SirMike1983 

I've often thought of using a little bit larger cog with my Sports here in Maryland. The local terrain could be best described as "rolling style hills" that you would often find in the Eastern US. There are no "mountains", but just some moderate rolling hills. The local trail (I ride that often as well) is very flat with a slight grade to it (the stock cog does fine here). Has anyone here with experience with that kind of "mundanely hilly" terrain tried a cog change? If so does anyone have a suggested size? I was on the Harris website and saw some nice cogs that really look like the original, just bigger. I don't want a modern looking cog, but a solid metal cog that would appear just like the original, just be bigger for hilly riding. I was looking at the Sheldon Brown piece on the subject and that suggested 20-24 tooth cogs. What about, say, a 22 tooth cog? Would that give me a good hill climber, but still allow me to use 2nd on a flat? Would I still be able to pedal downhill to some effect? On the big hills I coast and brake, so the big downhills are moot. But on small downhill grades I like to pedal a little.

Does anyone recall off hand what a stock cog would be on a '74 Sports? I haven't counted, but I'm sure someone here knows. Anyone have a useful comparison for how that would feel? I'm totally used to the stock 3 Speed set up since I spend a ton of time on that, but perhaps a change is in order now that the local roads I'm on have some rolling terrain. The trail is a blast, but I'm actually starting to enjoy exploring neighborhoods in the area.

Any suggestions?

Sheldon Brown

Most likely 18.

If you switch to a 24, that will knock each gear down exactly one notch: your new 3rd gear will be exactly the same as your present 2nd. New 2nd the same as present 1st. New 1st 75% of old 1st.

24s are kinda scarce at the moment, but 22 is readily available.

Sheldon "Numbas" Brown
https://sheldonbrown.com/gears

SirMike1983 

Hi, thanks for the help there-

Would a 22 (SA? brand) be a direct swap with the rest of my rig stock (chain and chainring)? I'm assuming the '74 Sports stock chain is the usual 1/8 inch size.

nlerner

Mike, the Nexus cogs fit SA hubs, and are $5 plus shipping from Bikeman (for the 22-tooth cog): https://www.bikemannetwork.com/biking/p/FW7022. You'll still use a 1/8" chain.

Neal

SirMike1983 

Hmm those all seem to note 3/32 as their size- would a 3/32 cog fit a standard stock chain (1/8)? I assumed they were different, but if I'm wrong about this- let me know.

https://sheldonbrown.com/harris/sturm...html#sprockets

I was looking in particular at the solid 22 tooth, or perhaps the 20 tooth. Would those fit the stock set up? I assumed not at first because I didn't think 3/32 and 1/8 would interchange.

wahoonc

Mike the 3/32" Nexus cogs will fit 1/8" chain. Depending on what your bike came with stock, FWIW my 1972 Superbe came with a 17t, you may have to lengthen the chain 3-5 links. My wife's bike has a pretty Chrome SRAM 22t cog. I am running a 20t on mine at the moment. On mine I had to lengthen the chain just a bit, but now that I have I can swap back and forth with no problems. The 18t sits further back in the stays is all.

Aaron

Pompiere

YOu can put a 1/8 inch chain on a 3/32 cog. The teeth are the same spacing, they are just .031" thinner. You may need to add a few links for the chain to reach around the larger cog.

SirMike1983 

Interesting- thank you for the tips.

I've never actually opened a chain up before (oddly enough I've never had to), is adding links an easy task?

Or is it easier to just load up a new 1/8 chain? (I guess you'd take the guard off and then slide it on).

Sheldon Brown

Everything works with 1/8" chain, 'cause it's wider.

3/32" chain only works with the thin sprockets. You have to use 1/8" chain because of the chainwheel in front, so that's not a concern.

You will nee a new chain, though, because your original chain won't be long enough. Going from 18 to 22 means you need to move the axle forward by 1/2" (12.7 mm) and you probably don't have enough room in the dropout slot for that.

