs; SRAM calls that a “mullet” build — road controls, Eagle AXS rear derailleur, and a 10-50T cassette.

Due to the larger rollers on the SRAM road 12-speed Flattop chains, you have to use an Eagle Flattop MTB chain with the Eagle (or other SRAM 12-speed MTB) cassette. You can, however, use a Force or Red AXS crank with it. When I asked if the smaller Eagle chain rollers create premature chainring wear on the road AXS chainrings made for the bigger road AXS chain rollers (seems to me that the rollers would sit toward the front of each tooth valley), SRAM engineer Brad Menna replied, “No. We tested the configurations in our labs. The Eagle chain meshes with the Road 12sp CR teeth adequately enough to provide the same performance and retention functionality. There is no loss in durability. You can use either a 1X RED or Force AXS 12sp crank or an Eagle crank — frame chain-line will determine which crank to use.”

The Force levers have one port for a Blip; the Red levers allow two Blips (or Clics) to be plugged into each lever. Unless you’re running aero bars or sprint shifters on your gravel bike along with bar-top climbing shifters, the Force levers should suffice.
― Lennard

Dear Lennard,
In a previous article, you recommended spraying cyclocross tires with 303 Protectant. I did this with my cargo bike tire sets — studded winter and rest-of-year (Marathon Plus) tires and have been very happy with the results.

Would you recommend the same for road tires? Road tires have a much smaller contact patch and therefore may be more sensitive to any reduction in grip. It sounds like you have a lot of experience applying 303 so I thought I’d check before I treat my own tires.

Yes, the real solution is to simply ride the tires until worn through but sometimes life gets in the way and the tires start to degrade due to age.
— Matt

Dear Matt,
Yes, I use 303 Protectant on my road tires during storage. I am quite certain that it prolongs their life, and I have never noticed a reduction in grip with them. I have a lot of bikes, and, as you say, life gets in the way of wearing out the tires on them. On the bike that I use all of the time, I generally don’t use 303, because the continuous working of the tire keeps the antiozonants in the rubber compound active at the surface, and I wear the tires out before the slower process of oxidation degrades them.

Tensile stress (i.e., tension) on the tire during storage allows cracks due to ozone, oxidation or UV attack to propagate rapidly. Tensile stress on the rubber compound increases if the bike sits on a flat tire, causing sharp folds along the edge in a localized area; high air pressure in the tire also increases tension on the tread rubber. Without tensile stress, the cleaving of molecular bonds in the rubber compound caused by ozone, oxidation or UV attack stays close to the surface (in the case of ozone attack, it is confined to the top 20 microns of the rubber; slower-acting oxidation penetrates deeper). If the rubber compound is under tension, however, microscopic cracks can open in the surface where the molecular bonds have broken in the compound, allowing the ozone, oxygen, or UV light to attack the surfaces inside the crack, which causes the crack to open further under tension, exposing more surface to attack, and so on, ultimately resulting in deep cracks.
― Lennard

Dear Lennard,
I would like to install a Leonardi cassette 9-36T 11-speed on my road bike with mechanical Sram Red 22 speed. I have an 11-36 cassette (PG 1170) and works well with WiFli long cage.

What I would like to do is to transform my Fuji SL 1.1 in a 1×11 with 36 or 38 single chainring. This would only be to save weight.

I think that without the 50-tooth chairing, front derailleur and cable, I can save approximately 200 grams. Actually, my Fuji with Spada Spillo wheels weighs only 5kg without pedals. Is it possible in your opinion?
— Pietro

Dear Pietro,
You must have a SRAM XD driver to use with that Leonardi cassette ; you cannot install it on a standard road freehub. I don’t see an XD freehub option with the Spada Spillo wheels. If you end up having to get a heavier wheelset than those 820-gram Spada wheels in order to get an XD freehub body to fit that cassette, you could easily end up adding back that 200 grams you were trying to save. You’d better check with Spada about an XD driver option.
― Lennard