[old white truck]

I was removing my chain to clean it. Something didn’t seem right in the area of the countershaft sprocket. I put my finger on the sprocket and I could wiggle it. I thought: “this can’t be good”.



I did my best to squint up through the various bike bits to look at the sprocket. The bolts between the sprocket and the sprocket holder plate were gone. Not only that – the holes between the pieces didn’t even line up. Now I was thinking: “Holy crap – did the bolts come out and allow things to twist around and mess up the lands/grooves in the end of the drive axle?”



Well, after removing the case cover I found that the previous owner had replaced the stock front sprocket with a 13 tooth PBI PRO sprocket. However, the sprocket holder plate was obviously not compatible with the sprocket because there was no way the two holes would line up while still mating up with the lands/grooves in the shaft. Also the holder was too long and its ends were being deformed by the chain links.



The previous owner evidently hoped to hold things in place with a giant circlip instead of the bolts. However, there was too much slop in this mechanism and that is why the sprocket was wiggling.



After removing the sprocket I found out that the lands and grooves in the end of the shaft were just fine (whew). However, the sprocket teeth were really worn on the back side and not worn at all on the front side.



I had already ordered a new o-ring chain and sprockets so this is was not a big problem. I was just wondering how he ever could have made this sprocket work? Is this a typical problem when changing gearing via the front sprocket?





The first photo below shows the sprocket as I found it, and the next is after I cleaned it up and put it back on for a second photo. The last picture shows how worn the back side is. Compare that to the front side where all the machining ridges are still completely in place with no wear at all.

 

[TW-Brian]

Great pictures! They make it easy to understand the problem that you discovered.



Are you sticking with a 13 tooth sprocket? You'll have to let us know how you are able to resolve this.

 

[Toyanvil]

Thats the lazy way to do, of course finding that big of a clip can't be easy.

 

[tinman tim]

I guess it could have been worse. He could have 'coated' the whole thing in a heavy bead of silicone. Ya know. For noise.

 

[Gerry]

My friend, that is the only way you are able to attach a sprocket smaller than 14 tooth. When you go that small, the overall sprocket diameter (see picture 1. Does hole in plate look to be lined-up with sprocket) is so reduced that there is not enough room for the chain AND the bolts. Should you use the bolts, because of the reduced diameter, the chain will ride up on the bolts and not fully nest on the sprocket. The previous owner did nothing wrong. Going to a small diameter sprocket mandates this type of clip connection. I know as I purchased a 12 tooth and chose not to use it. ............ Gerry

 

[Rainman]

My friend, that is the only way you are able to attach a sprocket smaller than 14 tooth. When you go that small, the overall sprocket diameter (see picture 1. Does hole in plate look to be lined-up with sprocket) is so reduced that there is not enough room for the chain AND the bolts. Should you use the bolts, because of the reduced diameter, the chain will ride up on the bolts and not fully nest on the sprocket. The previous owner did nothing wrong. Going to a small diameter sprocket mandates this type of clip connection. I know as I purchased a 12 tooth and chose not to use it. ............ Gerry

Right on Gerry.



When I bought my used bike, the previous owner had done the same thing, but he just had a circlip holding on the sprocket. Worked just fine. I eventually replaced the sprocket and I sprung for a new holder as well.

 

[old white truck]

My friend, that is the only way you are able to attach a sprocket smaller than 14 tooth. When you go that small, the overall sprocket diameter (see picture 1. Does hole in plate look to be lined-up with sprocket) is so reduced that there is not enough room for the chain AND the bolts. Should you use the bolts, because of the reduced diameter, the chain will ride up on the bolts and not fully nest on the sprocket. The previous owner did nothing wrong. Going to a small diameter sprocket mandates this type of clip connection. I know as I purchased a 12 tooth and chose not to use it. ............ Gerry

Ahhh. I was wondering if there were any other alternatives. However, I am guessing there is a better way to add the circlip? The sprocket was very wobbly due to all the slop in the connection and there was significant wear on one side of the sprocket and zero wear on the other side. This seems like a recipe for premature chain failure. Does everyone with a 13 tooth or smaller have a wobbly sprocket and uneven wear?



Maybe a thicker washer/holder or a thicker circlip would prevent this?



Thanks for the insight Gerry!

Are you sticking with a 13 tooth sprocket? You'll have to let us know how you are able to resolve this.

