wayold

My wife an I are heading off for a long trip around Europe starting next month. Not explicitly a cycling trip so we aren't bringing bikes, but we do expect to rent bikes for several days in each of several different countries. I'll be bringing my helmet, bike computer, small multi-tool and some bike clothing (shorts, jersey, shell, gloves), but I'm wondering if I need to bring anything else. My wife thinks we should bring lights (front and rear), but I think local lighting regulations might vary enough that we should get whatever lighting we might need from whoever is renting us the bikes (in particular I think the 3000 lumen death beams I favor in the US may be illegal in some countries). Things like a Garmin radar (which I really like on US roads) may be irrelevant in Europe. I don't want to bring the kitchen sink with me if I can avoid it, but are there any must haves I'm leaving out?

cyclezen

You're not giving much info. E-Bike or std pedal bike - 'road'/performance type or 'town' type bike?
Which countries? Rural or urban? All 'daylight' or some 'night' (lighting for 'visibilty' or for real darkness riding)?
Will you be wishing to ride 'clipless' pedals if so, shoes, and maybe pedals also.
Spending time and money shopping for stuff or just gonna wing it?
That said, Quite a few of the Large chains will also have a basic selection of cycling stuff, like floor and frame pumps, helmets, basic tools, basic bike bags... but not always everything in each store...
I can say for certain that both Aldi and especially Lidl have assortments of bike stuff in many/most of their stores - there are other chain stores as well.
Being old school, I do like real maps for places I'm new to - there are cycling specific maps (routes and bike paths marked) . Most tourist Info offices/stations might have area cycling info. Certainly many bookstores often have extensive map resources for much of Europe... also true for hiking oriented maps.
Ride On
Yuri

50PlusCycling

If I am going to spend a lot of time on an unfamiliar bike, I will bring a broken-in saddle from one of my bikes, and a pair of shoes and pedals. A pocket tool is a necessity, as I will probably have to make minor adjustments for comfort as I get used to the bike. Lights which are small, rechargeable, and clip or strap on are a great idea, most rental bikes don’t have dynamo lights. A must-have is rain gear. When I bring rain gear, it never rains, if I forget to bring rain gear, it will rain every day.

indyfabz

You’re going to install and remove a computer every time you rent a bike? Pack zip ties and any necessary tools.

As noted, saddle, pedals and shoes. They are the important interfaces.

wayold

I thought about bringing all my preferred contact points (saddle, grips, pedals) along, but I thought for a few hundred miles scattered over a few weeks I could ride whatever they give me. These will be flat pedal touring type bikes so pedals/shoes will be non-critical in any case. Saddle is a consideration, though. I've rented bikes with some godawful ass-hatchets installed when traveling in the past, but I figured we could buy something serviceable in any decent bike shop if necessary.

Mounting a bike computer (or lights, or a saddle for that matter) just takes a couple of minutes with an Allen wrench. The multi-tool I'm bringing has a set.

The point on rain gear is totally valid. I was just going to go with a waterproof shell, but at my wife's insistence am packing a poncho too. Living in California I don't do much riding in the wet, but in a European autumn it seems very probable I will do a fair bit.