1960 Peugeot PX10... Gravster!
- Thread starter zidortri
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.... so the lunatics have found each other 
That's one of the most interesting, pleasant and intense thread I've ever read on a vintage bike forum
Full of technical tips and info matetials - I really appreciated the input on Juy rear mechs as I have one to restore and which is a bit of a mystery as to how it works.
Also love the cultural references... And the humour that goes with it
I will spread a good word and recommend its reading to a few vintage lunatics acquaintances of mine.
So, next item in the Gravel's drivetrain assembly... the cassette.
Might seems odd at first to dwell on a set of cogs as it's quite straightforward - especially when it's related to a modern cassette, on a modern hub.
Indeed from a gear range and technical assembly there is no issue. No need to look for ages for that cog with the specific tooth count that is needed to bridge the gap between two cogs, and to make sure it has the right diameter to fit onto the freewheel at the specific position, with the right notch pattern or threads, etc... I guess whoever has ever worked on a Maillard freewheel will understand.
However on a project such as the Gravster, there is a different issue.
The target drivetrain is a 10-speed one and the frame was initially designed for a 5-speed one.
One might think that since the rear dropout spacing has been spread from 120mm to 130mm everything should be sorted... Well not exactly.
It is true indeed that the rear wheel can now slide without any effort into the dropout.
But unfortunately increasing the rear dropout spacing is not enough to allow a wider set of cogs to be used correctly. The rear stays - and especially the seat stay, kept their original shape near the hub axle. And in those days the part of the seatstays near axle were relatively straight if not slightly curved inside the space between the rear dropouts - that is closer to the spokes... and the cogs for the DS seatstay.
As a result, the first cog will be very - as in very very very, close to the bottom of the right seatstay. Which means that the chain is very likely to rub against that part of the right seatstay when it is on the first position cog.
Unless you take a few measures...
1. Use the smallest cog available - that's an 11t cog on a 10-speed cassette. That way the first position cog's radius will be minimal and will increase the distance between the top of the teeth and the seatstay.
It might seems a bit cumbersome or even too much of a constraint to use an 11t first positon cog - especially if one is already using a relatively high tooth count chainset, but that's extremely efficient - probably the best and easiest way to prevent the chain from rubbing against the seatstay.
2. Insert a 1mm washer at the end of the hub axle - on the Ds obviously. This will move the dropout - and the attached seatstay further away from the first position cog.
It might seem objectionable to proceed so and generate an off centered wheel but that 1mm imbalance still falls within the tolerance limitations. Not ideal but still OK.
3- use a chain as thin as possible to gain a few tenth of millimeter. Using an 11-speed chain will provide an additional 0.4mm clearance compared to a 10-speed chain.
None of these solutions is a silver bullet for chain rubbing against the DS seatstay. Nor are they fully satisfactory form a gear range usability, or structural or mechanical standpoints.
But the combination of these three simple measures will provide an easy option to run a 10-speed drivetrain on a frame designed and built with a 120mm rear dropout spacing.
Might seems odd at first to dwell on a set of cogs as it's quite straightforward - especially when it's related to a modern cassette, on a modern hub.
Indeed from a gear range and technical assembly there is no issue. No need to look for ages for that cog with the specific tooth count that is needed to bridge the gap between two cogs, and to make sure it has the right diameter to fit onto the freewheel at the specific position, with the right notch pattern or threads, etc... I guess whoever has ever worked on a Maillard freewheel will understand.
However on a project such as the Gravster, there is a different issue.
The target drivetrain is a 10-speed one and the frame was initially designed for a 5-speed one.
One might think that since the rear dropout spacing has been spread from 120mm to 130mm everything should be sorted... Well not exactly.
It is true indeed that the rear wheel can now slide without any effort into the dropout.
But unfortunately increasing the rear dropout spacing is not enough to allow a wider set of cogs to be used correctly. The rear stays - and especially the seat stay, kept their original shape near the hub axle. And in those days the part of the seatstays near axle were relatively straight if not slightly curved inside the space between the rear dropouts - that is closer to the spokes... and the cogs for the DS seatstay.
As a result, the first cog will be very - as in very very very, close to the bottom of the right seatstay. Which means that the chain is very likely to rub against that part of the right seatstay when it is on the first position cog.
Unless you take a few measures...
1. Use the smallest cog available - that's an 11t cog on a 10-speed cassette. That way the first position cog's radius will be minimal and will increase the distance between the top of the teeth and the seatstay.
It might seems a bit cumbersome or even too much of a constraint to use an 11t first positon cog - especially if one is already using a relatively high tooth count chainset, but that's extremely efficient - probably the best and easiest way to prevent the chain from rubbing against the seatstay.
2. Insert a 1mm washer at the end of the hub axle - on the Ds obviously. This will move the dropout - and the attached seatstay further away from the first position cog.
It might seem objectionable to proceed so and generate an off centered wheel but that 1mm imbalance still falls within the tolerance limitations. Not ideal but still OK.
3- use a chain as thin as possible to gain a few tenth of millimeter. Using an 11-speed chain will provide an additional 0.4mm clearance compared to a 10-speed chain.
None of these solutions is a silver bullet for chain rubbing against the DS seatstay. Nor are they fully satisfactory form a gear range usability, or structural or mechanical standpoints.
But the combination of these three simple measures will provide an easy option to run a 10-speed drivetrain on a frame designed and built with a 120mm rear dropout spacing.
Last edited:
Guinessisgoodforyou
rBotM Winner
Put a washer in as you say and then re dish the wheel.
That's a great idea indeed. Thanks 
The only thing is... I've never actually worked on wheels
A bit ashamed I confess...
Plus I don't have a jig...
But as one of the contributors put it recently on one of the best vintage bike topics I've read so far - that is "Early 50s La Gazelle - Eau-de-Nil
The Merlot Aftermath 
" obviously, "the most satisfying projects are those that give you an excuse to buy a new tool or two" (Bikemig, post #385).
So either I bring that wheel to my LBS or I get my hand on a jig and give it a go...
The only thing is... I've never actually worked on wheels
A bit ashamed I confess...
Plus I don't have a jig...
But as one of the contributors put it recently on one of the best vintage bike topics I've read so far - that is "Early 50s La Gazelle - Eau-de-Nil
The Merlot Aftermath " obviously, "the most satisfying projects are those that give you an excuse to buy a new tool or two" (Bikemig, post #385). So either I bring that wheel to my LBS or I get my hand on a jig and give it a go...
It's unfortunate that you can't fit the modern cassette. I've had no issues sticking 9-speed ones on 130mm hubs into my 1960s Bob Jackson or my 1950s Frannie.
Frannie's spacing is very tight, but no rubbing.
For 1mm washer I don't think I'd bother re-dishing. Even for 2+mm, if you bump the dropout spacing by moving the ds stay, that will cancel out the extra hub length & asymmetry, surely.
Frannie's spacing is very tight, but no rubbing.
Given that you'd have to slacken the spokes, re-dish, then tension, as if you were building it from scratch, yeah, a very good learning experience
For 1mm washer I don't think I'd bother re-dishing. Even for 2+mm, if you bump the dropout spacing by moving the ds stay, that will cancel out the extra hub length & asymmetry, surely.
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