Hi Brian,



No, I am installing a new 14 tooth. However, I was curious to see what people thought of this situation in case I ever had the inclination to go to a smaller sprocket in the future.

 

[tw200sgp]

I don't think the wear is that excessive. Nothing wrong with that setup - there's not particular reason for a front sprocket to be dead tight on the front shaft - a bit of lateral movement allows it to compensate for chain movements. The material in the front shaft should be much harder than the sprocket spline which will wear and be replaced in due course anyways.

 

[Rainman]

I don't think the wear is that excessive. Nothing wrong with that setup - there's not particular reason for a front sprocket to be dead tight on the front shaft - a bit of lateral movement allows it to compensate for chain movements. The material in the front shaft should be much harder than the sprocket spline which will wear and be replaced in due course anyways.

I agree. Even with the stock setup of a sprocket and sprocket holder, there is some play. I assume the play is needed so the chain doesn't bind on the sprockets due to minimal misalignments.

 

[RockyTFS]

The previous owner evidently hoped to hold things in place with a giant circlip instead of the bolts. However, there was too much slop in this mechanism and that is why the sprocket was wiggling.

I have a 13 from a different manufacturer; it does not have the the ears on the plate nor the threaded holes. However, it does wiggle quite a bit and I was assured by the dealer tech (whom I know and trust) that this is normal. It needs to float a bit. To me, your wear pattern doesn't seem abnormal at all and the sprocket looks good for many more miles. My original OEM sprocket did use small bolts to hold the plate on, but the plate was smaller so no interference. It still had some wiggle to it.



I would just grind off the ears unless you are changing ratios.

 

[Toyanvil]

I would file the holes in the holder to line up with a round file and install button head allen bolts, you could even file the bolts a little to clear the chain and not use the clip. The fact that the sprocket is only wearing on one side means it is not in the right spot. Your set-up will work the way it is but will wear out faster. I think I would install a 14 and a larger back sprocket. The rule of thumb is 1 = 3 changing 1 in the front is close to 3 in the back.

 

[Gerry]

Boy, we are certainly expending a lot of mental energy to reinvent the wheel. The clip works. If someone is into some extra effort see what can be done with this to afford even more gearing options. Gerry

14/15 tooth and 50/55. Same length chain. Takes more time to get my tools out of the bag than rolling over to the adjacent gear set. Certainly not for everyone, but has worked very well for me. Chains and sprockets are very affordable I don't begrudge accelerated wear when I get versatility. To date, the 'wear rate' has been a non-issue.

 

[Gerry]

I certainly did not mean to have this thread fall mute. I do like my moments in the 'spot-light' but my intent here was to suggest that instead of belaboring the benefits of clip over bolts, as both seem to work. We can explore and expand upon something that is directly related to sprocket attachment. Many folks fret and fuss over getting the 'BEST' gear ratio. Some folks here have expanded their options by going with two rear sprockets and seem generally pleased with the end result. I think only one of us has installed a dual primary and dual rears. As mentioned, the end result is pretty nice, likely fine for many of us. Imagine what it would be if instead of a 14/15 front, you could do a 12 or 13/15 front and a 48/52 rear. Yes, I know, small sprockets wear faster and stress the chain more, but as stated before, TW chains and sprockets are most affordable.



My hope here is to have another innovator take the above working concept and see if another adapter could be created as to allow more options. Gerry

 

[admiral]

Few months back, I changed both front and rear sprockets dut to excessive wear. When I changed the front, I didn't give it a thought that it was loose. Just thought that's the way it was suppose to be.

Generally, I've been very satisfied with the stock gearing for the terrain and places I ride, but I have a 55 rear tooth showing up at anytime (thanks to dr. procycle, ha ha). My plan is to copy you (mrgizmow) and darnold's dual rear sprocket (mine 50/55 combination). Printed off some copies of the photo's to study. Hopefully within the week it will show up. I'm a little uncertain whether I'll pursue a dual front sprocket setup, but I'll make that determination after some use with the dual rear. But I've been studying mrgizmow's dual front for quite some time. My thought of a dual front, would be to keep both dual front sprokets stock, with only the rear's different. Anyway, I hope to have the dual rear setup ready for testing this weekend.