Sheldon "1/8 Inch Per Tooth" Brown

SirMike1983 

Ah well a new chain it is then- if I order the SRAM/Sachs 1/8 Nickel chain from Harris will it come ready to fit the larger cog? My chain is getting long in the tooth (I'm sorry I couldn't resist) anyway, so it was a coming expense either way.

apw55

Most of your mechanical questions seem to have been answered except for how difficult it is to replace a chain. With a chain tool, it’s pretty easy. Most bike shops carry them and they are not expensive. They normally come with instructions and often the bike shop staff will give you some pointers. If not, I’m sure you can find advice on Sheldon Brown’s website or the Park Tool site.

On the other hand, not much input has been provided regarding the size of cog to use. This is difficult because the answer can vary dramatically from rider to rider. I live in a mountainous area but tend to ride my 3 speed bikes on routes that I would describe as hilly. A number of articles and forum threads that I’ve read recommended cogs in the 22 to 24 tooth range but I’ve found myself to be quite happy with a 19.

With only 3 speeds available, compromise is necessary. I find that I prefer to find the cog that allows a comfortable 3rd gear cruising speed and then suffer up the couple of short hills that I must climb to get home.

If you haven’t stumbled across it already, you might want to look at the gear calculator on Sheldon’s site. I find mph at a specific rpm to be most meaningful but other find gear inches and the like to be helpful.

My guess is that you’ll probably want to experiment with more than one size.

Regards,
Alan

nlerner

Mike, whether or not the chain is the correct length out of the box, I do advise investing in a chain tool. You'll need it to push a rivet out to shorten the chain or push a rivet in if you add links. My Cyclo-brand chain tool broke recently after something like 30 years of service, so I bought a Park CT-3 model. It's a beautiful thing, and unlike my previous one, it's set up so I can't push a rivet completely out of the chain (which is very handy).

Neal

Sierra

I live in the rolling countryside of South Central Wisconsin. My standard practice is to replace the cogs on my S-A 3 speeds with a 22t. As Alan noted, it is going to be subjective, but I find that the 22t cog puts the ratios in a nice usable range for a tourist type bike with an upright riding position in rolling terrain. I used to be able to buy the S-A cogs at a local bike shop, but they are not available there any more. I recently bought some on ebay, but they are thinner than the S-A originals, probably meant for 3/32" chain. They will work though, and they are steel, so wear will not be an issue. Harris probably still sells the S-A cogs.

SirMike1983 

Ah yes- I'll end up getting a chain tool too since it's probably a good thing to have on hand. I've heard decent reviews about the Park brand "Shop Tool" chain tool. Any comments on those?

The 22 tooth cog sounds about right for around here then- it's a pretty "up and down" type area near my apartment.

wahoonc

You won't go wrong with the any Park tool. I would get a 20t and a 22t just to be sure. I have my Superbe set up to run both, with the 22t the axle sits a bit further back in the stays. FWIW I have never bought a chain that fit just right, I have always had to shorten or lengthen them. Also if you are a cheapskate and buy your chains at WM get two...everything they sell is on the short side...

Aaron

Sheldon Brown

It will be plenty long. You always need to cut down a new chain to
fit a particular bike.

All the best,

Sheldon

SirMike1983 

Ok- the chain tool is a good idea then. Does anyone here use the Park CT-3 model on 1/8 inch chain? Or does that work only for the smaller chains?

apw55

I've used the CT-3 on 1/8" chains and it works just fine. In fact, so far I've only used it on 1/8" chains. With a little luck, I'll be using on a 3/32" chain this evening.

Regards,
Alan

nlerner

+1. Heck, you could probably use it effectively to do some dental work, too.

Neal

SirMike1983 

Put in an order for 2 Sachs Nickel 1/8 chains and a Park CT 3 today- I'll get them shipped to CT so I can get them at my family's place in CT while on vacation. I've got a DL1 up there that could use hill help too, so I figured I may as well swap both the Sports and the DL1 at once. That'll give me a week or so try the rig out in some tough up and down country in the Litchfield hills.

