Commuting by bike

Perhaps an E-bike would be a good choice? Faster than pure pedal and can be fitted with good lighting, also because they are less effort you tend to sweat less.

Winter tyres are available with studs for ice if its frosty.

Have you got a bike already do you do any cycling ?

I commute 9km each way - I bought an ebike as it is hilly and this allows me to avoid changing at work - I commute in a shirt and cycling jacket, and keep a few work jackets and spare pair of shoes in my office.

For 15km - I would recommend doing the same unless it is very flat (or windy and exposed). This is less important if you plan to shower and change at work.

Make sure you have a bike that takes wider tires, full mudguards and a rack to attach a panier bag. Get two lights too - I prefer to have one pair on the bike (either dynamo or ebike) and a second that I can charge via usb. If you are travelling on unlit roads you will need stronger lights.

Other than that I would suggest having a back up plan for the days you don't want to cycle - I can take the car or public transport. Both of these are slower and much less pleasant, but there is the odd day (particularly rainy ones) where I just don't feel like taking the bike.

Forgot to ask what bike do you have ?

22km door to door, Maynooth to Parkwest and back home again in the evening. PreCovid I was doing it 5 days a week in all weather. I'm fortunate that there are showers and some limited clothes storage at work. I also work in IT so don't require a shirt and tie just need to be respectable! I did it on a Hybrid first a couple of days a week as I'd never ridden a "road" bike but it was a bit slow and difficult to filter through traffic, I then bought a second-hand cyclocross bike and used it for 2 years up to Covid.

The frame snapped on an outing during covid and I picked up a nearly new gravel bike and for the first time clipless pedals(Ignore the name your feet are stuck to the pedals). It had 650b wheels which are too much for my commute so I swapped these to 700c x28 with schwalbe puncture-resistant tyres. I can do the commute in 45mins on a good day but usually takes me about 50.

My route involves a mix of canal towpath depending on the route its 6-9km and the rest is a mix of urban and rural roads with no lighting. The lack of lighting has never bothered me but I have good lights and 2 of each at the front and rear in case one dies/fails.

In the bag, I carry the day's clothes and spare cycling top I can handle the shorts being wet but if the top gets soaked it's miserable. I have reasonably good wet gear but its rare I'd need it and the days you do it would be difficult for anything to keep you dry! I also carry a spare tube, puncture repair kit, CO2 inflator, mini pump and a multitool for any repairs needed. That said in all my time commuting I've only had half a dozen punctures, a couple of cables snap and one chain failure but that's several 1000kms of commuting.

I've come off twice in ice so now with WFH I'll definitely not risk it anymore but unless it was very wet the night before even on very cold mornings it's not that much of an issue.

I hadn't cycled since college when I started 5 years ago and just slowly built up to it. 15km is very achievable with just a moderate level of fitness. I'd recommend trying it on a day off just to get to know the timing and route and don't be afraid to get out google maps and look for alternatives to any pinch points or roads you don't like! I take a slightly longer route and cut through some housing estates to avoid a couple of narrow fast roads on my commute there's no shame in it :)