Audax/'Randonnée' bike - conversion candidate?

[zigzag]

you can measure geometry with tape measure and protractor, or by taking picture from a side an measuring on paper as ergle suggested. if bike was designed to be used with "shopper" bars and it fits you as it is, then it's not likely it will fit with drop bars even with a shorter stem. the difference in reach (if you are on hoods) can be ~20cm which is huge. online calculators (competitivecyclist etc.) give sizes that are too big for me, but they could work for you.
the only sizes i am interested are top tube (virtual horizontal c-to-c), head tube and seat tube (c-to-t). seat tube and head tube angles?.. i don't know and i don't care, something between 72'-74' i believe. i would use the methods above to measure them.

 

[velovoice]

You are approaching this project 'arse about face'. Firstly, measure YOU. Do the sums to find your perfect frame; and then move the seat and handlebars around ( or put the measure tape on the bike and assess what stem you need ).
Reach is from the theorectical seat clamp centre to the centre of the handlebars where they join the stem.
Seat angle doesn't matter a jot. The critical measurement is the horizontal distance from the pedal spindle to your hip ball joint centre. Head angle shouln't be an issue. Puch have been making bikes for many years.

Jimboalee - I do not dispute what you say, but I'm afraid it is you who's missing the point of what I've been asking here. Maybe if I've misled you by referring to my experiences with this bike, which has prompted all this discussion about fit. If so, I'm sorry. I love this bike and I love to talk about it, so I succumbed to a "show and tell" temptation. But I DO NOT have any questions about how the bike fits me, either as it is set up now (for upright riding) or what to do to about fit when/if I swap things out to set up for touring.

I guess in retrospect I should have asked a purely objective question without any reference to me and how I ride now or want to ride in future, namely: how does one measure a bike's geometry?

I think Ergle has given me what I need. It won't be exact but I wasn't looking for a formula, just a method.

So cheers for that. I'll go off and do what he's suggested and post again (or PM him) if I'm confused about how to do it.









P.S. Just in case it's still not 100% clear: THE BIKE FITS.

 

[jimboalee]

Jimboalee - I do not dispute what you say, but I'm afraid it is you who's missing the point of what I've been asking here. Maybe if I've misled you by referring to my experiences with this bike, which has prompted all this discussion about fit. If so, I'm sorry. I love this bike and I love to talk about it, so I succumbed to a "show and tell" temptation. But I DO NOT have any questions about how the bike fits me, either as it is set up now (for upright riding) or what to do to about fit when/if I swap things out to set up for touring.

I guess in retrospect I should have asked a purely objective question without any reference to me and how I ride now or want to ride in future, namely: how does one measure a bike's geometry?

I think Ergle has given me what I need. It won't be exact but I wasn't looking for a formula, just a method.

So cheers for that. I'll go off and do what he's suggested and post again (or PM him) if I'm confused about how to do it.









P.S. Just in case it's still not 100% clear: THE BIKE FITS.

Sorry about that.

Maybe the answer to your question is burried too crypticly within my replies.

In short, you don't have to measure the geometry of a frame. As long as the 'stand over height' is OK for you, the bike manufacturers will have got all the angles and lengths right to suit depending on the purpose the bike is to be used for.

 

[MacB]

Ah, I get it Rebecca, and I also have a Surly Cross Check, great bike. So you'd like a frame geometry chart, 2 options, find a bike shop than can measure it up for you. Alternatively, do the measurements yourself, a tape measure should be enough, no need for a protractor. Just measure the length of each tube and and dig out your schoolday geometry re angles in triangles/parallelograms, etc.

I'd download an exisiting geometry chart and bung it into a spreadsheet, diagram and table. you can then creat your own table in which you record the actual measurements you take, headt tube, top tube, seat tube, chain stays, etc. A little bit of nifty formula work and this can be made to calculate the unknowns like angles and virtual top tube.

Think of it as a homework assignment....plus I now hate you!!!!!!!! coz I know I'm going to try and do this myself, sad git that I am I find it irresistable. If it pans out I'll bung you a copy of the spreadsheet. I'll work around known geometry and see if I can get a formula driven table to come up with the same results as the manufacturers table.

 

[MacB]

you can measure geometry with tape measure and protractor, or by taking picture from a side an measuring on paper as ergle suggested. if bike was designed to be used with "shopper" bars and it fits you as it is, then it's not likely it will fit with drop bars even with a shorter stem. the difference in reach (if you are on hoods) can be ~20cm which is huge. online calculators (competitivecyclist etc.) give sizes that are too big for me, but they could work for you.
the only sizes i am interested are top tube (virtual horizontal c-to-c), head tube and seat tube (c-to-t). seat tube and head tube angles?.. i don't know and i don't care, something between 72'-74' i believe. i would use the methods above to measure them.

