Chuck's Tech Opinion: Shimano Uniglide cassettes, replacing cogs/sprockets

Just before Shimano came up with the Hyperglide (HG) cassette system that we know and love today, it introduced the Uniglide (UG) arrangement. It was an 1980s effort to provide not only a cassette system, but also teeth features to improve shifting (especially for the indexing 'click' that is pretty much standard now). I happen to have such a cassette in 6 speed - they were produced in 5, 6, 7 and 8 speed. Generally, UG cassettes are rare these days, while screw-on freewheel types remain relatively abundant. This post is about cleaning and re-jigging my Uniglide cassette, currently 13-14-15-17-19-21T, and my thoughts about it. I want to dismantle, clean and swap out one of the cogs to allow me to put in a bigger 24T. Photo before I started work:

Yes, it's dirty, and the grime is stuck hard! If you've never seen a Uniglide cassette before, then it could be confusing. It has neither Hyperglide's splined lockring nor the spline socket that screw-on freewheel types have. It does have a freehub body, much like the modern Hyperglide, but all the splines are the same width. Instead of the HG lockring, the topmost cog is screwed down on to the upper part of the freehub body, which is partially threaded, to hold everything together. The 24T cog that I want to add is the black one in the photo. To dismantle, you use 2 chain whips to hold the wider cog, while unscrewing the topmost cog (13T):

Thankfully it unscrewed fairly easily. Turned over, you can see the cutouts for weight reduction and the three small bolts that hold the unit together. The top locking cog (13T) has an inbuilt spacer and is threaded on its inside. 

View from the other side, there is a thin washer under the top locking cog (13T), and you can see the bolts engaged in the three small threaded holes in cog 14T:

The bolts need to come out. The bolts have a smooth shaft and are threaded at their tip. They screw only into the matching threaded holes in the 14T cog: 

Taking off the 14T cog, there are identical plastic spacers between the remaining cogs:

I cleaned up the parts and started to refit. In this photo you can see the threading on the upper part of the freehub body. Apparently, it's possible to change that body for a HG one, but why bother when this seems little worn and is functioning beautifully. Also, I think the threading on Dura Ace is different - presumably an attempt to keep it "exclusive" and apart from the mass market! I've placed the new 24T on first, then a plastic spacer:

Looking at the splines on 19T, note the absence of the wider notch and narrower notch. Also note the three holes for the bolts - these are present in everything, spacers, washer and cogs. I'm not going to use the bolts as their main purpose is to hold the cassette together for easy fitting. 

In the photo above, you can see two teeth features designed to improve shifting. Firstly, two opposing teeth on the 17T cog are shorter. These provide avenues for the chain to dismount as you shift. Secondly, you can just see the twist of all teeth. These features are the precursor of Hyperglide teeth shaping. Place cog, spacer, cog spacer, etc... until you reach the penultimate one, then the thin washer goes on:

Now you can clearly see the threading on the freehub body to take the last locking cog 13T. Put that last one on carefully by hand, to ensure threads are not crossed! Then tighten it with a chain whip, but it's not really necessary to strain yourself doing that, because the process of pedalling will tighten it. In fact, when I put it into top gear while riding, I felt the slight slip as it tightened into position. Here's a pic of the removed bolts and 14T cog, which I'll be putting away carefully in my bits box. Only some cogs had the shorter opposing teeth pairs:

The finished cassette. Not so dirty now! Can you spot the shorter teeth in the picture below? Hint: there are none in the top locking cog (13T). Notice that the 24T cog has them, which means it's not really intended to be a last cog - contrast with 21T (see photo above) which is stamped 'Low' and doesn't have the shorter teeth. I don't think it really matters, and presumably, having the shorter teeth on the biggest cog will help switching from 24T to 21T.  

Now a photo of the bike in which this wheel goes, my Dawes Impulse (see previous posts): 

And a closeup of the cleaned cassette newly configured to: 13-15-17-19-21-24T, with the vintage super-cool Shimano 105 mech:

One thing you need to check for is that the chain is long enough to handle cross-chained big-big. Even if you're not supposed to use that gear, it is wise to ensure that the chain is long enough for it to be engaged otherwise you can break things. To my relief, it was long enough.  

