Biking To-Do List: November 2020

First, yes, I still owe you all 2 posts on the theory and practice of half-step gearing, which is slow going at the moment, but I'm working on it. 

Second, I decided to repack an old set of Shimano Ultegra 6700 carbon pedals and was shocked to find there is no main bearing, and the "needle bearing" isn't a needle bearing at all, it's a home-brew dual ball bearing where the cups are ground into the ends of a ~ 12mm steel barrel, and those balls are teeny tiny, like something out of a Swiss watch. We're talking flat-sided toothpicks for handling all 36 of these 3/32 little devils. The PD-R8000 is made exactly the same way.

Third, I'm still trying to figure out a way to salvage my old bike's headset by using a thicker grease meant to resist being hammered out of the contact area (pound-out). Turns out there's a grease sold by AmsOil made specifically for this purpose used in heavy duty off-road earth-moving equipment - Synthetic Polymeric Off-Road Grease, NLGI #2

Think articulated joint in the center of a bucket loader rolling over rough ground with a bucket load of ore and a huge weight stack at the extreme other end of the machine. (these guys couldn't get laid in a mattress factory, but watch the video anyway) You'd want the thicker NLGI #2 grease for headsets retrofitted with sealed bearings with much smaller engagement areas than the original press-in ball bearing cups.

This, and repacking my Ultegra pedals led me to a lengthy investigation of grease, and especially, compatibility of greases with different bases (they're not), because I bought some of Park Tool's PPL-1 Polylube poly-urea grease, and I wanted to be sure it would play nice with other (primarily lithium-based) greases. Park Tool says it does. My research says NO. 

BTW, the base isn't the lubricating agent. The base is the stuff that gels and suspends an oil, and slowly weeps the oil onto a bearing over time, but it's NOT the primary lubricant (some additives like moly or graphite provide lubrication as well). That is to say, the base is what makes something a grease instead of an oil. There's a fairly wide window of bearing speeds and loads where grease works, and bicycle bearings are way, way inside that window. Easy-peasy. 

10% ball bearing failure @ 45,000hrs

By way of contrast, high speeds, high loads, and high heat make active lubrication under pressure with oil absolutely necessary for ICE engine main "bearings", which aren't bearings at all, but bushings with oil galleys cut into them, while hypoid gears' very high pressure loads in manual transmissions require very thick oil that can stand up to molecular shearing, but no active, pressurized lubrication system is needed there.

At any rate, I leaned a ton of interesting and important information about grease, when it's used, and how to select it. There's a really brilliant blog post in this if I'm up to the challenge. I do want to assure you all though that I'm very happy with all the RX-es I've made on this blog, and in particular, I still think for ball bearings running at the speeds (50-250 rpms) and pressure loads of bicycle hubs, BBs, headsets (my special need notwithstanding) and pedals, pure Teflon grease directly on the balls, cups & cones, and Teflon fortified grease to displace dust, water, etc in the rest of the grease cavity, makes the best possible lubrication. 

 If this changes I'll shout it from the rooftops, but I don't see that happening for decades. FinishLine makes both the pure Teflon grease and the Teflon fortified grease. I bought some Krytox GPL 205 10yrs ago and paid $65, but it's gotten cheaper. I still have about 1/4 left, so yes, I use it sparingly, but it will never leave you metal to metal and is chemically inert, so it won't react to metal, plastic, paint, etc. If you're riding disk brakes and the hub is soaking up a lot of heat, PTFE grease is about as good as it gets.

With COVID-19 running rampant everywhere again, as predicted, please do take care to stay safe at all times - 90% of the time will get you killed with this remorseless executioner.

Ultegra 6700 Hub: Near Death Experience

Last fall my back wheel, the expensive, custom built one, developed an annoying creak. It's an Open Pro Mavic Rim attached to an Ultegra 6700 rear hub via 14/15 butted DT spokes on the drive side, and 14/17 super-butted spokes on the NDS.

After spending hours trying to relieve the spokes, and generally driving myself nuts trying to remedy the creak, I gave up and put my nearly identical spare on, and have ridden that the last 8 months. A couple of months ago though, I realized it was time to get ready to replace my "winter" wheel with my summer wheel, and decided to repack the bearings on both in the process of swapping them out.

Parts replaced were 5,6,8,9, and 10,11,12,13. Photos are of #10's cup surface. BTW, part #11 has an allen wrench internal engagement area for removal.

I was shocked to find both cups and cones on the drive side pitted and spalled on my spare wheel, (purchased from PBS at a huge discount). I realized that since it was my spare, and having few miles on it, I had NOT repacked it in 2 years, as it still had factory grease in it. This was either an appalling factory lubrication failure, and/or, a serious QA problem for Shimano. I really have no idea where the blame lies, but you will note there is micro-pitting and a bit of rust all over the cups.

