Originally Posted by
Road Fan
Several things could be going on, not all of them in the trainer. If your hub bearings are getting hot due to pressure or perhaps are adjusted too tight, I could see increased resistance when you are pushing harder (pressure in the bearing systems of your bike) or dirt in the bearings causing similar resistance to rolling.
So If you have the mechanical chops to tear down your fluid trainer, I think you have the chops to give your bike an overhaul, clean, regrease, renew bearings as may be necessary, and readjust the bearings so as not to have excessive bearing pressure. I tend not to use preload in my bearings, I would suggest giving that a try. But you still should not have any play in the bearings.
It's still of value to finish overhauling your trainer, but don't neglect renewing the hub, BB and perhaps freehub bearings.
The theory here is, with all known good main bearings, there should be zero change in rolling resistance with pressure, speed, heat buildup, or running time. But I could imagine standard BBs causing such trouble if they are not up to snuff such as dirty, grease not fresh, worn, or too tight.
The rear bearings felt beautiful when I checked them but since I was in the process of going through the bike, I did clean & lube everything. I like to set my bearings so there's no play and there's no sensation that the bearings are being pressed into the race by the cone- just smooth rotation. The bearings had almost no lube, but the wheel turned beautifully.
The trainer isn't clamped so hard on the skewer than it could cause a problem and the hub isn't cranked into the tire too hard.
The OEM Suntour crankset has worn rings but that's not where the pulsation comes from- the OEM bottom bracket has sealed bearings and they're in good condition, but I did change the crankset and BB because of the wear. The chain is good, clean and lubed- I tore the freehub apart to clean & lube it- like the wheel bearings- little lube, no play, no preload before clean & lube.
I talked with my friend who gave the trainer to me but I forgot to ask if he did anything to it (like change the oil). Since the oil isn't used for lubrication, I think I'll empty the reservoir and reassemble it, so I can compare. The bearings are sealed and separate from the impeller housing, so this shouldn't cause any problems for them. If it eliminates the pulsation and added resistance, I'll see if I can find something else to fill it with.