A 'tempo synced' LFO, that is, an LFO locked in time with the tempo of the song is one way of keeping wobbles in time. Automating changes to the sync time will give you perfectly synced wobbles that change speed according to which sync time is selected. As pointed out above, they tend to be fractions of 4 for music writen with a 4/4 time signature. (1/4, 1/8, 1/16, 1/32 etc).
Tempo synced LFOs work best on synths where the sound source remains identical over time. This is not true of samplers.
If you are using a sample of a bass then be aware that for every octave you go down it will double in length. For every octave you go up, it will be half its previous length. This is true with real instruments such as the guitar, piano and flute. On a guitar, if you half the length of a string it plays an octave higher.
This is relevant since your sample may have some kind of natural wobble in it. Changing the pitch of the sample will also change the length of any wobble already present in the sample. Samplers with time stretching features can help avoid this.
I'd recommend sticking to a synth with decent LFO options that also allow you to automate the synced LFO speed in the synths sequencer lane. Pay me £50 and I'll do it for you!
