Framebuilders - Randonneur Geometry

Does anybody have experience with the short trail geometries (3.5-4.5 cm) used by the Alex Singer and Rene Herse randonneur bikes that run with front bags and wide tires? The reason I ask is that there seem to be a lot of suitable bike frames available with more conventional trail from 5-6 cm and I am not sure that paying extra just to get the decreased trail would be worth it.

I think the point would be whether these other bikes just have rondonneuring paintjobs, or where really designed from the ground up for the purpose. If they were, then you have a difference of opinion on what kind of bike it is. Something like the PBP run out in the front of the pack might require more lively handling than some guy churning away in his own bubble. With custom frames every single detail needs to be worked towards the overall service use of the bike.

The shorter trail should give more stable stearing. Average trail is perfectly useable, slow handling when you need fast is less tolerable. So the normal trail is more versatile, you need to know the stable handling is your performance goal.

the decreased (before edit was -increased- ) trail mostly lets you get away with a loaded front bag. The obvious solution is a seat bag. I'll report back after my first 400k.

That's a reasonable way to look at it, though there are lots of bikes with front bags and standard numbers. I prefer less trail because the bike is less twitchy, I can ride the paint line with less thought. :)

my bike has fairly relaxed racing geometry. It's pretty typical of the bikes I see on Brevets. If I put a few pounds in my handlebar bag, all of a sudden it becomes much more difficult to ride no-hands.

I definitely plan on building a rando geometry bike.

Sorry, my dyslexia got the best of me again. Rando bikes have less trail/more rake.

All the frames I have built for myself are exact copies of French randonneuring frames from the 40s and 50s. I have used them with 700c/30mm tires, and my current bike uses 650b/42mm tires. I have found that these bicycles do indeed handle better with a loaded handlebar bag than without. Without, they can be slightly unstable, especially at higher speeds. This is not a severe problem; a small shimmy at 25-30 MPH while riding no hands, for example.

Unfortunately, I have never ridden a high trail bike with a handlebar bag, so have nothing with which to compare.

When it comes right down to it, "randonneuring geometry" is nothing more than larger-than-normal fork rake used with the typical 72-74 degree head angle. The simplest way to get there from here can often be just paying your local builder $100 or so to re-rake your existing fork. That may well damage the paint, and it will also decrease tire clearance somewhat, but has been done with success. It's also entirely possible to have a new fork made for considerably less than the cost of a new frame.

HTH!

"much more difficult to ride no-hands". That I can believe. The last commercial touring bike I owned would not ride no-hands regardless of front load. Kinda scarry.

I keep meaning to mention that there is an e-book: A Rider's Guide to Building the Long Distance Bicycle. Don't know anything about it myself, but it sounds interesting.

http://www.roadbikerider.com/ldb_page.htm

I was looking for something in the basement today and found all my framebuilding stuff -- finally! I have a pile of the old style Reynolds 531 narrow fork blades. My new project is to build a rando fork. Maybe I'll build one of those mini racks to go on it. Trying to decide what brazeons to put on there. I also have to decide if I should put Mafac cantis, or new style cantis on it.

I have a couple of sets of those blades myself. I haven't used any of them yet as I have never been able to find a fork crown wide enough to accommodate 42 mm tires with fenders. I am planning on building a British style single-speed touring bike copied from a 1930's frame and will be using 26 or 28 mm tires, so a crown I have should work.

What are the differences in the cantilever studs for Mafac cantis and those for "new style" cantis?

What are the differences in the cantilever studs for Mafac cantis and those for "new style" cantis? I'm pretty sure the holes for the springs are 180 degrees off. Which would be a little too much spring tension.

Huh. I've never heard of that. I have used old Mafacs, along with current cantilevers from Tektro and Shimano, and V-brakes as well, and they've all used the same studs. I have heard that the Pauls are very sensitive to stud positioning, but they still have the spring holes on the inside of the stays/blades.

Do you have any pictures?

From the Paterek Manual:

"The comfort range of trail is 5.0 to 6.5 centimeters. . . A bike with less trail will be more 'twitchy' or nervous. A bike with more trail will be more 'relaxed.'"

I've always interpreted this and other explanations/analysis of trail to mean that bikes on the lower end of the trail spectrum will turn faster and feel more responsive, but not be as stable or track as straight as bikes at the upper end of the spectrum. Thus, a racing or track bike would have less trail, while a touring or randonneuring bike would have more. It also seems that trail is mostly achieved with headtube angle, while fork rakes remain in the 4.0 to 4.5 cm range (especially when using carbon forks which come in limited rakes). Again, racing bikes have steeper HT, while touring bikes have a shallower HT.

