Roberts (lo pro?) 1993 - how to tell geometry?

[MatBH5]

I was lucky to come across this a few months ago, a fillet blazed Columbus Max Roberts. Dated 1993. Thanks to a very helpful Retrobiker for pick up and post.
It's had replacement forks (I assume) as these are currently a 700c set of straight blade Colnago forks.
I do have a spare pair of Roberts forks (also 1993), at 700c which would need the threaded portion extending to match the short headtube.
However... I can't tell what the fork length should be!
Given the short headtube, I guessed this might be a lo pro frame. It's 52cm c-t seattube, 57cm c-c toptube, I had heard of a 'micro lo pro phase' in the early 90's when a compact design replaced the long seattube and downward sloping / curved top tube of 80's frames.
In absence of Roberts to ask, do these pictures give the assembled experts any clues?
Thanks!

 

[Mike Muz]

Re:

Can't help Matt, but what a lovely project! :xmas-cool:

How short is the steerer in the forks you have? :shock: The top tube looks horizontal. If so, the fork length on those fitted would be right. If not, possibly sloping down, put something under the front wheel until it is horizontal. Then you will know what length forks you will need. Personally, I'd keep it as it is, looks ace with power forks! :xmas-cool:

Definitely a lo pro give those measurements, but you can see that just by looking at it

Look forward to progress mate :xmas-wink:

Mike

 

[MatBH5]

Re: Re:

Can't help Matt, but what a lovely project! :xmas-cool:

How short is the steerer in the forks you have? :shock: The top tube looks horizontal. If so, the fork length on those fitted would be right. If not, possibly sloping down, put something under the front wheel until it is horizontal. Then you will know what length forks you will need. Personally, I'd keep it as it is, looks ace with power forks! :xmas-cool:

Definitely a lo pro give those measurements, but you can see that just by looking at it

Look forward to progress mate :xmas-wink:

Mike

Thanks Mike, so if the top tube is horizontal, then that's likely OK? I wondered about checking the seattube angle somehow..? It's a 700c fork on there now, so I could really only go shorter than this eg 650c, in which case the top tube would slope downwards.
I'd be happy if it was 700c, much easier wheel choice and I've got the perfect Roberts fork already.
To clarify, re. Roberts fork, the steerer is (much) longer than required and when cut down would lose the threaded portion, hence I need the extend the threads.
Marry Xmas, Mat

 

[Mike Muz]

Re:

Twas fashionable in the early '90s to have a horizontal tt, Boardmans Ribble was designed as such. Would be unusual to have a slightly sloping tt.
Angle of seat tube would be around 73-74deg.
As for forks, I'm with you now! I'd just de-sticker the ones on there. Are the others bent, or straight?

Merry Christmas mate!

Mike

 

[MatBH5]

Re:

Ah... so I see that the fashion at the time, as per Boardman, was just to have a compact frame with a very short headtube, in order to get a lo pro position.
The Roberts fork I have is curved, rather than straight. I guess this might not look quite so good.
The straight set on there are genuine Colnago with original painted logos, so I can't de-sticker and it would seem a shame to cut the steerer right down as they'd probably never find a Colnago frame with a 80mm head tube.
A nice problem to have, I guess.
Cheers!

 

[Mike Muz]

Re:

Here we are,

http://farm4.static.flickr.com/3613/337 ... d32693.jpg

I see your predicament regarding the forks. The curved ones look ok on his one.

I think that frame is owned by a forum member now

Mike

 

[Jonny69]

Going on the bottom bracket height, it looks correct with a 700c front wheel and the fork length looks to be about correct. With a 650 front wheel the bottom bracket would be too low. So the top tube should be horizontal on this. I'd say if you extrapolated the frame height so that it had a normal geo, it would probably end up around 56 square, to give you a rough idea of its size.

Measure from the floor to the top tube, front and back. If there's any difference in height it'll tell you how much too long or short the fork is. But it looks about right from the pics.

 

[MatBH5]

Going on the bottom bracket height, it looks correct with a 700c front wheel and the fork length looks to be about correct. With a 650 front wheel the bottom bracket would be too low. So the top tube should be horizontal on this. I'd say if you extrapolated the frame height so that it had a normal geo, it would probably end up around 56 square, to give you a rough idea of its size.

Measure from the floor to the top tube, front and back. If there's any difference in height it'll tell you how much too long or short the fork is. But it looks about right from the pics.

Thanks, I'll give that a go. Appreciate your input. 57cm seems to be about right for me, give or take a cm or two, so I think this'll fit OK.

 

[MartinB123]

Liking the look of this - I have also picked up a smaller sized frame and building it up at the moment - it too has a single chainring like yours, MatBH5.

I guess I have a similar question and sorry to hijack the thread - however, looking for any info on the Cougar i'm building up. It's a 52cm but seems to be pretty comfortable (I usually ride a 56cm) - was this a bog standard frame for the 90's or more suited to a lo pro?

 

[Mike Muz]

Re:

It looks similarly long in the top tube. As mentioned, it would probably suit someone with a seat tube size the same as your top tube.
Again, Boardman rode Cougar lo pros, riding for Kodak IIRC. as well as Gan, initially.