From your first post I assumed that you wanted to leave from Dali Old Town (FYI: Xiaguan is called Dali as well but is something completely different then Dali Old Town some 15 Km north of it. Generally speaking with Dali we mean Dali Old town.)
There is a special cycling route around the lake that is used by hundreds of tourist daily who use bikes or e-bikes. Anyway it is a good way to check if you have adapted to the altitude because it is at an altitude of about 2000 meters. The round trip is about 80 Km and mostly flat but surprisingly many don’t make it around (Including lots on e-bikes because their batteries have gone flat).

I would do Dali to Shaxi in two days.
Dali to Yangbi is about 55 Km and you drop about 500 meters so easy going but you need good brakes. Yangbi has some gems like the old chain bridge and Chinese mosque.
Yangbi to Shaxi is about 110 Km and a nice cycling road.
(The only other place to stop overnight is Liantiexiang some 62 Km from Yangbi)

From Shaxi you can make day trips to Shibaoshan National Park and you can try to cycle to Maping.

From Yangbi you can cycle west via Taipingxiang to Beidouxiang. This is the old Burma Road and the dirt/cobblestone road has been upgraded recently (Some cobble stone and dirt stretches are still there). This is a really nice road and has historical significance. In Beidou there is a small guesthouse in the middle of the village but is hard to find.

Cycling to the TLG and Lijiang you have to take the big provincial roads and they are horrible to cycle. Anyway both places are terrible tourist traps which I usually avoid. A better option is taking a bus to the TLG area and walk the trail instead (See elsewhere on this forum)

You refer to China Eastern Airlines while the letter above is from Eastern airlines. Clearly not the same.
Looks like a scam to me..........

The shop mentioned above on Jian she lu at the bus stop is actually at that street where it is still called Dongfengxilu. It mainly has Chinese painting supplies so you have to be around the corner at 121 street.

Between Dali and the TLG or Lijiang you pass the water divide between the rivers going south and the Jinsha (Upper Jangtze). It is thus a long way up and then a long way down and this over a dusty road with lots of trucks. To the TLG you simply follow the river valley so without too much of a climb. To Lijiang you will have to climb up to the Lijiang plateau again but that road has less traffic nowadays since the motorway opened.

Frankly knowing this area pretty well it would not be my favourite route to cycle and I am pretty sure it will not be a nice cycling experience.

Cycling to Shaxi is over roads much more suited for cycling then the routes to TLG and Lijiang.

Shaxi is a mountain range west of Dali and there are four possible routes:
1. Around via Xiaguan and Jangbi and then north.
2. Via Eryuan and then west over the mountain. (Steep and at high altitude thus can be cold and windy, so windy that they placed windmills there)
3. Via Niujie and west over the mountains. (Steep and at high altitude. Gravel road which is under reconstruction. Not recommended unless very fit and experienced mountain biker)
4. Around via Diannanzhen just south of Jianchuan. (This crosses the water divide twice)

I would recommend you go to Shaxi only. Go via the south (Xiaguan, Yangbi) and return via the north via Diannanzhen or take the same way back.

When you rent a bike in Dali make sure it has good brakes. The bikes are normally rented out to people cycling around the lake which is all flat so bad brakes will do but the road out of Xiaguan drops very steep and you really need good brakes there.

Note that there are two shops near the crossing of 121 road and Dongfengxi Road. The first is a shop specialising in Chinese painting stuff. The shop with oil paint etc is a bit further.