But this thread now has me very confused. I've also noticed that some modern track bikes have as little as 2.5 cm of fork rake and trail measurements above 6 cm.

But my Surly Long Haul Trucker -- which is super stable with a heavy load -- has a trail of 6.3 to 6.5 cm depending on tire size.

Can someone help clear up my confusion?

Huh. I've never heard of that. I have used old Mafacs, along with current cantilevers from Tektro and Shimano, and V-brakes as well, and they've all used the same studs.
I take it all back. I just went and looked at my mafac installation of old, and they are the same as the newer ones.
I know the brakes fit on the newer studs, I started to install some Mafac cantis on a cheap trek before I realized half
of the studs were broken.


As far as Paternak and trail goes, it isn't that easy. I don't think that trail tells the whole story. Head tube angle, and rise/fall have something to do with stability. Clearly a more relaxed head tube angle and longer rake will be a more relaxed ride. This would mean less trail.

Trail is made up of head tube angle, wheel radius and fork offset (aka "rake), so by talking about trail we cover a range of variables. If you increase head tube angle without changing radius or offset, you get more trail (more stable, less twitchy). If you increase rake without changing the other two, you get less trail (less stable, more twitchy, faster response to 'bars). If you put on a smaller wheel (less radius) without changing head angle or offset, trail will decrease. But doing anything that will raise or lower the front relative to the back changes head angle a bit, so it affects how much trail change you'll get.

I think Paterek has it right.

Another source of confusion is that in motorcycle literature the terms are used in different ways than cyclists do.

Road Fan

Question:

How do low-trail rando bikes handle no-handed, with a front load and the wider tires? I've been thinking of a brevet bike, too, but I want to be able to no-hand. I generally believe that if the frame and wheels are aligned and the headset is good and adjusted right, it can be no-handed.

Road Fan

Paterek et al. oversimplify trail quite a bit, IMO. I agree with the Paterek POV when we are talking about narrow high pressure tires with no load. Beyond that it gets more confusing. There is little agreement, as can even be seen right here on this thread.

In my experience...

Standard trail (+/- 6 cm) works just fine with 20-25 mm tires and no load. Especially at higher speeds (20 MPH+) it makes for a comfortable and stable bike. At lower speeds, like below 10 MPH, you will start to notice the wheel flop caused by excess trail. The "standard" test is to slowly roll down a hill with no hands. At first you cannot do it, because the front wheel will flop to one side or another. As speed increases, steering stabilizes. In my experience the typical standard trail bike will stabilize somewhere between 8-12 MPH.

Now, putting a bag on the handlebars of this bike sends things straight to hell, as weight on the front wheel really brings out the tendency for the wheel to flop. A handlebar bag combined with 6 cm of trail may mean the bike doesn't stabilize until 15 MPH or higher -- at least according to what I have read. This, I think, is why handlebar bags have such a poisonous reputation in some circles.

At the same time, wide tires work fine with standard trail at moderate speeds, but as speed increases, wide tires tend to emphasize the stability provided by higher trail. This can get to the point that you feel like you are "plowing a furrow" with the bike, as it really starts to resist rider inputs.

Now, I think the key with low trail is that you are minimizing wheel flop. This is important with the handlebar bag, again bearing in mind that the bag really emphasizes flop -- which, BTW, is amply illustrated by simply rolling your handlebar bag equipped bike around the garage: watch out for top tube dents! So the goal of minimum trail is to restore the "neutral" handling of the 6 cm trail bike which was lost by the addition of the bag. The downside is that, as speed increases, inadequate stability can become an issue with a low trail bike, especially if you ride the bike without the bag. Frame alighnment is supposedly more critical with a low trail bike than with a higher one. This too is where the fat tires come into play, as they tend to have a stabilizing effect upon the whole affair while not significantly affecting wheel flop.

So essentially, we are using low trail to negate the effects of the handlebar bag, and the wide tires to negate the effects of low trail. My current bike is a copy of a 40s "mule path" bike with 42 mm 650b tires and about 25 mm of trail. It handles fire roads and general riding beautifully, can be comfortably no-handed down to about 6 MPH, and gets a little bit nervous above 45 MPH. I find clamping the top tube between my legs gives me a bit more courage. As a home built frame, I doubt the alignment is up to professional standards, which may have something to do with it, but it is not a significant problem. Taking the bag off actually allows me to ride no hands at about 4 MPH, but the bike becomes unpleasant at above 35 MPH, with a bit of shimmy that I have never tried to "ride through".