CHUCK'S TECH OPINION ON UNIGLIDE

I thoroughly enjoyed working on my Uniglide cassette, because the quality of manufacture is superb, and everything disassembles and fits well. It was easy to remove the bolts (using quality pliers). This is better than those annoying rivets in modern cassettes, but I can understand that rivets would be much cheaper than those three bolts when it comes to mass production. 

Test riding was magic! It shifted positively, flawlessly, and the indexing was spot on. Definitely the crispest shifting bike with down tube levers that I've ever owned and I'm comparing here to both screw-on freewheels and even more modern 9 speed Hyperglide hubs. (Perhaps that's because the tolerances, both cog-spacing and lever-indexing, for 6 speed are more forgiving compared to the narrower 9 speed?). 

Another great advantage is that the uniform spline widths allow you to invert each cog. Useful to maximise working life, as worn cogs may be simply turned around. While I like this and it resonates with today's re-use, up-cycle culture, it is not the ideal situation for the capitalist mass-producer who wants sales (think Apple iPhones and OS upgrades that render one's device slow). I think that is part of the reason why we have modern riveted cassettes and non-reversible cogs today.  Also, I suspect that with different width spacers, you may use the same freehub body to build up a 5, 7 or 8 speed cassette, but I haven't tried it and would have to research the standards for that (i.e. spacer widths, cog thicknesses and overall hub body height).  

In its time in the 1980s, Uniglide was top-end and a step-forward in smoothness of shifting and ease of indexation. I can appreciate why. Uniglide hubs are ultra-rare nowadays, so the information in this post is really for bike nuts, the sake of history, or those who accidentally come across one. Feel lucky if you do though because from what I've seen, a new old stock Uniglide cassette can sell for £60-£100!

Raleigh Twenty: To powder coat or not?

When I got this bike, it was dirty and grimy looking. My first thought was to strip the paint and get it powder coated. However, after working on it for a while, I realised that the parts with the worst paintwork (chips and rust) were the mudguards (fenders) and the chain guard. These have been removed and sent off to my local powder coaters for prepping and application of a contrasting colour. In the meantime, I washed the frame, applied T Cut to the paintwork, and have been working on polishing up and servicing the components (see last few blog posts on the chainset, bottom bracket and wheels). Today, for the first time, I whacked a bit of regular car polish on the underside of the frame and hey presto:

Not bad for paint that is 33y old, I think you'd agree! It vindicates my decision to not strip this frame. 

Now I'm keen to polish the rest of it, but there's a lot to do before that, such as removing rust from the brake calipers and levers, figuring out what I want for pedals and hand grips. In the photo, you can just see the 1970's cream plastic hand grip. Compared to modern bar grips, these are ugly, uncomfortable and undersized!  

Raleigh Twenty: Front hub service, removing rust chrome wheels

The 46T 165mm crankset off the BSA 20 is utilitarian, but good looking, after the rust is removed and the chrome polished. I especially like the little "Nottingham Knight" stampings. Virtually unworn teeth:

OK, it's cottered, but I'll make sure to assemble it with anti-seize. I tried removing some rust with Aluminium foil and water, and while it works, it can cause scratches, probably because solid particles can get dragged about under the metal foil. I prefer using 0000 wire wool with WD40. That removes rust quickly and minimises scratching. Here are some before and after shots:

And another one:

In this one, the bottom part of the front hub has been cleaned, but not yet the top part. You can see the yucky grease solidified into varnish. Easily cleaned with WD40 and a small piece of green plastic scourer. This is probably the first time the hub has been opened since 1978! 

Note also the 3 cross spoke pattern, but interestingly, the crossing spoke goes over the first, second AND third spokes, not under the third, as is often the case on larger wheels with 3 cross lacing. And here's the other side, all clean, ready for balls (10 BB each side of 3/16"):

Like the chainset, there's a lot of character in these late 70s Raleigh Sturmey Archer front hubs. They are actually very well thought out in my opinion, as I'll describe further below. 