SirMike1983 

Update:

I've swapped cogs and chains on both the DL1 and the Sports. The Park CT3 chain tool is a nice thing to have and it worked on all the chains without a problem. The Sachs chains are quite nice and very smooth. They came with a nice little coating of factory lubrication.

Has anyone else noticed this:

On the Sports I reset the rear wheel in the dropout. Originally the thing came with the rear wheel quite close to the mouth of the dropout. When I put the new chain and new cog on, I moved the wheel more towards the center-rear of the dropout. After taking it out last night on a test run I noticed the ride was a lot softer- would moving the wheel a little deeper in dropout have caused this? Would the slightly longer wheel base have caused this?

I have no complaints about the softer ride at all (it's actually quite nice), so long as there isn't anything wrong with having the wheel sit a little farther back than it did. It doesn't seem to rub on anything.

apw55

In experimenting with different cogs, I've ended up with the axle throughout the range of the dropouts with no adverse effect. On the other hand, I've never noticed any significant change in the ride quality either.

Out of curiosity, which size cog did you end up going with and how do you like it so far?

Regards,
Alan

mparker326

Softer ride feel could be the new chain.

Just curious, I've thought about swapping out the 18 cog on my Sports, but figured I'd leave well enough alone since the current setup is ok on all but one hill on my commute.

What were the steps in swapping out the cog? On a scale of 1-10 how hard/much of pain was it?

wahoonc

I would give it a .5 compared to a lot of things. I can swap a cog in less than 5 minutes if I don't have to add or subtract from the chain length. The cog is held on by a snap clip, small screwdriver will pop it off, pull the spacer (if it has one) pull the cog, add the cog replace the spacer, replace the spring clip, reinstall wheel, adjust gear cable and ride. I actually carry a spare cog when doing long trips to fine tune the ratios to the roads I am riding on. If I have a day or two of long flats and no hills, I will put a smaller cog on, if I am going to be in the hills put the larger one on.

Aaron

SirMike1983 

I'd give it a 3 or 4 for difficulty- the hard part is fitting the new chain length and getting the wheel back on the bike. Mine was actually somewhat difficult because I had to totally reset my tire generator on the back wheel- which actually sort of turned out to be a pain. The swap itself was quite easy- here is what I did.

First you take the wheel off of the bike in the normal fashion.

Second you clean up the rear cog that you want to take off

Third you have to locate the round spring that holds the cog on. It will look a bit like a giant keyring.

Fourth you sink a small flathead screwdriver under that ring and gently pull it up. It should eventually snap up on its own. If you have trouble, don't force it but rather work your way around the circle a bit and let the spring do the work for you as it comes up.

Fifth now that the ring is up the cog should be able to be pulled up. Notice the direction the cog faces- the cogs have a bit of a sunken or raised (depending on how you look at it) center. You may want to try to preserve this orientation with the new cog (center in or out) if your drivetrain was working fine before the swap. Also notice that the cog has three little nubs- they should line up with three little slots. Pull the cog straight up and off. It usually comes right off. If it is stubborn a little help from the flathead again may help you out. Be gentle with it again. Note that there is a spacer (or perhaps a couple of them depending on your set up) in the area. You should clean these and use them with the new cog. Usually you just end up putting them back in the position they were before, just with the new cog instead of the old.

Sixth get your new cog and put it on. Line up the nubs and slide it on. The spacers go back to their old positions too.

Seventh once you have all your parts back on, reset the spring clip and pop it back on. This may take a little bit of force if you use just your hands, but I've found that hands alone are all I need to do it. It pops right back on for me.

Eighth: clean up (if needed) and remove your old chain if you're using a new one. Once you are satisfied that the wheel work is ready to go, reload the wheel onto the bike. Load up the new chain per the instructions that came with the chain.


Save all your old parts if they are working.