And now you see why I consider the Paterek "two sentence explanation" to be a bit of an oversimplification. :)

Six jours, thanks for all that detail! Great description. I didn't mean to trivialize the topic - I recognize that my confusion with all the details of steering performance is a result of the topic's complexity.

I find my racy bikes reasonable to no-hand down to about 10 mph, as you suggest. I don't think I ever get much above 20 except on downhills. It sounds like at speed (10-20 mph) the rando bike with bag and 28 mm tires might have decent no-handing ability.

What do you think about a bike getting wheel flop at low speeds while going uphill? I seem to find this issue mitigated by more trail. Do you have any experience or ideas about that? It seems to run counter to the idea that with less trail there is less tendency to flop at lower speeds - or am I getting dyslexic again? It also seems like nose-up versus nose down is a significant factor. This sort of flop causes me concern because of traffic. I feel if I am flopping I am more likely to get sideswiped.

Road Fan

Six jours:

That was great. Thanks for taking the time to write it all. If you don't mind one more question: I have a Lemond, titanium frame, 90s vintage, road bike that handles just fine. I don't know the front end specs, but it has a carbon fork, so I'm assuming nothing out of the ordinary for a road/racing bike. I did a lightly loaded tour on it last year with a rear rack to hold my gear which was about 25 lbs. I also clamped two water bottle cages to the forks. No handle bar bag. I found that the steering had a pretty bad shimmy that totally prevented me from riding no hands or even riding with only a light grip on the bars. It didn't seem to be affected by whether the water bottles on the forks were full or emptly, so I'm assuming that the problem had to be the extra 25 lbs on the rear end. The shimmy was also more pronounced at certain peddaling cadences. I didn't notice that it was particularly speed dependent, but it was certainly a problem at my average traveling speed of around 15 mph.

I'd like someday to build a sport touring frame that could accomodate a lightly loaded set of rear panniers without having the same shimmy problem, while still performing well unloaded, say for century rides, etc.

What kind of front end geometry would you suggest?

Six jours, thanks for all that detail! Great description. I didn't mean to trivialize the topic - I recognize that my confusion with all the details of steering performance is a result of the topic's complexity.

I find my racy bikes reasonable to no-hand down to about 10 mph, as you suggest. I don't think I ever get much above 20 except on downhills. It sounds like at speed (10-20 mph) the rando bike with bag and 28 mm tires might have decent no-handing ability.

What do you think about a bike getting wheel flop at low speeds while going uphill? I seem to find this issue mitigated by more trail. Do you have any experience or ideas about that? It seems to run counter to the idea that with less trail there is less tendency to flop at lower speeds - or am I getting dyslexic again? It also seems like nose-up versus nose down is a significant factor. This sort of flop causes me concern because of traffic. I feel if I am flopping I am more likely to get sideswiped.

Road Fan

Frankly, I don't think anyone has a complete understanding of bicycle handling. If I'm being honest, I can think of at least one example to contradict everything I have said so far. For instance, you note that wheel flop seems decreased to you, at low speeds. This is the opposite of my experience, but obviously is no more or less valid. I think that bicycle handling is almost certainly the product of many, many factors, including body weight, positioning, and stem length. That is the only way I can explain so many different findings from so many people. At the least, it is probably fair to say that everything written about bicycle handling is a generalization and cannot be counted on as an absolute.

Can you elaborate on nose-up vs. nose down? Are you talking about the saddle? It does seem to me that putting more weight on your hands via a downward tilted saddle would change handling -- although exactly how I couldn't explain.

Fun, huh? :lol:

Six jours:

That was great. Thanks for taking the time to write it all. If you don't mind one more question: I have a Lemond, titanium frame, 90s vintage, road bike that handles just fine. I don't know the front end specs, but it has a carbon fork, so I'm assuming nothing out of the ordinary for a road/racing bike. I did a lightly loaded tour on it last year with a rear rack to hold my gear which was about 25 lbs. I also clamped two water bottle cages to the forks. No handle bar bag. I found that the steering had a pretty bad shimmy that totally prevented me from riding no hands or even riding with only a light grip on the bars. It didn't seem to be affected by whether the water bottles on the forks were full or emptly, so I'm assuming that the problem had to be the extra 25 lbs on the rear end. The shimmy was also more pronounced at certain peddaling cadences. I didn't notice that it was particularly speed dependent, but it was certainly a problem at my average traveling speed of around 15 mph.

I'd like someday to build a sport touring frame that could accomodate a lightly loaded set of rear panniers without having the same shimmy problem, while still performing well unloaded, say for century rides, etc.