Here are the parts. Note that both cones have a small flange turned on them, but only one cone, the moveable one, has flats to make it a nut. That's because it is used to adjust bearing play - while the hub is on the bike! The other cone on the axle is intended to stay fixed - there's a stop on the axle to prevent it passing further along the thread. Note that neither cones have locking nuts (90mm across the outsides of the cones). 

You have to hand spring the front fork slightly opening the front dropouts a tad to let the flanges of each cone fit in. I measured my forks at 87mm across the insides, so that's a decent 3mm spring. Once in though, the hub will stay put, held by the cones, even before you put the nuts and washers on the outside of the forks. So, the clever bit is that you can adjust bearing play by sliding a cone spanner inside the fork on to the flats of the cone nut, and turning slightly. Once set, tighten the outside washers and axle nuts, and that holds it all down. Quite neat and clever and they run pretty smoothly (even this one despite the wear groove in the cone). Just remember to put the fixed cone on the right (drive side) of the bike, because on the other side, there will be a natural tendency for the bearing to tighten, which can be harmful to it. As an experiment, assemble and hold the axle ends in your hands, give the wheel a spin and fiddle about - it's easy to see the natural tendency of the bearing to tighten up when the fixed cone is on the left, and the natural tendency to loosen with the fixed cone on the right. But don't worry, they won't loosen in use, because the external nuts lock everything in position. 

For the inner tube side surface of the rims, I simply spray a bit of WD40, brass wire brush and then a quick going over with a slightly coarser steel wool. Wipe it off with a small cotton bath towel, and hey presto, clean insides ready for rim tape. For the Sturmey Archer AW I merely oiled it using a cheap plastic pipette and 1:3 mix of car transmission fluid to 5W engine oil. The pipette allows a small measure to be squirted easily into the oil port. That three speed tickety tick! As they say, AW stands for Always Works...

So here they are, shiny chrome wheels, and hubs, bling bling! After a bit more tightening and truing, I'll dress them in new white-wall shoes. 

Raleigh Twenty Steerer Restrictions and Bottom Bracket

There are two mechanical restrictions on the steerer assembly of the Raleigh Twenty, here, a BSA 20. 

VERTICAL RESTRICTION

As promised in an earlier post, here's a photo underneath the steerer, looking between the front forks: 

You can see the wire wrapped around the main brake bolt. The wire also attaches to the stem:

The wire could be copper or some kind of bronze. Here's a close up of wire twisted up around a pin in the stem:

The wire's function is to prevent the stem from being completely pulled out of the steerer tube. At the top of the first photo at the start of this blog post, you can see the bent plate chromed bracket on the brake bolt, sitting snug against the front of the forks. 

ROTATIONAL RESTRICTION

Here is another view of that bracket, this time from above:

If you don't know what the bracket's for, then you may think it to be some kind of "English decorative curio", or a basket attachment! But I hope this picture helps you to understand the function of the odd shaped bracket. As the handlebars are turned, the bracket "folded hands" hits the metal welded C shape plate behind the head tube. So, the steerer stop bracket and that welded C shape plate on the back of the headtube together provide a mechanical restriction to the range of movement of the forks. 

I believe that both of these steerer restrictions were intended as safety features, but I'm not certain of that.

CRANK REMOVAL & BOTTOM BRACKET SERVICE

I also took off the cranks for servicing the bottom bracket. The non-drive side cotter pin came off easily. But the drive side one was stuck like a pig. Removing a seized cotter pin has got to be my most unfavourite bike mechanic job! I had to drill it out, and it was a real struggle. Here is the first pilot hole: 

You've got to use something as cutting fluid (I used 3in1 oil). I then followed up with wider diameter drills and finally after much hammer dynamics, got the *#*£$@! out (one day later!). 

