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PostPosted: Wed Aug 09, 2017 6:24 pm 
gold | rider | rBoTM
gold | rider | rBoTM

Joined: Sat Jan 05, 2013 5:06 pm
Posts: 12296
Location: Worthing, West Sussex
Hi folks,

I've been looking at a few older road bikes lately, from late '70s. I may even be tempted into buying a frame/set if I see something I like, 57-59cm, although it's a bit before my cycling era. Preferably a Bianchi, but see what turns up.

So I was wondering, when did wheel size change from 27x1 1/4 to 700c? I don't want to end up with something that is no good for the calipers and wheels.

I have an tricolour Ultegra groupset looking for a home, but brakes suit 700c wheels that I already have too. Just need the frame to go with it.

Thanks,

Mike


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PostPosted: Wed Aug 09, 2017 6:53 pm 
King of the Skip Monkeys
King of the Skip Monkeys
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Joined: Wed Nov 07, 2007 4:34 pm
Posts: 27656
Location: Moomin Valley
Hard to say, I have 1950's 700c wheels but many of my English frames were designed for 27 1/4 that are much younger.

I am currently riding a 1979 700c MKM with full modern 10 spd uletegra /105.

At a guess, I'd say 700c was used abroad for decades whilst the brits were charging around on 27. I also guess racing brought 700c over and manufacturers quickly followed suit?


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PostPosted: Wed Aug 09, 2017 6:56 pm 
retrobike rider / Gold Trader
retrobike rider / Gold Trader

Joined: Sat Jul 21, 2007 9:48 am
Posts: 7423
Location: Bristol
Tubs were always 700c sized, so posh race stuff is likely to be 700c much earlier than lesser stuff or tourers etc


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 Post subject: Re:
PostPosted: Wed Aug 09, 2017 7:00 pm 
Retro Guru

Joined: Thu Sep 01, 2011 5:11 pm
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Location: Left Coast of Canada
I didn't become aware of 700C as a standard for road bikes until the mid 80's in Canada, but I wasn't racing or riding fancy European bikes. I road either domestic bikes like Sekine or Raleigh's and being a Commonwealth country we were following Imperial standards until the 70's. The 27 inch wheel seemed to be more common on lower end bikes and sport/touring bikes in the early 80's. That being said I have what is likely a 79 or 80 Apollo (Kuwahara) with 700C wheels stock and the 1981 Trek 515 I got for MrsT came with 700C wheels as well.


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PostPosted: Thu Aug 10, 2017 10:24 pm 
rider | rBoTM Winner
rider | rBoTM Winner
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Joined: Fri Jan 25, 2008 1:42 pm
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Location: West Yorkshire
I remember 700c's coming in around 1977, a clubmate had a pair with (I think!) Michelin Elan tyres. A revelation as, being the same size as tubular wheels, there was no need to fiddle around moving brake blocks etc. if you rode out to a race on 27" wheels. It also meant that there was an alternative to riding tubulars on a daily basis for training or commuting.


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 Post subject: Re:
PostPosted: Fri Aug 11, 2017 9:34 am 
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Joined: Mon Sep 24, 2012 9:10 pm
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Being a Brit, I'm not quite sure of my facts here either, but like LGF I suspect that 700c was the continental standard for both sprints and clinchers from way back, so if you are looking at continental frames like Bianchis there should be no conflict.

It is probably just the British frames which might have issues in this area. But as cce says, anything of quality from the '70s that is self-evidently a dedicated race frame- close clearances, short chainstays, an inch or so of fork rake- is going to have been built for sprints anyway. Incidentally, what was called 'close clearance' in the '70s was a brake drop of 45-50mm. I would guess that tricolor calipers are 39-49mm, so even with a 'close clearance' frame, you might be right at the bottom of the slots, as I was with Shimano 600 sidepulls on a '75 frame.

Yeah, I think the Mavic Module E/Michelin Elan was introduced in '75. Those were the first faux sprints/tubs - i.e. high pressure 25mm tyres on 20mm rims. They didn't become mainstream until the '80s. Before those, both in Britland and on the continent, clinchers were fat- 27x1 1/4 was the British size for 'racers' i.e. bikes with drop handlebars from Halfords and the like..


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 Post subject: Re:
PostPosted: Sun Aug 13, 2017 2:00 pm 
Old School Hero

Joined: Sat Oct 10, 2009 12:31 pm
Posts: 177
Many vintage frames have different drops f&r. My Holdsworth (with its original fork) is 51mm front but a huge 67mm rear. Would have been 47mm/63mm with 27" wheels.


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 Post subject: Re:
PostPosted: Sun Aug 13, 2017 2:41 pm 
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Joined: Sun May 05, 2013 12:12 pm
Posts: 1608
Location: Bournemouth
Interesting stuff.
Is there a rule of thumb measurement you can make on a bare frame/fork to understand which you have?
Say drop out to brake fitting?
Or is it a case of putting in a wheel, offering up a brake etc?
Thanks
Mat


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 Post subject: Re:
PostPosted: Mon Aug 14, 2017 7:50 am 
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Joined: Mon Sep 24, 2012 9:10 pm
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I guess the only meaningful measurement you could take on a bare frame would be from a point on the central axis of the (imaginary) axle midway between the dropouts to the central axis of the brake pivot. It'd be difficult to be accurate with just a ruler. Fwiw, on a frame designed for sprints, short-drop brakes, and close (not ultra-close) clearances I'd expect that measurement to be something pretty close to fourteen inches.


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PostPosted: Mon Aug 14, 2017 8:13 am 
retrobike rider / Gold Trader
retrobike rider / Gold Trader

Joined: Sat Jul 21, 2007 9:48 am
Posts: 7423
Location: Bristol
the diameter difference between a 700c and a 27in wheel is only 8mm, so the difference in fork length would only *need* to be about 4mm, which is loads in the context of brake drop, but hardly anything in the overall length of a fork (~370mm for a modern short-drop race fork)


Last edited by cce on Mon Aug 14, 2017 8:14 am, edited 1 time in total.

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