I've ridden the L'Eroica California twice...the first time in 2017, where I did the "Heroic" course (on an '86 Bianchi Sport SX), followed up by the inaugural (in CA) Nova Eroica event (Coastal Course - done on my Stinner Aero Camino) in 2018.
One thing to remember about the L'Eroica event is that it's basically a "fashion gathering", so as long as the equipment you're using looks the part, you should be just fine...and it's not like there's any tech inspection or judging of the "authenticity" of the bikes (unless you enter your bike in the Concours D'Elegance judging, that is ;-), so some upgrades, especially to gearing, should be just OK. Heck, the organization even licences the name for manufacturers to use on BRAND NEW bikes that are allowed to be run, so IMHO, a bit of "correct looking" upgrades doesn't go against the spirit.
For example, on my '86 Bianchi, I use a newer Truvativ polished aluminum touring crank (Touro) which has compact chainrings (50/34). Totally looks the part. Also, since I didn't have a decent wheelset for that bike, I decided to build up a more modern set of 32 spoke, low profile wheels. Ended up with a polished aluminum hubset from Origin 8, H Plus Son TB14 rims, and silver Sapim CX-Ray spokes...shod with Specialized 26c Turbo Cottons. Again, totally "looks" the part. Since I had previously upgraded the original Shimano 6-speed SIS shifting to 8-speed Dura Ace, I threw on an 8 speed 13-30 cassette, which works fine with the DA derailleur with just a minor "B" screw adjustment. The 34-30 low gear was much appreciated on the Cypress Mt. and Santa Rita dirt road climbs.
BTW, I actually ran that same bike (with different pedals and wheels) in the 2016 Belgian Waffle Ride as well. I've often wondered if it's the only bike to have ever done both BWR and the classic L'Eroica ;-)
It's a fun event...and make sure you take your time at the rest stops. The food (especially for the classic event) is typically quite awesome.
http://bikeblather.blogspot.com/
One thing to remember about the L'Eroica event is that it's basically a "fashion gathering", so as long as the equipment you're using looks the part, you should be just fine...and it's not like there's any tech inspection or judging of the "authenticity" of the bikes (unless you enter your bike in the Concours D'Elegance judging, that is ;-), so some upgrades, especially to gearing, should be just OK. Heck, the organization even licences the name for manufacturers to use on BRAND NEW bikes that are allowed to be run, so IMHO, a bit of "correct looking" upgrades doesn't go against the spirit.
For example, on my '86 Bianchi, I use a newer Truvativ polished aluminum touring crank (Touro) which has compact chainrings (50/34). Totally looks the part. Also, since I didn't have a decent wheelset for that bike, I decided to build up a more modern set of 32 spoke, low profile wheels. Ended up with a polished aluminum hubset from Origin 8, H Plus Son TB14 rims, and silver Sapim CX-Ray spokes...shod with Specialized 26c Turbo Cottons. Again, totally "looks" the part. Since I had previously upgraded the original Shimano 6-speed SIS shifting to 8-speed Dura Ace, I threw on an 8 speed 13-30 cassette, which works fine with the DA derailleur with just a minor "B" screw adjustment. The 34-30 low gear was much appreciated on the Cypress Mt. and Santa Rita dirt road climbs.
BTW, I actually ran that same bike (with different pedals and wheels) in the 2016 Belgian Waffle Ride as well. I've often wondered if it's the only bike to have ever done both BWR and the classic L'Eroica ;-)
It's a fun event...and make sure you take your time at the rest stops. The food (especially for the classic event) is typically quite awesome.
http://bikeblather.blogspot.com/