It is possible to ride up the two biggest hills overlooking Lanzhou. With the help of a city map, these rides should be quite easy to plan. On a clear day, the views are spectacular.
Jiŭzhōu Tái (九州台)
This is easily the highest mountain on the north side of the city. Look out for the TV/mobile masts on the summit.
There are both on-road and off-road routes up to the top. It's probably easier to describe the on-road routes. When you are close to the summit, look out for the off-road descent (which ends in Anning District).
Cross the Yellow River at the Qīlĭhé Dàqiáo (七里河大桥) into Ānníng Qū (安宁区). Head north for around 200m, and turn right at the fork. Ride east for about 1km until you reach the Forestry Commission building. Jiuzhou Tai is signposted here. Halfway up the mountain, there is a junction. Go straight on for the summit (the ride gets tough from this point - unrelenting winding steepness for 3-4km), or turn right (east) for a pleasant hillside ride to the White Pagoda (白塔山公园, báităshān gōngyuán, north of Zhōngshān Qiáo (中山桥). Likewise, you can start from the White Pagoda (take the road about 100m east of the park entrance, on the north bank of the river), and do this route in reverse.
Here is a view of Jiŭzhōu Tái from the top of Lánshān
Chinese name: 兰山森林公园 (Lánshān Sēnlín Gōngyuán)
Location: On the south side of the city, directly over the train station
Cost: 6 RMB park entrance at the top
This takes about an hour, on good roads. The route actually begins quite a way west of the hilltop. 500m south of Xīguān Shízì (西关什字), where Zhōngshān Lù (中山路) meets Báiyín Lù (白银路), there is a road that crosses the railway tracks, and then starts to climb. Look out for the signpost. It would be useful to have a map with you, but basically head upwards and eastwards. Locals will point the way. Once you're higher up (having passed through a couple of small hillside residential areas, the route becomes obvious. Near the summit, the road forks, giving you a choice of continuing on the north side or south side of the mountain. The route is marked on this map.
There is great exploring to be had in the surrounding hills, especially in the hills north of Anning District. There are some very technical single-tracks, but also some dirt roads for vehicle access to the villages. The best thing is to just get a map, and get out there.
There is access into the hills from the following places:
Péilí Guăngchăng (培黎广场)
East side of the Political and Law University (Zhèngfă Xuéyuàn, 政法学院)
Back gate of the Jiāotōng Dàxué (交通大学)
Here is one route we used to do. Rather than describe in detail, have a look on Google Earth, which has a pretty clear view of the whole route. It is all wide-track, with various single-tracks leading off that you could explore along the way.
1) Ride north from the back gate of Zhèngfă Xuéyuàn:
36° 6'7.72"N 103°43'46.61"E
2) Arrive in small village (apologies, lost the name):
36° 8'3.89"N 103°44'48.87"E
3) Ride back out of the village south, to Péilí Guăngchăng:
36° 5'58.59"N 103°44'39.44"E
Here is a Google Earth image of this ride:
If you want better local knowledge, or riding partners, go to the Bolun bike shop, and ask for Ma Jun (tel: 09318820021, 13919882268, no English). To get to his shop, go south from Xīkŏu (西口, the west entrance of the Square), along Jīnchāng Nánlù (金昌南路) on the west side of the road. Cross over Gānnán Lù (甘南路), and the shop is about 100m further along.
On the way, you'll pass a Giant shop on the east side of Jinchang Nanlu (before the Gannan Lu crossing). There is also another well-stocked bike shop, a few minutes walk to the south of Bolun, also on the east side of the road.