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Modern RD on Old Bike with Friction Shifters.

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Modern RD on Old Bike with Friction Shifters.

Old 04-28-20, 04:18 PM
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prighello
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Modern RD on Old Bike with Friction Shifters.

Hello,

I have searched for answers to this but cannot find one definitively. I have a 1985 Schwinn Worldsport roadbike which has a Shimano Light Action groupset. It has stem mounted friction shifters that click but are not indexed. The freewheel is 7 cogs and the crankset has 2. My rear derailleur broke and I need to replace it. I am a little hard up for cash as I was recently laidoff due to Covid 19. I am trying to keep this beast running til I am gainfully employed again; it is my outlet for health and sanity right now!

I went to the LBS and they told me I need to replace the RD and shifters. Which means upgrading to indexing. I "think" this is not quite true. That all I need to do is replace the RD. My understanding is that friction shifters are pretty forgiving and RD's don't care how many gears you have? What I'd like to do is use a modern RD since they don't make mine any more. Can I use a something like a Shimano Claris 8 speed or Sora 9 speed RD with a 7 speed freewheel and friction shifter? Please let me know and thank you for the help.

Last edited by prighello; 04-28-20 at 04:37 PM.
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Old 04-28-20, 04:22 PM
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You DO NOT need to replace the shifters.
Anything from a low cost Shimano Tourney will work.
Do go too far up the food chain. As the number of speeds increases, the cage gets narrower.
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Old 04-28-20, 04:22 PM
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Yes, friction shifters whatever brand work with whatever brand RD. Don't go higher than a 9 speed RD or you won't be able to set the stops right and your chain might slip off the cogs.
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Old 04-28-20, 04:27 PM
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Thank you for the swift replies Bill and Dwillems! So I should try to get a 7 speed RD for the best match? I ask because it looks like that is the Tourney one and it looks like it is made of plastic. I want to make sure I don't get something too cheap that is prone to failure in a short period of time.
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Old 04-28-20, 04:27 PM
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Friction shifters on a mid-80s road bike? Basically any lower-end RD will likely work. You probably want to avoid 10/11/12-speed stuff because the cage might be too narrow for the chain. If you're unsure, the safe bet is an entry-level MTB derailleur like an Altus M310 or Acera M360; they'll work great with almost any friction drivetrain from that era.
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Old 04-28-20, 04:32 PM
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A Claris rear derailleur would be ideal for this application. Designed for 8 speeds, it can easily handle the width of chain you need. Good quality, it would last for years. No need for an indexed shifter
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Old 04-28-20, 04:34 PM
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This is what I thought. One last question, how do I know what cage length to get?
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Old 04-28-20, 04:46 PM
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Originally Posted by prighello View Post
This is what I thought. One last question, how do I know what cage length to get?
Don't know, did you include information about your freewheel and chainring cog counts?
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Old 04-28-20, 04:47 PM
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Originally Posted by prighello View Post
This is what I thought. One last question, how do I know what cage length to get?
It's a matter of chain wrap, which is the total amount of chain that the rear derailleur needs to take up between the small-small and big-big gear combos. For example, if you had a 52-36 crankset and an 11-32 cassette, the chain wrap that you need is (52-36)+(32-11) = 37 total teeth of wrap. Shimano tends to list wrap in their specs as "total capacity." You'll want to get a derailleur that has at least as much wrap as your drivetrain requires. "Too much" wrap isn't really an issue.

Longer-cage derailleurs have more wrap than shorter-cage derailleurs.
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Old 04-28-20, 04:54 PM
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IIRC the light action (which was underated) was short chage...... so almost anything will work..... and if $$ are tight you might see if there is a bike coop close or a different LBS that deals with older bikes... you might be able to get a used one really cheap
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Old 04-28-20, 05:08 PM
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IIRC my World Sport had 52/39 and 12/25 or 12/28 freewheel
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Old 04-28-20, 05:11 PM
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Okay, so the Crankset is 52/40 and the freewheel is 28-11. So, based upon the formula above, the slack would need to be 29. So, it looks like a Shimano Claris shortcage would work since the total capacity is 37 teeth. Thank you folks for all the help. Also, will check out a coop as it would be cool to just replace it with another light action rd.
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Old 04-28-20, 05:27 PM
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Once you get 10 posts, could you post a picture of your bike? An ice blue 85 WS was my parents' HS graduation gift to me and I rode that bike through college, law school, and commuted to my first job on it. I wish I still had it.
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Old 04-28-20, 06:11 PM
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I can send you a rear derailleur. Whereabouts are you located?

