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Going to a 7-Speed Cassette from a 6-Speed Freewheel

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Going to a 7-Speed Cassette from a 6-Speed Freewheel

Old 05-24-23, 10:56 PM
  #26  
Schweinhund
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Originally Posted by Kontact
For bolt on hubs on a crummy frame, why not make the dropouts wide? Makes it easier to assemble.
That is so funny and true.
Brings to mind a kerfuffle I caused on Slack because I had the temerity to admit and even tell other people that 12v impact wrenches are just as effective at tightening axel nuts way past spec as 18/20v impact drivers.
Probably more so.
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Old 05-25-23, 09:19 AM
  #27  
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I got the new wheels on yesterday. The gears seem to shift fine.
I'm still a little confused by the rear axle dimension. The 130mm rear wheel went on okay, but there was a little resistance. Could the original 126mm wheel have been right and the frame sloppily set up (too wide)?



Last edited by WT160; 05-25-23 at 05:33 PM. Reason: grammar
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Old 05-25-23, 09:38 AM
  #28  
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It doesn't matter when it comes to old vintage crap.

Everything is eyeballed to make it work, when the rider is happy, the job is done.

That's how they built everything in the last century.

If I wanted something that was NASA precision, I'd buy a S-works.
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Old 05-25-23, 10:29 AM
  #29  
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Your stays are pretty "spindly", so I wouldn't think 4mm would offer much resistance.
How did you measure?

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Old 05-25-23, 12:53 PM
  #30  
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I measured in between, as you've shown. I'm smack on 130mm.
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Old 05-25-23, 05:06 PM
  #31  
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Originally Posted by WT160
I measured in between, as you've shown. I'm smack on 130mm.
That is a rather cool looking bike.

One issue that you "might possibly" run into is the chain not wanting to come back off the smallest cog because of clearance issues.
That can usually be easily remedied by putting a thin washer under the lock nut of the DS cone.
I think it tends to manifest itself, it's when going to a smaller end cog than "stock". Like 14T to 12T.
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Old 06-01-23, 04:34 AM
  #32  
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I was back at this, riding the bike a few days ago, trying to fine tune. It looks like seven speeds isn't going to work well. The geometry of the chain is angled too far out on the outer cogs. I can't get it adjusted so that it doesn't rub. Back to six speeds, it seems.
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Old 06-01-23, 06:18 PM
  #33  
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Originally Posted by WT160
I was back at this, riding the bike a few days ago, trying to fine tune. It looks like seven speeds isn't going to work well. The geometry of the chain is angled too far out on the outer cogs. I can't get it adjusted so that it doesn't rub. Back to six speeds, it seems.
Are you not trimming the FD when you shift the rear to the far ends? I've never had a downtube friction bike rub.
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Old 06-01-23, 07:53 PM
  #34  
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Originally Posted by Kontact
Are you not trimming the FD when you shift the rear to the far ends? I've never had a downtube friction bike rub.
It can happen; short chainstays and wide chainring jump exacerbate the issue.
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Old 06-01-23, 09:37 PM
  #35  
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Originally Posted by JohnDThompson
It can happen; short chainstays and wide chainring jump exacerbate the issue.
Given what we know about the OPs bike, I doubt some radical gear steps are involved.
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Old 06-02-23, 01:24 AM
  #36  
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Originally Posted by JohnDThompson
It can happen; short chainstays and wide chainring jump exacerbate the issue.
i ran into a similar problem when i tried a 7 sp suntour frewwheel on my '82 trek... the freewheel cleared the frame,but as soon as the chain shifted to the small cog, it began rubbing the dropout.... the venerable old trek remains a 6 speed.
i didn't try putting a narrower chain on... it seemed that it wouldn't give enough clearance anyway, and i'm not about to tear up the Imron paint.

Last edited by maddog34; 06-02-23 at 01:47 AM.
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Old 06-02-23, 01:30 AM
  #37  
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Originally Posted by WT160
I was back at this, riding the bike a few days ago, trying to fine tune. It looks like seven speeds isn't going to work well. The geometry of the chain is angled too far out on the outer cogs. I can't get it adjusted so that it doesn't rub. Back to six speeds, it seems.
you can shift the axle over about 2mm with some spacer/washer trickery, then redish the wheel to compensate... but if you're like me,you looked at the "advantage" of one more choice, and decided to just ride the bike as is.

and 6 sp. freewheels are just about free in my Co-op, so there is that factor...
Nice bike, BTW .. the bike i had just before getting the Trek was a Puch touring bike.. that frame was Copper plated, and the paint was trashed, so... Paint remover then Steel wool had it shining like a new penny.. I clear coated it after painting the Lugs black and adding a gold pinstripe around them...

Last edited by maddog34; 06-02-23 at 01:37 AM.
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Old 06-03-23, 04:32 AM
  #38  
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Originally Posted by Kontact
Are you not trimming the FD when you shift the rear to the far ends? I've never had a downtube friction bike rub.
Yes, I am. The main issue is the geometry across the smallest cog while on the small chain ring, as the chain rubs on the large chain ring at that angle.
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Old 06-03-23, 08:29 AM
  #39  
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Originally Posted by WT160
Yes, I am. The main issue is the geometry across the smallest cog while on the small chain ring, as the chain rubs on the large chain ring at that angle.
That's normal. We don't use that gear combination under normal circumstances, and if you have to use it, the rubbing noise isn't going to break anything.
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Old 06-03-23, 01:40 PM
  #40  
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Originally Posted by WT160
Yes, I am. The main issue is the geometry across the smallest cog while on the small chain ring, as the chain rubs on the large chain ring at that angle.
The small-small combination is a bad choice for 3 reasons:
1. There is a large angle in the chain, which is more stressful, as well as creating the problem you are having.
2. It is a relatively high gear with the minimum number of total teeth engaged, which increases chain and small cog wear.
3. There are one or two large chain combinations that duplicate or bracket that gear ratio and offer both lower wear and better chainline.

Last edited by cny-bikeman; 06-03-23 at 01:44 PM.
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