Puch Prima - gearing and brakes

[cbrcbr]

Hi there, I am new to the forum having just bought a Puch Prima (1986 - I think - generally in very good condition), and am after some advice re gearing and rear wheel compatibility.
The bike has 42/52 chainrings and 14/24, 6 speed freewheel. I will use it for running around locally and occassionally on my 12 mile commute. I have a fully geared touring bike in the shed as well so am quite specific about the gearing I can get away with on the Puch, as my local roads are relatively flat and I only have one short hill on my commute. I would like a single chainring (I like the clean uncluttered lines of a single chainring), and don't really want any revisions to the bike to snowball money wise.
I am after a gear range of between 1:1.9, and 1:4.0. I nearly acheive this by keeping the 52 chainring, and installing a 14/28 freewheel, but may replace the chainring with a 56 tooth chainring. I assume though that if I do go with the 56 it will be for a 9 or 10 speed, and will be designed for a slimmer chain. Will my 6 speed chain run okay on the 56 chainring?

I would also like to upgrade the wheels, but only to allow me to fit 25mm tyres (the bike currently has 622x16 alloy rims). Therefore I guess my options are: stick with current wheels (they look a bit wide and flatten out the current 25mm tyres); new wheels, (but I am struggling to find good wheels that take a freewheel); new road bike wheels and cassette (not freewheel compatible, OLN probably not suitable, and then into additional drivetrain revisions at more cost); or put new rims on my existing hubs. Does anyone have any thoughts or experiences of something similar?

I also want to upgrade the brakes, and wonder if anyone has advice on which calipers to go for, that do or don't involve replacement levers.

Thanks for your advice.

 

[mattsccm]

Re:

I think that this won't be easy.
1. A 56 t chainring is a whopper and very rare. Generally used in the old days by those wanting a super high gear for pan flat time trials before people decided that spinning a lower gear was good. You can achieve the same top gear by using smaller rear sprocket's, maybe a 12, with more flexibility and less cost and that coupled with a distinct lack of need for something like a 56/12 means that a 56 will be hard to find.
2.Any idea of the BCD of the current chainrings as you will have to finds a rare size in a specific BCD. That's going to make life harder.
I bet you could do things cheaper by buying freewheel with something like a 12 t sprocket and keeping your current chainset without the inner ring. Chainrings cost more than freewheels.
Some people will question your choice of high gears, that's up to you. A 56/12 would be higher than the pros use in most circumstances. All I am questioning is how you go about it. A quick play with a gear calculation programme, try Sheldon Brown will give you an idea of what can be achieved by playing with the back end of the transmission.

 

[cbrcbr]

Re:

Thanks for the advice. My local bike shop has good value road wheels (shimano hub and mavic rims) with a 7 speed cassette (12/2 that they are sure will work, so I think I am going to go for that option. I will start there and see how everything else evolves over the next few weeks.