Pitting and spalling of an Ultegra 6700 rear hub

It's important to understand that normally for loose ball bearings, a pitted cup has no remedy,and the hub is ruined - garbage to be hurled into the trash can in disgust. For Shimano hubs (and many others), there is one exception though, and that's the drive-side cup in back, as the cup is actually part of the free-hub body, and is NOT pressed into the hub as all the other cups are, both with front and rear hubs. (the other side of the cup is a cone for the internal free-hub bearing - pretty clever)

 I took the good free-hub body of my creaky, custom wheel, the axle with 2 good cones, and was able to put together one good wheel by cannibalizing two bad ones. There's definite advantages in having two identical, or in my case, nearly identical wheels (the PBS wheel uses 14/15 double butted Wheelsmith spokes on both sides). Since rear wheels are much more likely to break than front ones, having two identical rear wheels is much more important. Think about relative tire wear in the front and back, and double or triple that.

I ordered a new free-hub body from Amazon, and a new cone from Performance Bike Shop, who happen to remember they're a LBS, and should provide this service. They did so after a complete failure the first time (they lost all record and recollection of the order, until I jogged their memory, and then they just shrugged), 6 weeks of waiting, and then a week waiting for the re-order. When I went to pick the drive-side cone up, they informed me they couldn't sell just one - in clear contradiction to the two cones, each with their own part number, plastic bag, and price. I HATE being lied to!!!

$20, plus tax for the two cones, and $45 for the free-hub body. I'd RX getting the 2 cones along with the axle in a rebuild kit for $30 - a better deal IMHO. $65 is a lot of money to put into rebuilding a hub that didn't cost much more than that when I bought it, but the alternative was to toss the entire wheel. Nasty thing, having a nice wheel wrapped around a bad hub. In fairness to PBS, the 2nd mechanic I dealt with was very professional.

I'll see you on the dark side of the moon. Very hard to photograph. These are the best of 100+ attempts.

 When the parts came I mounted them on the custom wheel, resigned to having an expensive creaky wheel for all my trouble, but still a spare. I'm not sure if it was the new free-hub, the RnR process, the new cones, new balls, or Teflon grease, but the creak is GONE!

I now have 2 good wheels, assuming I don't find anymore nasty surprises when I repack my winter wheel, and I have replaced the stock bearings, which have G20 balls, with G10 balls I bought in bulk from Amazon.com. Btw, balls are rated according to their tolerances, so the smaller the number, the tighter the tolerances, and therefore, the better the balls. G10 is as good as steel bearings get. You can get G5 ceramic balls, and that is an advantage in having loose ball hubs. Generally though, my enthusiasm for loose balls has dissipated significantly. ;)

This looks like a spectacular grease failure. I think this was factory grease. I packed the new bearing with pure Teflon grease spread on the cups and cones, and then packed full with Finish Line grease with "some" Teflon in it. I assumed since it contained Teflon, it would be compatible with pure Teflon grease. It's usually a bad idea to mix greases.

 

 

This brings me to an important point. If you have cartridge/sealed bearings, (a misnomer, as all bearings have seals) you don't have to worry about the cups getting pitted or spalled. You replace the cups, cones, balls, and seals whenever you replace the cartridge bearing. The downside is, you're paying a lot of extra money for parts that aren't usually needed, so for any given price point, you get better quality bearings in a loose ball hub, AND, you can get them. Chris King, for example uses his own in-house mfg-ed sealed bearings - which he doesn't sell to the public.

Close to what I've been using, which I purchased at $120 an oz from an aerospace contractor, so it's MIL-Spec. This should work just as well for 1/6th the cost. Spread in zig-zag pattern across the ball path on the cups and cones before packing with the grease below to hold the balls in place while placing them in the cup. The very best grease for preventing spalling is 100% Teflon grease. Hard to find.

Good, basic bearing grease for bikes. Basically, I use it as a filler to displace water and dirt, and let the pure Teflon do the work of keeping the bearings rolling.

There's nothing very hard about replacing or repacking ball bearings, nor free-hub bodies. It pays to swap your wheels out at least once a year, and at least repack them. The G10 balls are going for a dime a piece at Amazon. There are 18 in back and 22 in front. Well worth the trivial expense in my view.

Morningstar Ball Tweezers

Highly recommended is a constant tension ball tweezers. They hold the ball with a constant force, which you relieve when you want to release the ball. This guarantees you don't scratch the ball by squeezing it too hard. It also makes holding the slippery little devils much, much easier, and allows you to press the balls into a cup's grease pack, which will hold the balls in place until you can place the axle and cone to keep them from falling out.

This one has a brass ball holder, which makes scratching a ball impossible. These are tools mechanics treasure. A source of bragging rights for those who know how easily balls can get scratched. When working with bearings, every attempt should be made to maintain a surgically clean environment. A human hair mixed in the grease, speck of dirt, metal fleck, or bit of rubber seal will degrade and/or ruin a bearing. It is absolutely essential that your tools, hands, rags, and general work area be absolutely CLEAN!

I am happy to report that the creak is gone, so almost worth the $65 bucks. Now I can focus on building up a new speed wheel in back, based on my old Alex wheel hub, DT Swiss bladed spokes, and a DT Swiss R585 30mm deep rim. With 24 spokes, and the 30mm profile, it should be slippery, and since the Alex hub is pretty light, a reasonable weight as well.