Cheers
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Old 04-28-20, 06:13 PM
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Originally Posted by caloso View Post
Once you get 10 posts, could you post a picture of your bike? An ice blue 85 WS was my parents' HS graduation gift to me and I rode that bike through college, law school, and commuted to my first job on it. I wish I still had it.
For sure, I was going to PM you to get your email and just send a pic but I guess I need 10 posts to do that as well.
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Old 04-28-20, 06:16 PM
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Originally Posted by Miele Man View Post
I can send you a rear derailleur. Whereabouts are you located?

Cheers
Wow! Thanks Miele Man. I am in Arizona USA. It looks like you pm'd me but I need 10 posts to see it. I will get there. I suppose I'll start an introduction thread to hit the needed post count.Thank you for your kind offer!
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Old 04-28-20, 06:54 PM
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Originally Posted by prighello View Post
Wow! Thanks Miele Man. I am in Arizona USA. It looks like you pm'd me but I need 10 posts to see it. I will get there. I suppose I'll start an introduction thread to hit the needed post count.Thank you for your kind offer!
What the heck. If you don't waiting for it to arrive I'll send one out to you as soon as you're able to send me your address. I'm in South Central Ontario Canada so it'd take about a week to get to you. I think you can get my email address by clicking on my user name.

Good luck and cheers
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Old 04-28-20, 07:08 PM
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Yes, shimano Claris is their entry budget grade. I have it on my bike and love it.

Length depends on your gears. The bigger the difference in your gears the bigger the cage. So if you have 3 gears up front get a long cage. 1 gear up front you might be ok with a short cage. please don't take my weird though since I'm not that experienced with this part. Please wait for someone to comment or do a search. Park tool and shimano's website has good info on it.
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Old 04-28-20, 07:24 PM
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Originally Posted by Dwillems26 View Post
Yes, shimano Claris is their entry budget grade. I have it on my bike and love it.

Length depends on your gears. The bigger the difference in your gears the bigger the cage. So if you have 3 gears up front get a long cage. 1 gear up front you might be ok with a short cage. please don't take my weird though since I'm not that experienced with this part. Please wait for someone to comment or do a search. Park tool and shimano's website has good info on it.
Thanks for the info and have a great day!
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Old 04-28-20, 07:36 PM
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Originally Posted by caloso View Post
Once you get 10 posts, could you post a picture of your bike? An ice blue 85 WS was my parents' HS graduation gift to me and I rode that bike through college, law school, and commuted to my first job on it. I wish I still had it.
Here yeah go. Missing original bars, seat, and break levers. Wish I had them but the original owner swapped them and didn't save them. I've been riding this bike for three years now and love it.


Worldsport
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Old 04-28-20, 07:39 PM
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Can you post another image but from the drive side?

Cheers
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Old 04-28-20, 07:44 PM
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Originally Posted by Miele Man View Post
Can you post another image but from the drive side?

Cheers
For sure, please see below.
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Old 04-28-20, 07:53 PM
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Okay and thanks. I'm pretty sure I have a Light Action rear derailleur in my rear derailleurs box. I'll get it into the post for you tomorrow.

Cheers

Edit. I looked through m y spare parts and I do have a Light Action rear derailleur. I'll send it out tomorrow.

Cheers

Last edited by Miele Man; 04-28-20 at 09:47 PM. Reason: Added comment
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Old 04-29-20, 07:37 AM
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Originally Posted by prighello View Post
One last question, how do I know what cage length to get?
1) If you haven't changed the gearing, get one similar in length to the original unit.

2) When in doubt, go longer. There is no penalty besides a few grams extra weight in having a longer cage than is necessary. But too short a cage can mean either not being able to tension the chain properly over the full range of gears, or damaging the derailleur by exceeding its range.
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Old 04-29-20, 10:12 AM
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Originally Posted by Miele Man View Post
Okay and thanks. I'm pretty sure I have a Light Action rear derailleur in my rear derailleurs box. I'll get it into the post for you tomorrow.

Cheers

Edit. I looked through m y spare parts and I do have a Light Action rear derailleur. I'll send it out tomorrow.

Cheers
Awesome! Thank you so much Miele Man, I owe you one
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