NOTE: These numbers may not be completely accurate, but they do reflect my current knowledge about how spinners work.

X axis: spinner's direction when you started moving
Y axis: number of frames since spinner last moved
Value:  probability of spinner facing down after 8 frames (1 bike step)

Only even frame counts are given because spinners update every 2 frames.

EDIT: It seems that the tick difference is actually 5, and not 4 = 8 / 2. Maybe has something to do with stopping and starting movement?

	| down	| up	| left	| right
------------------------------------------
0	| 0.847	| 0.039	| 0.039	| 0.075
2	| 0.842	| 0.040	| 0.040	| 0.077
4	| 0.837	| 0.042	| 0.042	| 0.079
6	| 0.832	| 0.043	| 0.043	| 0.082
8	| 0.826	| 0.045	| 0.045	| 0.085
10	| 0.819	| 0.046	| 0.046	| 0.088
12	| 0.812	| 0.048	| 0.048	| 0.092
14	| 0.805	| 0.050	| 0.050	| 0.095
16	| 0.796	| 0.052	| 0.052	| 0.099
18	| 0.788	| 0.054	| 0.054	| 0.104
20	| 0.778	| 0.057	| 0.057	| 0.108
22	| 0.767	| 0.060	| 0.060	| 0.114
24	| 0.756	| 0.062	| 0.062	| 0.119
26	| 0.743	| 0.066	| 0.066	| 0.126
28	| 0.729	| 0.069	| 0.069	| 0.132
30	| 0.713	| 0.074	| 0.074	| 0.140
32	| 0.695	| 0.078	| 0.078	| 0.149
34	| 0.674	| 0.083	| 0.083	| 0.159
36	| 0.651	| 0.089	| 0.089	| 0.170
38	| 0.624	| 0.096	| 0.096	| 0.183
40	| 0.593	| 0.104	| 0.104	| 0.199
42	| 0.556	| 0.114	| 0.114	| 0.217
44	| 0.512	| 0.125	| 0.125	| 0.238
46	| 0.457	| 0.139	| 0.139	| 0.265
48	| 0.389	| 0.156	| 0.156	| 0.298
50	| 0.302	| 0.179	| 0.179	| 0.341
52	| 0.186	| 0.208	| 0.208	| 0.397
54	| 0.223	| 0.200	| 0.200	| 0.377
56	| 0.276	| 0.188	| 0.188	| 0.349
58	| 0.360	| 0.167	| 0.167	| 0.307
60	| 0.523	| 0.125	| 0.125	| 0.227
62	| 1.000	| 0.000	| 0.000	| 0.000