How wide are the Kysirum SL's?
I ride Enve 3.4s or 6.7s as race wheels, and specifically looked for a wide rim when it came to training wheels. The Zipp 101s have fit the bill nicely. They really ride well and are decently aero. I'm only 170 pounds and not particularly tough on equipment, but I went ahead and had mine built 20/24 on Alchemy ELF hubs. Super bombproof build. Rode them recently on about 11 miles of rocky, rutted-out fire road when the local group ride decided to go "LA Roubaix" style: No issues.
Why match wide racing wheels with wide training wheels? Because I can very easily swap brake pads (from carbon to aluminum compounds) and not even have to adjust the calipers when making the swap. Sure you could adjust cable tension to adjust to a narrow training rim, but then there is a good chance that your brake pad won't get good contact with the narrow rim, since it will have worn in at an angle suited for the wide rim. Keeping rim width relatively equal solves this (I'm assuming your 404s are FC and not the older, narrower rims).
So I would probably go with the 101s.
Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099
I ride Enve 3.4s or 6.7s as race wheels, and specifically looked for a wide rim when it came to training wheels. The Zipp 101s have fit the bill nicely. They really ride well and are decently aero. I'm only 170 pounds and not particularly tough on equipment, but I went ahead and had mine built 20/24 on Alchemy ELF hubs. Super bombproof build. Rode them recently on about 11 miles of rocky, rutted-out fire road when the local group ride decided to go "LA Roubaix" style: No issues.
Why match wide racing wheels with wide training wheels? Because I can very easily swap brake pads (from carbon to aluminum compounds) and not even have to adjust the calipers when making the swap. Sure you could adjust cable tension to adjust to a narrow training rim, but then there is a good chance that your brake pad won't get good contact with the narrow rim, since it will have worn in at an angle suited for the wide rim. Keeping rim width relatively equal solves this (I'm assuming your 404s are FC and not the older, narrower rims).
So I would probably go with the 101s.
Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099