What kind of front end geometry would you suggest?

Yikes. Way out of my league. I've ridden a bike with a five pound saddlebag, which was just fine. Twenty-five pounds on a rack is way beyond anything I have any experience with. Jan Heine has written of decent experience with a Mercian touring bike with a very slack head angle (70-71 degrees, IIRC) with typically moderate fork rake of perhaps 4 cm. I believe he said this bike was quite nice with a rear load and nearly unrideable with a front load. Overall though, I'd recommend you get advice from someone who actually knows something about it, ie. not me!

Oh, one other tidbit: I understand that wheel flop is exacerbated by a shallow head angle, and that reducing trail cannot completely compensate for it. (No, trail is not the whole story!)

So theoretically, at least, a 71-72 degree head angle is going to result in excessive low speed wheel flop no matter what else is involved. That may be why some people report low speed instability on certain bikes regardless of trail figures.

Oh, one other tidbit: I understand that wheel flop is exacerbated by a shallow head angle, and that reducing trail cannot completely compensate for it. (No, trail is not he whole story!)

So theoretically, at least, a 71-72 degree head angle is going to result in excessive low speed wheel flop no matter what else is involved. That may be why some people report low speed instability on certain bikes regardless of trail figures.

Ok, well my Woodrup, the low speed offender, has about a 72 degree front end, due to its smallish 52 cm frame size. Maybe this is one of the rarely-discussed compromises of small frames designed for 700c to 27 inch wheels. It also has a high BB, and a 74 degree seat tube. Maybe I should be going towards a French fit and base my brevet bike on a 55cm c-c platform in the first place, with a 73 degree head angle.

My purely personal opinion is that the upsloping top tubes, extended head tubes, and other tricks meant to get the handlebars high enough for long distance comfort are ugly and stupid. Going to a larger frame is such an obvious answer but between the weight weenies and the CPSC telling everyone they'll neuter themselves if they don't have at least an inch betwixt crotch and bike, it seems the fad is to make the bike as small as possible. Those foot long seatpost extensions still haven't stopped looking silly to me, but I'm told I'm a hopeless codger...

I've gone to the old "fistfull of seatpost" method and have been quite satisfied. I have never in my life felt the need to straddle a top tube with both feet on the ground, so really don't see the problem.

</grump, grump>

I've been riding since 1969, and I'm not on board with teh weight weenies and the CPSC. Safe fork ends are such a PITA, and since 1969 I've never failed to clamp my QR levers properly. That said, getting good geometry with a little more standover clearance is a good thing.

I don't think you can be a weight weenie if you are thinking about a reliable bike for over 100 miles at a shot.

I think Fistfull = French Fit, or at least more Gallic than I have now.

I also like this bigger frame approach because it will let me have a lower BB. I like how a 7.5 to 8 cm BB drop feels when pedaling.

I'd rather see a sloping top tube than some of the outlandish stem extensions I've seen. I'm of the "fistfull of stem" camp. Seems like most rando bikes have flat top tubes though. (Then I go to Rivendell and see this (http://www.rivbike.com/products/list/bicycle_models#product=50-700) with a sloping top tube and borderline stem extension. Oh well.)

I was looking at where I should put brazeons on my new fork. Didn't find any dimensions for the Mini Front from Nitto (http://www.rivbike.com/products/list/bags_and_racks?a=1&page=3#product=20-020) Also looked at the Velo Orange Randonneur Racks (http://www.velo-orange.com/vorarawiinde.html)which state that the attachment points should be 3 .75" below the bottom of the fork crown.

I'm also trying to figure out how the boss under the fork crown for racks and fenders is usually done. I've never seen one.

Aesthetically speaking, I prefer a very small amount of stem extension. Seems like most of the old French bikes were set up so that the stem was raised no more then a centimeter or so. My current bike has about three cm. of extension, which I don't especially like. The frame I am currently building is 2 cm. larger than my current ride, done mostly to solve that particular niggle. I suppose all of it is a matter of personal preference, but when I see six inches of stem coming out of a bike I scratch my head. C'est la vie.

I don't build a fork until I have the rack, brakes, and wheel that will be used. With the Nitto M12 rack I have so far found that you can actually bolt it to the cantilever studs, slide it into the fork crown, and mark the fork blades where the studs meet them. It's obviously a good idea to then remove the studs from the rack, attach the brakes to them, install the front wheel, and ensure that the brake shoes will hit the rim when brazed onto the previously marked spot, but for me the rack has located them perfectly so far.

I have not used the VO rack, but I note that Chris even mentions it's best to have the rack in hand when building the frame.

