Lowering gear ratio on an old town bike

[8mph]

Hi, unfortunately I don't have the bike in question at hand and only have a few pics. As far as I recall it's 2 x 6 speed and 14 - 28t screw on freewheel. (friction shifters)

I'd quite like to fit smaller chain rings, rather than mess around with the freewheel. Here's a pic, if anyone fancies hazarding a guess as to the size BCD etc, thanks.

Fitting a different Crankset could be another option perhaps? Any advice appreciated

 

[Ming the Merciless]

Your main challenge may be the 3 bolt pattern. Is this your bike or someone else’s, and how much are they / you prepared to spend on it? Plus what’s the current size of the chain rings?

 

[Sharky]

Scroll down this link to the 3 bolt rings
https://www.sheldonbrown.com/cribsheet-bcd.html

 

[chris667]

Cottered cranks could very easily mean unreplaceable or unobtainable rings, especially in small sizes. If I was adamant that the rings had to be replaced, I would take the bottom bracket out and fit a cotterless axle. It might also mean that hockey stick had to go, which is a shame as it makes the bike more useful.

Being old and Italian theres even the possibility that it has an Italian BB. Definitely not something to mess with if it works.

Are you really sure you would rather not just replace the freewheel? Shimano "Megarange" freewheels go down to 34t and aren't expensive. You might need a new mech, but then again maybe not.

 

[Cycleops]

Too much trouble messing with the old 3 point rings which you may not find or changing to a cotterless BB and crankset. Easiest and simplest route to lower gears is the screw on free wheel if you have one but as it's a town bike does it have a hub gear? If it does then you will be forced to go with crank/BB change.

 

[8mph]

Your main challenge may be the 3 bolt pattern. Is this your bike or someone else’s, and how much are they / you prepared to spend on it? Plus what’s the current size of the chain rings?

It's a bike I bought, toured on then left with friends in Tunis, Tunisia, I'll be going back over in a weeks time. I'm not sure what size the chain rings are but the gearing is way too high, I believe it's a 52 / 42 Crankset and 28t at the back. I'm also unsure if the BB shell has an English thread.

 

[8mph]

Too much trouble messing with the old 3 point rings which you may not find or changing to a cotterless BB and crankset. Easiest and simplest route to lower gears is the screw on free wheel if you have one but as it's a town bike does it have a hub gear? If it does then you will be forced to go with crank/BB change.

It's a screw on freewheel but I'm not sure which brand, or if they go bigger than 28t, I couldn't source the right replacement on my last visit.

A third option would be a wheel build (I'd like to keep the steel rims). Last time I had work done on it the labour was very cheap.

 

[Cycleops]

So it's a single speed freewheel? If there's space between the rear dropouts (should be) you could just fit a freewheel block if you have horizontal drop outs to tension the chain. You could also add a derailleur so you could use all the available gears, thumb shifter on the bars. You might have to run a outer all the way to RD if there are no braze on guides and use zip ties.

 

[Ming the Merciless]

So it's a single speed freewheel?

It’s 2 x 6 as per OP.

 

[Ajax Bay]

So it's a single speed freewheel?

No. See OP.
Location of bike (and therefore need to source all necessary) makes this a challenge.
Something like this:
Amazon product ASIN B01NBXTH26View: https://www.amazon.co.uk/SPEED-EASIER-RANGE-FREEWHEEL-CASSETTE/dp/B01NBXTH26/ref=sr_1_11?keywords=shimano+6+speed+freewheel&qid=1692970295&sr=8-11

- you may say 'nervar' - will fit and give you 20% lower gear.
Probably new (2 links longer) chain required.
Freewheel will likely be a monster to shift. Long extension pipe required.
Chainrings very challenging to find. But measurement + Sheldon (link from @Sharky ) will tell you BCD, fwiw.

 

[8mph]

So it's a single speed freewheel? If there's space between the rear dropouts (should be) you could just fit a freewheel block if you have horizontal drop outs to tension the chain. You could also add a derailleur so you could use all the available gears, thumb shifter on the bars. You might have to run a outer all the way to RD if there are no braze on guides and use zip ties.

It's a screw on freewheel, 6 speed, as far as I remember. A bike mechanic (who turned out to be a scooter mechanic) managed to destroy the Sachs rear mech but I found a replacement for about £2 that worked fine (parts are cheap). I also sourced a bigger block, which didn't fit.

Smaller steel chain rings would be my preferred option, if possible.

 

[Cycleops]

Unfortunately you're not going to find chainrings in that 3 point configuration in a smaller size so your best option is to replace it with a square taper BB and find a crank set with a smaller chainring of your choice, plenty on eBay.
The hard part will be removing those cotter pins, some helpful videos on YouTube and some advocate using an automotive press tool for ball joints.

 

[8mph]

Unfortunately you're not going to find chainrings in that 3 point configuration in a smaller size so your best option is to replace it with a square taper BB and find a crank set with a smaller chainring of your choice, plenty on eBay.
The hard part will be removing those cotter pins, some helpful videos on YouTube and some advocate using an automotive press tool for ball joints.

Thanks for the advice. I have a Crankset and BB. Do you think the BB shell will be English threaded?

Edit: the bike mechanic was a bit of a whizz with these cottered cranks, fixed mine on the pavement outside his shop.

 

[Cycleops]

Probably is English thread, I'm betting that Bianchi had nothing to do with that bike, bought in and put their sticker on it.

 

[8mph]

Probably is English thread, I'm betting that Bianchi had nothing to do with that bike, bought in and put their sticker on it.

Looks like the real deal to me (Bianchi Ledro). Nice ride too, once it's up to speed.