For example, these Kenda tires are 5-6 years old at this point. They've seen moderate use in generally good riding conditions. These sidewall cracks are normal for tires like this and are not very deep at this point. They are cosmetic, but it's worth looking over your tires once per riding season to see what you have going.
On to the Bottom Bracket
I re-built this 1947 Schwinn New World over the course of winter 2012-13. In fact, I talked about cleaning and re-greasing the bottom bracket on this particular bike in December 2012 (more here).
How often should you re-grease?
It depends on what you're re-greasing (bottom brackets see a lot of RPMs); how much you ride the bike; and the sorts of conditions where you're riding. A commuter bike that sees a lot of miles in bad weather may need a complete tear down and re-grease one or even twice per year. A vintage bike that sees only parade use might need it every few years, just to keep the grease fresh.
This particular bike is in between - it's a vintage bike ridden in only decent conditions, though it sees more use than a parade bike does. I rotate this bike alongside other vintage bikes, but it does see a fair bit of mileage for an old bike.
So I took apart the bottom bracket to do a re-grease. The first sign is good - the old grease is still there in quantity and is not dried out or contaminated. This comes from riding the bike in only dry, decent weather. This particular grease is a plain, hardware store brown lithium grease.
A closer look reveals the bearing tracks have a little wear on them, but nothing much more than when I last re-built the bottom bracket in 2012-13. The wear tracks are shiny but not pitted or very deep. These cups run smoothly and are original to the bike. Schwinn made these right.
What Grease Am I Using These Days?
This time, I'm using a green synthetic grease formulated for high-speed bearings on farm equipment and trucks. If that sounds like overkill - it is. The thing is that I like the viscosity and workability of this grease, particularly through a small nozzle grease gun. I've had a lot of luck getting this grease into small spaces - more than I had with the brown lithium. Either grease is fine for bicycle purposes.I switched to this green grease a couple of years ago, and really like how it works in bicycle bearings.
Some people like red Phil Wood grease, others use the hardware store lithium grease, and some even use the white lithium grease from a tube. They all work fine for vintage bike purposes where it's just a nice, old bike we're riding for fun. If you're commuting in bad weather on your bike, you may want something like Phil Wood or or this green grease made for bearings working in adverse conditions rather than a lower-cost hardware store grease.
The only grease I do suggest avoiding is the really old-style, sticky brown "axle" grease - the heavy stuff that often came in the big, metal grease guns and was used on cars. I tried using this stuff years ago, and it's not as good an option.
There is no magic to "bike grease" on a bike of this sort - we're not commuting or racing here. The most important thing is not actually the grease itself, but that you bother to do the maintenance.
Anyway, I then cleaned and re-greased with green grease. Again - no undue wear or damage, and the old grease showed nothing wrong. After doing these jobs, I trued the wheels a bit, adjusted the bearings a little, and went for a ride.
The bottom bracket runs as slick as ever with the green grease and adjustment I did. One-piece cranks tend to be a little heavier than three-piece cottered cranks, but they can run smoothly. They're not unduly difficult to re-build either.