 

[TW-Brian]

Hi Admiral,



I have been running a dual rear sprocket setup for quite some time now. I started with a 47/50 which allows the use of the stock length chain for both sprockets. In order to get the clearance that I needed, I had to mount the non-stock (47) sprocket on the inside, with the recess on that sprocket facing the wheel. See picture below:

I am now running a 47/55 rear sprocket combination (sorry, but I don't have a pictures of this setup). This requires that I add/delete a short segment of chain when I want to change sprockets. This is not a huge task, but it is time consuming and the spring clips on the master links only seem to survive for a few of these on/off cycles before they break (this could be my problem). The benefit of Gizmow's dual front sprocket setup would be to allow for a wider spread between rear sprockets without having to add/delete links.



Since the slight misalignment of the chain when using dual rear sprockets is (in my opinion) a non-issue, I am curious why are you considering using dual front sprockets of the same size?

 

[admiral]

Hey Brian,



As you mention, I'm really hoping I don't need or require a dual front sprocket as it appears unusual wear is a non-issue. However, should I need to add a front sprocket in the future, my reason for keeping the same size front would be that in my case, all the gearing changes I require can be accomplished with the rear sprockets. I'm a bit more of a mountain man rider when it comes to my TW riding, and I believe the stock setup satisfies 99% of my needs just fine. However, I've found myself in a couple of pickles or potential pickles where I think a 55t would have helped a bit more. Nothing I haven't been able to get out of, but now is as good of a time to test a 55t. I think I'll need the 55t more when I ride with Ron in Boise.

I also ordered an extra o-ring master link in case I need to add or remove links as you mentioned above. Glad you mentioned it just in case someone else is thinking about a dual sprocket setup.



Bad part so far is, my parts didn't come in today. Worked an early shift just in case they came in so I could fiddle around some out in the shop with the new sprocket.



Thanks for posting the photo. I tried to find others photo's so I could compare and could only find darnolds and mrgizmow's. Now I have another view.

 

[TW-Brian]

With all due credit to darnold87, the following illustration is key to the dual rear sprocket setup:

Just so you are forewarned, it took me at least three attempts before I got a combination of sprockets/nuts/washers stackup combinations before I found one that provided sufficient clearance between the sprockets for the chain, and between the outside sprocket and the swingarm. I am pretty sure that I had to move the washer from between the inner sprocket and the axle hub and add it in between the two sprockets. Either that, or I just deleted it entirely. Sorry, but my CRS is kicking in (Can't Remember S _ _t).



Like most of my home projects, this one involved multiple trips to the hardware store. This was not a big deal for me, but judging from your videos I would guess that it is a bit of a hike for you to get to a hardware store. Since you don't have your sprockets yet, you may want to make a pre-emptive strike on the hardware store for sufficient (i.e., plenty/extra) bolts, nuts and washers before you launch into the teardown and re-assembly. It may save you from getting midway into things and realizing that you need just a few more bits and pieces.



Have fun and don't hesitate to ask questions if you get stuck.

 

[B-dub]

I also put a washer with the nut between the two sprockets because I wasn't satisfied with the chain rubbing on the other sprocket. The addition of the washer provided enough clearance, and the combination still fit within the stock chain guard. I ran that setup (single front, dual rear) on my 1,000 mile trip this summer with no problems. Thanks to all who've contributed to this awesome mod, I mean farkle. Oh, and for OWT, my front sprocket is not a tight fit on the output shaft either. I'm pretty sure that is by design.

 

[TW-Brian]

Thanks, you're right B-dub. Since it sounds like Admiral will be using an o-ring chain, he will need some extra clearance between the sprockets and will probably need both the nut and a washer between the sprockets.

 

[Gerry]

At this point, we still need deep thinkers with a mill or lathe to see if an adapter can be easily fabricated to carry two front sprockets. My first one was made by 'hand' with grinding stones and a drill press but it is unlikely others will enjoy doing the same.



As stated, the rear sprocket mis-alignment is generally considered a "non-issue". Putting two sprockets in front involves more work than the rear, but it's certainly not rocket science requiring special tools. If you move in this direction, it behooves to think 14/15 teeth. Nothing is lost, and much is to gain.



Some 'tricks' that I implemented when I first put together the dual rear. I ground (forward/rearward) the slots for the axle just a "bit" to afford more working room. As well, I deepened a couple of notches on the chain tension cam. I was wanting to make sure I had enough chain slack to easily move the chain from one combination to another. Not sure my chain is stock anymore, but for my 14/15 and 50/55 I do not need extra links. The added front sprocket can only (my opinion) be added to the inside (engine side) of the original.