Building gravel bike from retro road frame

[Kaufman]

Hi

I have a 1980’s Pug frame in my garage. It’s in decent Knick and I thought that I would have a crack at building it into a half decent gravel bike using modern parts.
Can anyone think of a reason I can’t do this?
I have read that I have to put square taper bb on it. Anyone know of decent gravel suitable crankset that fits square taper?
Will a standard sealed Shimano bb do the job?
It has the headset on it but thought I would change for a more modern one as better sealed??
As stated, anyone think of any pit falls? I need to meticulously plan beforehand as don’t want to get half way through and realise it has gone t*ts up.
Thanks

 

[Captain Stupido]

Re:

Depends how you define "gravel bike"... from where I stand the key difference between a "gravel" bike vs a conventional (retro) road bike is chunkier tyres and disc brakes. A 1x drivetrain is also common, but perhaps not a defining feature.

You might be able to squeeze chunky tyres in your frame, depends...but you won't be able to make it run disc brakes without a fight...

...modern(ish) 1x drivetrain - sure, if it appeals - I'd probably go for a retro square taper chainset with a cheap chinese narrow-wide chainring. 9 speed might be enough for you - and it's probably a relatively cheap and easy option.

 

[pigman]

Re:

With it being an older Pug, you may need french threaded bottom bracket and headset. Worth checking as they aren't as common.

Not having disc brakes wouldn't worry me, just put some modern dual pivot calipers on. Modern ones from the likes of Acor and Alongha do work quite well. But you're probably looking at 37mm tyres plus adequate clearance for mud, sticks etc, so check you have this.

To reassure you forget the modern term "gravel bike" and substitute with "rough stuff bike" or "touring bike without mudguards" and you effectively have the same thing

 

[jimo746]

I have a 1980’s Pug frame in my garage. It’s in decent Knick and I thought that I would have a crack at building it into a half decent gravel bike using modern parts.

...anyone think of any pit falls?

Tyres, how wide a tyre can you fit in the frame/fork? Ideally you want cx width of 33c or so at least. Off-roading on skinnier tyres can be done, but its not much fun, and punctures aplenty unless you run 100psi!!

Wheels, 80's bike may be 126mm rear spacing, you could cold set the frame to 130mm though if its steel, otherwise modern wheels could be a problem.

Bars and stem, most modern bars will be 31.8mm clamp, and Ahead style fitting, you might need a 1" quill to 1"1/8 Ahead adapter.

Brakes, caliper brakes off road give little power in the slop , and even less mud clearance ,

You might be better off keeping it mostly original and just seeing what size tyres it'll take first, before jumping in the deep end... or considering a different frame choice (a Touring frame could work).

 

[legrandefromage]

Most peugeots were standard threading from the late 1970's onwards.

But as already mentioned, you will find it hard to fit the larger tyres that 'gravel' bikes use. So as also mentioned, you'd be better of finding something else, especially something with cantilever brakes

Heres something I built in 2012 before I'd even heard of (bleurgh) gravel bikes, it was just an old sporty tourer from 1974 with a bit of off-road capability

Tyres were Schwalbe Land Cruisers

 

[Kaufman]

Re:

Thanks everyone

 

[M_Chavez]

Re:

"Anyone know of decent gravel suitable crankset that fits square taper"

Stronglisght are great (Spa cycles). I've got three triples on my & mrs' bikes with different gearing.

I think 42c is the "gravel" tyre, but I can only just about fit 37c + mudguards on my cx frame, and they seem to be holding up well.

Have fun!

 

[glpinxit]

I’m not clear why square taper is necessary. You should have no problem fitting more recent BB if you want- I recently ran Shimano Hollowtech cranks with 26mm spindle in a late 1970s BSA bottom bracket frame with modern Shimano BSA threaded BB external bearing BB cups.
Similarly 126 mm rear spacing isn’t so different that you need to change it to run 130 mm OLN rear wheels.
Main issue will be brakes. Ideally your frame needs bosses so you can run cantilever or V brakes. Even with longer drop calliper brakes mud built-up may jam a wheel and if it is a short-drop frame then you will be limited to skinnier tyres too.

 

[pigman]

Re:

Just for my education, what is the purpose of a gravel bike? As its name suggests, I wouldn't have thought it was for deep mud plugging. For that there is the mtb. I would have thought it was for nature trails, canal paths, cinder track .... more hard packed surface than mud.

 

[Kaufman]

Re:

Hi
Yes, exactly those terrains. No intention of proper off roading