And I finish with some photos of the BB shell, axle and cups, apart and reassembled. The axle is 14.2cm long, and measures about 6cm between cones. There are 11 balls of 1/4" on each side. It's clear that this bike was not much used, which makes it a great candidate for a clean up and service. Restoration using as many of the original parts as possible.

I think the drive side cup is welded in - in any case, I didn't bother trying to remove it. Now I just need to find some new cotter pins, which as far as I can tell are 3/8" in diameter. Whether or not it's considered right, I WILL use some copper anti-seize when I fit them. 

Servicing a Raleigh Twenty 20 Headset: Nylon Bushing, Crazy Design?!

The headset arrangement on a Raleigh 20 is a little bonkers in my view. The bottom part is a conventional ball bearing race, and really quite good. The top half is the bottom half's Frankenstein brother. In this sequence of photos I'll show you details, as I open up this BSA 20 for inspection, cleaning and lubrication. (For replacing the top part, see this previous post). Here's the front view:

Now remember that the stem has restricted vertical movement in the steerer, because of a wire loop tie inside at its foot. I don't have a photo of that here, but when I get the wheels and mudguard off next, I'll try to take some pictures. For now, note that the stem can be lifted up a little, but cannot be taken out. Below is a pic of the top part of the headset. From the top: stem, top lock nut, light bracket, second lock nut (hidden by the light bracket), stem-steerer clamp, and a metal top cap:

So, straight away you can see that the clamp squashes between the lock nuts above it and the head tube bearing below it. This is a less than ideal situation for good bearing preload. Let's open up from the top:

With the nut off and light bracket lifted, you can see the second lock nut properly. Unscrew that second lock nut and raise the parts: 

I've taken off the clamp lever in the photo above. Note that the bolt has a square flange and can be removed to allow the clamp to lift up easily over the threads. You can see the metal top cap has indentations on its lid. That's what I mean by not ideal for bearing preload - the clamp interferes with the even downward force of the lock nuts. And beneath, you can see the top edge of the infamous nylon bushing. How does the clamp join the stem to the steerer tube I hear you ask? Well, because of this cut out

You can see how the clamp edges push on the sides of the T shaped cut to press the steerer on to the stem tube. Obviously, the designer was trying to deal with how to raise and lower a stem without having to deal with expander bolts as in a regular quill stem. It just about works, but I would not describe it as an elegant solution! This time, I was not replacing the top bearing, merely inspecting, cleaning and lubricating. I used a drop of thick gearbox oil around the inside of the nylon bushing to help the steerer tube rotate inside it. Don't put too much in there, because you need the stem to clamp to the steerer and excess lube might mess that up.

Finally, I serviced the bottom race, which is fiddly without taking the stem out, but can be done. Just make sure you have a sheet on the floor to catch any loose ball bearings when you first lift it up. When I did that, the ball race was dry, with a bit of hard stuck grime on the race that needed to be removed. Below, is a photo of the bottom bearing opened up, the 25 balls of 5/32" removed, cleaned, greased up ready for the shiny balls to be placed on the lubed cup. 

The bottom cup is pretty chunky as you can see, and merely sits on the fork crown. In this example it was not a tight friction fit, as compared to a regular crown race on a typical fork. 

In a previous post (search on Raleigh Twenty Project) I showed some pictures of the headset replacement that I did on a blue Triumph Trafficmaster 20.  Although I kept good photos of the nylon bushing and bottom race, I didn't make a thorough a photo record of how I fitted the 1" threadless top bearing. So when I do the next one, I'll take more photos of how to get rid of that nylon bushing and replace it with proper bearings.

This time, though, I was only inspecting, cleaning and lubing. It was enough to improve the steering of this particular "shopper bike". While it's better than before, I know it can be improved a lot more, but that would require this stem to be untied from its base, chucking the clamp, fitting a new quill stem, which probably means new handlebars, etc. By the way, another approach is to completely replace the forks and headset (the head tube diameter is relatively conventional traditional size). 

However, my plan for this bike is not really modernisation, but rather rejuvenation with judicious restoration. Which is what working on this cycle and riding it gives me a bit of!