Hello, first of all congratulations and all the best,
planning the ride involves many aspects 1. Are you using your own bike? or planning to rent?
2. How many of you are going to ride
3. What about your expertise in repairing the bike
4. How many days do you have?
5. What is your starting point? Delhi? Manali?
6. Which season you are targeting? If you can answer above questions half of the planning is done automatically.
I have done Delhi to Delhi 3200km ride with https://devilsonwheelz.com.
they are pretty decent, they will help you with most of the above questions. Now to tell you more based on my experience 1. No plan is perfect when you are riding in Himalaya, complete trip is based on the mother nature s mercy
2. Never forget to carry - Diamox, Garlic, Camphor, Loads of extra Socks.
3. Repeat the second - how many branded sets of clothes you Carry is not at all matter s, having dry pair of socks is the most important thing.
4. Riding gear, Helmate, sun glass, water bottle, and first aid kit are the next important things to carry
5. Which bike are you planning to take? light weight 150 cc bikes like FZ will have problem climbing uphill where as they will easily go through slush in zozilla, where as Royal Enfield s have exactly oposite problem where they will struggle in slush. So bikes like Avanger are the best suited. let me know if you need anything more.
Also read my blog to get an idea 😀
https://www.tripoto.com/trip/surviving-the-toughest-mountain-bike-ride-in-the-world-5c6ada1b8313b
It's Great to read that you are planning to ride for Leh/Ladakh and the frist thing you need to take a note that when will you ride?....I mean to say If you are planning to go there in this current month so, would request you to change your plan and go in the month of June to september as these are the months which is favourable for bike ride in that terrians. Because nowdays it's heavy snow fall there and roads are difficult to ride a bike as well as due to high alttitude in this cold winter there might be scarcity of Oxygen as well which leads to health issue.
Carry all essential bike gears and spare parts, don't take too much luggage, don't be so hard while driving and passing the distance, listen to your body always.
Take winter clothing with you, and trip a lot of water as near Sarchu oxygen level is very low, and take proper medicines with you, we faced a lot of problem from Sarchu till Pang.
Keep Diamox with you. Also, keep drinking water even if you don't feel like drinking. Keep first day for relaxing don't move much let your body acclimitize.