During the winter months I use my road bike on my trainer. I have a fan and have the setup near a window for decent cooling but I still sweat more then I do on my outside rides. I cover the bike with a towel to protect the bike from sweat but still notice damp spots and drops on the bike from time to time.
I have begun cleaning the bike with a damp cloth after each use and sometimes rubbing alcohol.
What would you recommend?
I would at least spray it down with water once or week or so to make sure your dissolving away all that salt. I think something as simple as just spraying it down with a water bottle or two of water would be enough.
Another option is to use “cockpit wipes” like Armorall wipes to give a bit more thorough wipe down.
And change your handlebar tape, that stuff gets nasty.
Using neat IPA might eventually start to degrade the clearcoat - don’t hold me to that though.
To be honest, I’m pretty sure DCRainmaker touched on this having never used anything to protect a bike nor experienced any issues as a result.
If you were concerned though then I’d use a synthetic sealant that you would on a car (or a natural wax - just it’s more time consuming to apply). A synthetic sealant (AutoGlym Extra Gloss Protection for example) is just a case of wiping on, leaving to dry and then buffing off.
Water & sweat should bead off and in the general course of cleaning & drying it’ll be quicker too. It feels super slippery too not to mention makes it shiny & glossy 
I’m a bike mechanic and from my experience I’d say PLEASE PLEASE PLEASE wipe your bike down and give it a proper clean every now and then. If your bike sits on the turbo all winter, then perhaps every 6 weeks just loosen your stem bolts and take your headset apart, give it a clean and regrease, and put it back together. Or use a proper sweatguard.
I’ve had to declare forks as a write off due to the effects of salt damage around the steerer tubes, and when you have to use a mallet to remove a fork from a frame because its so well stuck in there, it’s not very pleasant.
I guess it depends on your personal sweat/salt content, but it can get real nasty in there!
I have a bunch of hand towels that I use for each ride. I fold one over the handlebars during the ride. Sweat runs down my arms and onto the towel mostly and I can use the towel to wipe my face when needed. This catches 90% of the sweat I would guess, the rest drips on the floor or on the top tube. After the ride, I use the towel just to give the seat, top tube and handlebars a quick wipe. Every 2 weeks I’ll give the bike a proper wash.
Baby wipes.
I have a matte finish carbon frame and use baby wipes, as necessary. Otherwise, just a dry towel while whispering sweet nothings to Baby 
I have a Canyon with one of the Arcos headsets with an hole where the stem cap should be. I dread to think what the inside of my forks look like now.
+1 Baby wipes. Just make sure when you buy the massive bulk pack, you get the NON-SCENTED ones!
Also, if you want to make the clearcoat look nice & shiny before any event, a small spray of WD40 onto paper towel and wipe the frame all over - gives it a nice showroom condition shine.
Make sure you don’t get it on your brake track/discs/pads though!
I have a dedicated trainer bike based on a steel frame from the late '70s, so I am concerned about this. I have a spray bottle of camellia oil, which is used by Japanese woodworkers to prevent rust on their cutting tools. I know the bike shop uses Boesheild T9 to clean bikes.
WD-40 should be used with caution on certain plastics. At my company we use it to get the machines shiny for trade shows (I’m not inte cycling industry). After a few trade shows the plastic will be really brittle.
Edit: I don’t know which plastics are typically used on bikes/bike parts. WD-40 is hydrocarbon based and is destructive to PC and PS in particular. These are cheap materials and I doubt that they are used widely on bikes. But it’s something to be aware of.
minimalist does have a point here.
Personally, I looked up automotive clearcoats and the general consensus I could find from ‘the internet’ (code: not actual paint experts) was that it was fine. On that basis, I did a spot trial and have now been doing it for about 5-6 years on both my current frame and my previous frame - with no apparent ill effects.
Also, I don’t do it that frequently - only a couple of times a month. The amount that goes on is also VERY minimal… it’s not like I spray the whole bike with the stuff then wipe it down. Literally, a small spray on a square of paper towel will do the whole bike.
However, i’m no paint/clearcoat expert. As the TR crew would say, ‘this is just my experience’.
Funny I was thinking the same thing this eve on my Canyon
Not sure if other folk have already said but a simple set of head and wrist sweat bands work wonders
I wheel mine outside every few days and give it a 10 second spray with the hose.
I was going to say the same thing. Good Ol’ 1980’s style sweatbands reduced the amount of sweat reaching the bike by probably 80% or more. Most notably sweat coming from my head. Plus they are dirt cheap on amazon and tons of colors to choose from.
Baby wipes after every ride, especially the seat. And then a more thorough clean after completing each plan.
And I Pledge my bike. Lemon fresh hmmmmm
Just don’t sweat, problem solved 