I'm not sure how you could get a 20cm reach difference, or maybe that sort of problem with No's, and measuring skills, is why you don't get good results from the Competitive cyclist fit formula

 

[velovoice]

if bike was designed to be used with "shopper" bars and it fits you as it is, then it's not likely it will fit with drop bars even with a shorter stem. the difference in reach (if you are on hoods) can be ~20cm which is huge.
....
the only sizes i am interested are top tube (virtual horizontal c-to-c), head tube and seat tube (c-to-t). seat tube and head tube angles?.. i don't know and i don't care, something between 72'-74' i believe. i would use the methods above to measure them.

Thanks Zigzag, I agree that sounds sensible.

The bike came out of the Puch factory with drop bars but somebody at some point later put MTB bars on it, which is what it had when I bought it in May. They were truly awful: all wrong for handling and (at the risk of making a reference to FIT! ) really uncomfortable for me (wrist pain). The angle of the current North Road (purchased directly from Pashley - it's what they put on their Guv'nor, upside down) cured the wrist problem and has been really comfortable for upright riding. The quill stem is original.

But looking ahead to my longer-distance road riding aspirations... it's back to drop bars.

 

[MacB]

Just to add, the other bit of info you're looking for will need some googling, as in what sort of handling/ride you can expect from a given geometry, fork trail and ride position. Opinion does seem to vary on this, maybe a good start would be Sheldon Brown and the CTC collated info via Chris Juden.

 

[velovoice]

Just to add, the other bit of info you're looking for will need some googling, as in what sort of handling/ride you can expect from a given geometry, fork trail and ride position. Opinion does seem to vary on this, maybe a good start would be Sheldon Brown and the CTC collated info via Chris Juden.

thanks for the reminders. It's been a while since I've read Sheldon views on this and somewhere I've bookmarked Chris Juden's but hadn't read it yet...

"Homework"! I do love researching stuff like this... Will definitely be interested in seeing anything you come up with in the way of spreadsheets etc - thanks!

 

[jimboalee]

I'll relay a little story about when I spent £1000 on a Specialized SWorks.

I went into Mike Vaughan Cycles in Kenilworth wearing running shorts, because I know there is a freckle on my thigh that is at the height of the top of the headset of any bike which is the correct frame size for me.

The chappie showed me a couple of Treks, a Giant and then the Spesh. I measured them by standing next to them with the leg of my shorts lifted to reveal the freckle.

Trek, Giant and Specialized are no mugs so I knew that if this measurement was right, adjusting the bike for me would be no problem.

I got the bike home, tweaked it and rode from Wolverhampton Station to The Poderosa Cafe at the top of Horseshoe Pass, and back.

I wasn't particularly worried about tube angles. I know my own body measurements, the calculations and have a list of the critical dimensions to adjust a bike to to fit me.

 

[velovoice]

Sorry about that.

Maybe the answer to your question is burried too crypticly within my replies.

In short, you don't have to measure the geometry of a frame. As long as the 'stand over height' is OK for you, the bike manufacturers will have got all the angles and lengths right to suit depending on the purpose the bike is to be used for.

No probs. And yeah, what I'm after is what those angles and lengths ARE. So far I've been taking on faith everything I've read about the Puch models from the 1970s. There's precious little about their mixtes but what there is tends to suggest their approach was in line with the French and German mixte framebuilders i.e. a unisex lightweight steel road bike commonly used by cyclotourists (but not racing folk). I just want the satisfaction of seeing the mathematical proof of that!

 

[RecordAceFromNew]

I think the bike looks like a really good basis as an audax bike - in terms of geometry the fork rake and seat tube angle etc. indicate it is perfect (compared to most modern road bikes) for long distance. While they are heavy compared to modern counterparts, the Brooks/Carradice and matching leather handlebar tape also look fabulous!




Looking at the photos of the bike, I might be mistaken but my only observation is that if the rims are chromed steel they might not provide brilliant stopping power with the Weinmann single pivot caliper brakes, especially in the wet. For a simple solution it is possible that Kool Stop salmon brake pads might help. Modern double pivot caliper brakes on alloy rims are more effective, but change will probably involve getting 700c wheels and long drop brakes (if the rims are 27" at present) and spreading the frame's rear dropouts to accommodate the longer axles of modern hubs. New 27" alloy rims/wheels/tyres do exist, but the best rims/hubs/tyres are unfortunately harder to source in 27" today.

A couple of options exist for improving the range of gearing for hills. Depending on what is there already, potentially the easiest is to get a set of cogs with wider range at the back (such freewheel might be difficult to source for the existing wheel, but wide range cassettes are readily available for new 700c wheels) - no change is then necessary to the current stem mounted shifter in friction mode. A more involved option is to install a new front derailleur combined with new double or triple chainset and suitable shifters (probably indexed sti shifters/brifters), a new chain and rear mech with longer cage might also be required in this case. <br style=""> <br style="">

On the other hand, this frame is also eminently suitable for conversion into a single speed/fixie if the CC turns out to be a better long distance runner...

 

[velovoice]

I'll relay a little story about when I spent £1000 on a Specialized SWorks.

I went into Mike Vaughan Cycles in Kenilworth wearing running shorts, because I know there is a freckle on my thigh that is at the height of the top of the headset of any bike which is the correct frame size for me.

