Vintage bike modification

[taximan]

I have a 1972 Hugh Porter which I rarely use because regretfully the gearing is too high for me because of the hilly terrain, I am thinking about fitting a triple chainwheel and possibly converting from the present five speed to a six or seven speed mega-range freewheel. What would be involved to do this, but more importantly, would it spoil the bike

 

[raleighnut]

I have a 1972 Hugh Porter which I rarely use because regretfully the gearing is too high for me because of the hilly terrain, I am thinking about fitting a triple chainwheel and possibly converting from the present five speed to a six or seven speed mega-range freewheel. What would be involved to do this, but more importantly, would it spoil the bike

I'd convert BUT make sure you retain the old parts for a future 'period' resto (older bikes sell better, if you have to sell in the future, with 'original' kit on)

 

[biggs682]

@taximan a swap will involve the bottom bracket ,fr mechanism and poss rear mech plus the crank and cassette but if it make the bike useable then go for it and like @raleighnut says keep the old bits .

 

[midlife]

I'd turn it into an old style triple with a 5 speed wide ratio block so it still looks OK, stronglight do some retro looking looking cranks

Shaun

 

[velovoice]

@taximan a swap will involve the bottom bracket ,fr mechanism and poss rear mech plus the crank and cassette but if it make the bike useable then go for it and like @raleighnut says keep the old bits .

Plus possible reset of rear dropouts? They're likely to be 120 which may take a 6 speed freewheel but struggle with anything more. I've not done this myself but I'm sure expert advice will arrive shortly?

 

[arch684]

It,s your bike change it if you want but keep all the parts so you can change it back if you decide to sell it as a vintage bike

 

[alecstilleyedye]

keep it as is and then sell for best price once entries for next year's erioca britannica are open…

 

[mrandmrspoves]

Old bicycles are meant to be ridden so go ahead and convert - but as Raleighnut says keep the parts you swap. As to what needs to be done, probably not much. Assuming you have friction shifters they will probably cope with an extra gear or two - but your derailleurs might not. You may be able to drop to a smaller double up front (possibly just a chain ring) and a wider range rear block - if it will achieve a low enough gear for you.
So at best: swap front small chain ring (avoiding new bottom bracket and possibly new front derailleur)
Swap rear block (avoiding new rear wheel and you will avoid changing gear shifters too) The rear derailleur will probably need swapping as it is probably too short to accommodate lower gearing. You should change the chain if replacing rear block and front chainring.
Have fun!

 

[Deleted member 1258]

The simplest thing to do is to use a 6 speed block and convert to triple, the six speed block should just screw on and then just adjust the rear mech, though you might need more spacers on the rear axle. The triple conversion will need a replacement bottom bracket with a longer axle and you might need to change the front mech.

 

[Dogtrousers]

As @velovoice has mentioned if you want mega range (32T) sprockets at the rear you will probably need a freehub + cassette rather than a freewheel. These need wider dropouts. You can cold set (ie permanently bend) the frame or you can just spring (ie wrestle) the large wheel into the small dropouts. I have a bike on which I do this. It has Marathon+ tyres as this is no fun to do at the roadside with impatient people standing watching.

 

[raleighnut]

As @velovoice has mentioned if you want mega range (32T) sprockets at the rear you will probably need a freehub + cassette rather than a freewheel. These need wider dropouts. You can cold set (ie bend) the frame or you can just spring (ie wrestle) the large wheel into the small dropouts. I have a bike on which I do this. It has Marathon+ tyres as this is no fun to do at the roadside with impatient people standing watching.

I'd avoid trying to change axle width on the back. It should be pretty easy to end up with 28-28 gearing using a triple on the front (with a screw on freewheel)

 

[midlife]

You can get big sprockets on a 5 speed block

Shaun

 

[Dogtrousers]

You can get big sprockets on a 5 speed block

Oh, sorry. Ignore me.

Did I ever mention that I am an idiot (who has actually changed the axle width on an old bike)

 

[midlife]

Just trying to make it easy . I have run extra sprockets on 70's frames BITD and its hard on the thumbs getting the wheel back in lol

Shaun

 

[raleighnut]

Just trying to make it easy . I have run extra sprockets on 70's frames BITD and its hard on the thumbs getting the wheel back in lol

Shaun

Yeah, 120 to 126, just about do-able likewise 126 to 130 but 120 to 130, don't even try.