48 tooth sprocket

Submitted by PaulD on Fri, 09/30/2016 - 18:16

Hi,

I'm looking for a 48 tooth front sprocket in good condition for my 1950. Like attached. The teeth on mine are getting a bit too worn. I would like to find one of the same style but other suggestions for a non-original replacement also welcome. This is a rider and I have made other alterations.

thanks,

Paul

7 Comments

Submitted by bicyclecollector on Mon, 10/03/2016 - 05:54.

fairly common sprocket, should be an easy find locally on a parts bike

Submitted by Brian R. on Mon, 10/03/2016 - 08:58.

I rode motorcycles for many years, and the sprockets would wear to the point that the teeth were pointed and looked like waves on the ocean due to uneven wear. When I look at your sprocket, I can't see any problem with it. The space between the teeth still look fairly even and the tops look thick, not sharply pointed. Why not just continue to use it as-is?

Submitted by cruisersbylou on Mon, 10/03/2016 - 12:37.

I agree totally Brian the sprocket looks descent. Chrome is good. One has to ask himself how much are you gonna ride the steed? Just commenting.

Submitted by PaulD on Mon, 10/03/2016 - 18:09.

Thanks for the comments.

While the shape of the teeth look good there are some that are pretty badly chipped. I have had some issues lately with the chain coming off. I could see problems with the chain so I have replaced it now and so far so good but am concerned about the chips and a bit of side wear on the sprocket.

I am running it with a 3 speed hub and the front and back sprockets are not absolutely in line. The rear is further out by about 1/8". I didn't consider that to be much of an issue when I installed it over 5 years ago but am now wondering if I should try, if possible, to correct that. I don't think there is anything more I can do with the rear but maybe I can shim the front between the cone and the sprocket. I do ride it a lot but may consider looking for something else to be my daily rider instead.

I have two extra front sprockets. One is a 46 tooth and the other is a 44. I might be able to work with the 44 by changing the back to a 17 to keep approximately the same ratio. The 46 is dished and would solve my alignment problem if I mounted it backwards. I'm not really sure that going with a different combination or ratio would be all that noticable. The 48:18 has been good so I haven't tried changing it.

Submitted by william rudolph on Sat, 10/08/2016 - 23:09.

some 3 speed hubs         namely sturmey archer  had sprockets that were dished  try reversing the sprocket .  hope this helps william rudolph

Submitted by PaulD on Tue, 10/11/2016 - 18:18.

Thanks William,

I will go back through it all but I have the dished rear sprocket in the most favourable position. My recollection is that I did all I could with the rear sprocket short of using washers to relocate the hub and then dishing the rim. There is also a sprocket spacing washer on the Sturmey Archer which allows for a further 1/16" shift one way or the other. I'll double check its location but I don't think I missed that.

thanks, Paul

Submitted by T-Mar on Fri, 10/14/2016 - 06:55.

A chainline deviation of 1/8" from optimum should not be an issue, even with a stiff, 1/8" chain. Older, derailleur equipped bicycles dealt with it all the time.

Regardless, if necessary, it is possible to shim out a CCM one piece crankset. All you have to do is install a spacer of appropriate thickness between the chainwheel and dust cap. This will shift the crankarms and chain wheel to the drive side by the thickness of spacers installed. Most CCM one piece cranks have sufficient protruding thread oo the non-drive side to accommodate a 1/8"' shift.

The easiest way to make spacers is to grind the tab off of adjustable cone lockwashers, though they provide a relatively small bearing surface between the chainwheel and dust cap. For larger bearing surfaces you can procure large diameter washers from hardware stores, though you may have to enlarge the hole for them to fit over the crankarm. Alternately, you could remove the flange from some old dust caps, or fabricate them from some scrap metal of the apprpriate thickness.