The chappie showed me a couple of Treks, a Giant and then the Spesh. I measured them by standing next to them with the leg of my shorts lifted to reveal the freckle.

Trek, Giant and Specialized are no mugs so I knew that if this measurement was right, adjusting the bike for me would be no problem.

I got the bike home, tweaked it and rode from Wolverhampton Station to The Poderosa Cafe at the top of Horseshoe Pass, and back.

I wasn't particularly worried about tube angles. I know my own body measurements, the calculations and have a list of the critical dimensions to adjust a bike to to fit me.

Excellent!!

The day I settled on my Cross Check, I test rode it in a 46cm and a Specialised Dolce in a 48cm. The Spesh's fit was Perfect - so perfect I was sorely tempted to buy it right then and there. But I knew I wanted steel. The CC doesn't come in a 48cm. The reach on the 46cm felt short. The shop tried to talk me into the 46cm but based on how it felt and what I already knew of the size/geometry chart on Surly's website, I figured I wanted a 50cm. The shop didn't have that. Turns out, nobody in London did. So that's how I come to be waiting -- as patiently as possible! -- for a special order 50cm bike from the USA. It should be the right size, in a basic blank canvas kind of way. Then the fun of tweaking the fit (based on what I know about my own measurements and how my other bikes fit) can begin!

 

[velovoice]

I think the bike looks like a really good basis as an audax bike - in terms of geometry the fork rake and seat tube angle etc. indicate it is perfect (compared to most modern road bikes) for long distance. While they are heavy compared to modern counterparts, the Brooks/Carradice and matching leather handlebar tape also look fabulous!

Thanks!
Yes, my impression is that the quite pronounced fork angle, rake and trail are good indicators for distance. Had a comment from a fellow FNRttC'er just the other night on how unusual this looks to 'modern' eyes.

Looking at the photos of the bike, I might be mistaken but my only observation is that if the rims are chromed steel they might not provide brilliant stopping power with the Weinmann single pivot caliper brakes, especially in the wet. For a simple solution it is possible that Kool Stop salmon brake pads might help. Modern double pivot caliper brakes on alloy rims are more effective, but change will probably involve getting 700c wheels and long drop brakes (if the rims are 27" at present) and spreading the frame's rear dropouts to accommodate the longer axles of modern hubs. New 27" alloy rims/wheels/tyres do exist, but the best rims/hubs/tyres are unfortunately harder to source in 27" today.

Fortunately, the rims are alloy not steel. But braking power is not great - esp in the wet!
Will definitely be switching to Koolstops for the next pads. I think whole new wheelset is probabably in order too. Thanks for the info on sizing. I've been aware that options are limited for 27" tyres but hadn't got as far as scoping out available rims in that size and suitable hubs etc. More to think about, subject to groupset decision....

A couple of options exist for improving the range of gearing for hills. Depending on what is there already, potentially the easiest is to get a set of cogs with wider range at the back (such freewheel might be difficult to source for the existing wheel, but wide range cassettes are readily available for new 700c wheels) - no change is then necessary to the current stem mounted shifter in friction mode. A more involved option is to install a new front derailleur combined with new double or triple chainset and suitable shifters (probably indexed sti shifters/brifters), a new chain and rear mech with longer cage might also be required in this case. <br style=""> <br style="">

On the other hand, this frame is also eminently suitable for conversion into a single speed/fixie if the CC turns out to be a better long distance runner...

Yup, those are exactly the options I'm mulling over.

Part of me wants to retain whatever's original that is (1) in good condition, (2) still working well, and (3) fit for purpose.

A fellow club member suggested simply adding a second front cog (+ FD) but he's not familiar with vintage components and hasn't looked at the Puch carefully so I'm not yet sure if that's a viable option.

That desire for originality notwithstanding.... it's really tempting to go for a whole new triple as you say, for maximum range of performance which could well put even the LEL within reach for this bike (??!!!!) That would be a pretty major operation, not cheap either and of course would utterly change the character of the bike, leaving essentially just the frame (and possibly headset and/or bottom bracket) as original.

These are all questions I think for the LBS - if I can get hold of one particular guy there who does know something about vintage road bikes (his colleagues are all willing to help but really don't have a clue!)

 

[zigzag]

I'm not sure how you could get a 20cm reach difference, or maybe that sort of problem with No's, and measuring skills, is why you don't get good results from the Competitive cyclist fit formula

quite simple, if northroad bar contact points are 10cm towards you from the centre of handlebar clamp, and drop bar hoods are 10cm away from the centre, that's 20cm difference, i'm sure you can understand that

 

[MacB]

quite simple, if northroad bar contact points are 10cm towards you from the centre of handlebar clamp, and drop bar hoods are 10cm away from the centre, that's 20cm difference, i'm sure you can understand that

call me stupid, no go on, I wasn't comparing with Northroads, in fact I'd assumed that was part of the 'too upright' probems Rebecca had because, having tried them, it's very hard to get a long enough stem to accomodate a decent riding position. unlwess of course you move everything else back as well, but I found I didn't like moving my saddle to far back from the BB....so, sorry my man, my error there