Techie Tuesday: Drivetrain Maintenance

After a rather nasty mis-shift, I've been trying to work a gremlin out of my drive train. I started by inspecting the chainrings and cassette gears for broken or bent teeth. I couldn't find any, so next I looked at the derailleurs, shifters and cables. I then inspected the frame route for the front derailleur cable, and found a problem.

Where the front derailleur cable comes through the frame there is a hole. Pretty stupid design, as it should clearly be a mtb style rubber seal, but there it is, and it was filthy and packed with sand, dirt and sticky dried oil and Gatorade.

Here's a nice video showing how to clean that hole and the thru-frame cable guide.



You should also clean the guides for both the front and rear derailleurs that run under the bottom bracket, as being at the bottom of the frame, they get fouled by Gatorade that spills on the frame and runs downhill.

Chain on biggest rings, shifters positioned to relax cables for max slack, makes for easy cleaning of BB cable guides. Note pedal tether to prevent shifting.

This is a big problem area, and monthly cleaning and oiling will make your shifting fingers much happier. A toothbrush is a great tool for cleaning the BB routes, as is a good terrycloth hand towel on the tip of a straight-bladed screwdriver.

Wednesday: MIA

I went for a nice sunny ride up to Beals on Tuesday, except when I got up on Wednesday and went to RSVP yes for the Beatty Dr climbing practice ride on Thursday, I found out it was already Thursday and I had already missed the ride. What happened to Wednesday?  Can I have it back? It was a nice sunny day, even if the wind was pretty cold, and now it's rain, rain, rain again for 4-5 days.

Not wanting to risk dehydration, I left the windbreaker at home and went with a PI vest and heavy, long-sleeve jersey. I think that would have worked if I'd worn leg warmers, but as it was, though nice and sunny, it was a COLD ride, especially up at Beals where the cold wind coming off the lake cut like a knife.

I have a secret spot at Beals though. Right as you come in, on the left side, over behind the concessions area, there's a spot where the flower bed meets the building, and the afternoon sun beats on the cinder-block wall while the building completely blocks the wind. The roof hangs over the block wall, trapping the sun's warmth, while shielding it from the wind. The flower bed is mulched, which makes a nice insulator for the backside while sitting in it. It's a little slice of heaven on a cold day - as long as the sun is shining.

I broke out a PowerBar, took off my helmet to let the sun hit my black balaclava, pressed my back against the warm cinder-block, and watched a few runners dash into the bathrooms half frozen. I can't think the toilets were very comfortable at those temps either.

After 10 minutes or so, I'd gnawed through half the bar, swallowed some water, and decided to push off and make some heat before the sun got too low. As I clipped in I pointed a half-frozen couple running up to the drinking fountain to my secret spot and saw them break out in smiles as they huddled together and waved me off. I guess the secret is out now!

As it turned out leaving early was a good choice, as I ran over some glass somewhere around Negro Bar, and had to stop at the Aquatic Center to replace my tube. I finished up in 7-8 minutes, with the bike upside-down on a picnic table in the last rays of sunshine.

I was pretty chilled when I got home, and ran the heat at 80 degrees for an hour before I warmed up again. I could tell from the Garmin trace my cold legs weren't making as much power either, but it was still very nice to be out riding on a nice, sunny day.

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Shimano rear hubs are a 2 piece assembly. Note the radial spoking on the non-drive side.

With rain coming down steadily yesterday, I decided to repack my mtb rear hub. I picked up a nice pair of Park Tools 15 & 17 mm cone wrenches from Performance Bike Shop, (who didn't know they had them when I spoke with them on the phone) as my neighbor wasn't home, and I wanted to get the bike out of the dining room.

The drive-side bearing cup is also a bearing cone!

Almost on a fluke I ended up looking at Park Tool's instructional site on repacking hubs, and found a most unexpected procedure - which works great. You mount the wheel OUTSIDE of the rear dropout, using the non-drive-side dropout and quick-release to hold the wheel and compress the axle. If I hadn't experienced it myself I would never believe how much a steel axle compresses! The bearings go from loose to snug (well, perfect by the time you're done) just by closing the QR.

All done, and happy to have it done. After 15 yrs the grease was separating into oil that was gone, and wax that remained, but the hub, cups, cones and seals were in perfect condition. Shimano has great quality,  and excellent seals. The freehub body is a sealed unit, so left that alone. Unlike my Alex hub that came stock on my road bike, the bearing cup is actually part of the freehub body on Shimano. An interesting design. Alex and Bontrager are the same system - probably both made by Alex in Taiwan.

I used FinishLine grease, but when squeezing it out of the tube, oil that had separated was coming out along-side of the rest of the grease. This is not good, especially since I just bought the grease. I finished up with Mobile 1 synthetic grease, which is also tackier, so holds the balls better. FinishLine makes a pure PTFE Teflon grease which I may try, but I will not use this grease again.