Decoding geometry: will this bike be a nervous nelly?

[Robbos]

For my latest project, I'm about to build up a 1993 Ryffranck. Very nice SLX frame, with great attention to detail. I talked to M. Ryffranck a few months ago (still full p&v at 91 years old!). He kindly sent me the geo sheet. I'll build the bike either way, but I am nervous of the 74 degree head angle. I'm personally not a fan of crit geometry and just overly nervous bikes in general. Other than the head tube angle, anyone have any opinions about other details like fork offset, that may contribute to or reign in the frame's nervousness?

[EricEstlund]

The steep head angle is appropriately balanced with a short fork offset. BB drop is also reasonable, as is chain stay length. So it will be a bit "quicker" feeling than some, but not what I would call nervous if you have ridden and enjoy other bikes of the era.

[Robbos]

The steep head angle is appropriately balanced with a short fork offset. BB drop is also reasonable, as is chain stay length. So it will be a bit "quicker" feeling than some, but not what I would call nervous if you have ridden and enjoy other bikes of the era.

Thanks Eric. I've ridden a different array of older lugged road bikes, some more lively or nervous than others. But one of the last was a Marinoni build Argon 18 which was ultra nervous and seemed to require constant attention at the bars. So hopefully this one won't be as bad.

[FlashUNC]

Got a 74 degree head angle on my Della Santa. Stable as a rock.

As Eric notes, it ain't just about the head angle.

[moobikes]

A longer stem helps a little bit to tame the front end.

The drawing is just as beautiful as the bike.

[ultraman6970]

74 degrees in the front back in the day was normal, dunno what the op is talking about :P

The bicycle will be ok, if you fit it wrong it will handle wrong tho. Actually you might find it more comfortable....

[PacNW2Ford]

mid-sized 90's Paramounts and Waterford's were 74°/40mm rake. I rode them for a couple decades, so that was my "normal".

[fiamme red]

This Man Built 600 Steel Bicycles In His Shed - Meet J.P. Ryffranck: https://www.youtube.com/watch?v=f7-8cI17Lgg.

[Kontact]

...

[tv_vt]

Maybe I'm not seeing it, but without the fork rake, you can't really tell what the trail will be or how quick the steering will be.

The BB height is a bit on the high side compared to what is typical nowadays. I get a drop of 68mm for that frame, which could also make it feel a bit unstable, compared to a 70-75mm drop, which would get you more 'in' the frame instead of on top of it. But that's splitting hairs.

[.RJ]

The rake is in the chart - 1-5/8" or ~41mm.

Is anyone else maddened by the drawing shifting back and forth between metric and imperial measurements?

[William]

This Man Built 600 Steel Bicycles In His Shed - Meet J.P. Ryffranck: https://www.youtube.com/watch?v=f7-8cI17Lgg.

Yup, scroll down to the "J"'s... :)

https://forums.thepaceline.net/showthread.php?t=115890


Nice ride!:cool:





William

[FlashUNC]

The rake is in the chart - 1-5/8" or ~41mm.

Is anyone else maddened by the drawing shifting back and forth between metric and imperial measurements?

That struck me as odd.

[EricEstlund]

The metric system wasn't adopted officially in the UK until 65'. It was very common to see bikes there (and here) in imperial measurements. Switching and mixing units on the drawing is probably shorthand to what he was doing in the shop.

[colker]

maybe i'm not seeing it, but without the fork rake, you can't really tell what the trail will be or how quick the steering will be.


1 5/8.

[tv_vt]

1 5/8.

OK, so 41mm rake would get you 55mm of trail. A bit on the nervous side. Seems the 'normal' is about 58mm. Personally I find myself liking trail in the low 60's for a road bike.

[Robbos]

This Man Built 600 Steel Bicycles In His Shed - Meet J.P. Ryffranck: https://www.youtube.com/watch?v=f7-8cI17Lgg.

Yup, that's JP. He still swears by silver brazing. Marinoni and he are friends but disagree, Marinoni swears by brass. But most Ryffrancks, including this one, were painted at Marinoni.
Here are a few gratuitous shots of the beast.

[OtayBW]

OK, so 41mm rake would get you 55mm of trail. A bit on the nervous side. Seems the 'normal' is about 58mm. Personally I find myself liking trail in the low 60's for a road bike.55 mm nervous? Perhaps, but only at speed. I always thought of 56 mm as being kind of neutral, but that's just my sense of it. My favorite handling bike is actually close to 65 mm.

[colker]

OK, so 41mm rake would get you 55mm of trail. A bit on the nervous side. Seems the 'normal' is about 58mm. Personally I find myself liking trail in the low 60's for a road bike.

Is there a more imprecise word than "normal"?
Every road bike i owned had a 73.5 head angle and none felt nervous. 74 is not that far.

[Mark McM]

55 mm nervous? Perhaps, but only at speed. I always thought of 56 mm as being kind of neutral, but that's just my sense of it. My favorite handling bike is actually close to 65 mm.

Nervous at what speed? My Ritchey Road logic (with a trail of 51 mm) isn't at all nervous at speed - although I have to admit I haven't exceeded 55 mph. My Redline Conquest cyclocross bike has a trail of 63 mm, and I find its handling to be slow and ponderous on pavement.

[OtayBW]

Nervous at what speed? My Ritchey Road logic (with a trail of 51 mm) isn't at all nervous at speed - although I have to admit I haven't exceeded 55 mph. My Redline Conquest cyclocross bike has a trail of 63 mm, and I find its handling to be slow and ponderous on pavement.My point is that 55 mm trail is really NOT 'nervous' handling. That said, it's all personal observation or preference. My high trail bike is perhaps my best handling bike, but that's at high speed. YMMV...

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[Peter P.]

I ride a similar sized bike.

Bikes that size usually don't have head angles that steep. 73 degrees is typically the max.

I personally wouldn't like such a steep head angle/fork rake combo.

Please report back with your experience after you build it up.

[Robbos]

For those interested, finished building this up and put it to a first text. In Custom Bike section.