The standard French style fender mounting involves the use of a bolt with an eyelet in its head. The rack is inserted partly through the brake hole in the fork crown, the eyebolt is inserted into the crown, and the rack is then pushed through the eyelet and out the rear brake hole in the crown, where it is bolted into place. The threaded portion of the eyebolt now extends down from the fork crown and through the hole in the top of the fender, which is then bolted into place.

The only eyebolt I am aware of comes from Honjo -- Velo Orange has a good picture here (http://velo-orange.com/hodabofcreye.html) -- and is slightly too short, IMO. You have to compress the daylights out of the rubber or leather washer in order to get the nut to engage the first few threads. I've spent 20 minutes getting a particularly recalcitrant combo to work. For my next bike I am considering brazing a small bit of sheet metal to the underside of the crown and then placing a water bottle braze-on in the middle of it. I believe this is the way Toei does it, and it seems to me that would simplify fender mounting quite a bit.

<edit> Found a picture of the Toei set-up (http://www.jitensha.com/eng/frame_allrnforkdetl.html). http://www.jitensha.com/eng/frame_allrnforkdetl.html

thanks for the picture of the Toei, that's what I was thinking about doing. I thought the big washer from Honjo was to go in the steerer above the fender.

I'm not sure what I want to do about racks. I had a slim hope that there was a standard, but I guess that's not true.

If there is a standard I'm sure not aware of it. I think that's part of the whole "integrated" deal. Each part is "custom fitted" to the frame.

Paterek et al. oversimplify trail quite a bit, IMO. I agree with the Paterek POV when we are talking about narrow high pressure tires with no load. Beyond that it gets more confusing. There is little agreement, as can even be seen right here on this thread.

In my experience...)

Six jours---I have nothing to add to this, but I wanted to thank you for such an informative and thorough reply. On this topic I'm an ignorant putz who's trying to learn, and this helped. Thank you.

All the frames I have built for myself are exact copies of French randonneuring frames from the 40s and 50s. I have used them with 700c/30mm tires, and my current bike uses 650b/42mm tires.
Did you get the dimensions somewhere, or do you have access to the bikes in question? What do you think of the 650b tires? Is a bike set up for both 650b and 700c a realistic idea?

Bicycle Quarterly is an invaluable reference, as every bike review includes a line drawing with angles and tubing lengths. I believe volume 3 issue 1 is the one that contains a dozen or so drawing of various bikes, including Singer, Herse, and Routens. The Golden Age of Handbuilt Bicycles and The Competition Bicycle, both put out by BQ/Jan Heine also include line drawings for each bike. Everything I've built has been stolen from those sources.

650b is neat in that you use a smaller diameter rim and a larger outside diameter tire and end up with a total OD that approximates 700c/25 mm tire. There's no magic in 650b, and frankly, if the manufacturers would put out a lightweight and high quality road tire in 26" I'm sure that would work just as well. And if you have no intention of using a tire larger than 30 mm or so, I wouldn't bother with 650b. The advantage, as far as I concerned, is the ability to use unusually wide yet light and very high quality road tires, without toe overlap or other problems associated with gigantic wheels.

I believe it would be possible to set up your brakes so that they work with 700c wheels with the pads at the top of the slots, and 650b with the pads in the bottom of the slots. This would take quite a bit of care when locating cantilever studs (or setting fork blade length and brake bridge height, if using sidepulls) but does work in theory, I think.

<edit> It's actually volume three issue three that has all the great line drawings and a full discussion of low-trail geometry.

Good info thanks. I've been considering the low-trail geo but lack experience so it's nice to hear some. The further thing I'm wondering is how the front load height and weight affect the flop. I.e handlebar bags (high & light) vs low-riders (low & heavy). My touring (high trail + 35mm front tire) has the low riders. Wheel flop seems high...

northboundtrain in my experience shimmy is exacerbated by a rear loading bias. If the frame is big then on top of the load your own weight adds on to the rear...

The Golden Age of Handbuilt Bicycles and The Competition Bicycle, both put out by BQ/Jan Heine also include line drawings for each bike.
The Golden Age of Handbuilt Bicycles is coming out in a new edition soon. Amazon has it available for pre-order for $31.

That's interesting. Do you know how it differs, if at all, from the original?

Good info thanks. I've been considering the low-trail geo but lack experience so it's nice to hear some. The further thing I'm wondering is how the front load height and weight affect the flop. I.e handlebar bags (high & light) vs low-riders (low & heavy). My touring (high trail + 35mm front tire) has the low riders. Wheel flop seems high...

northboundtrain in my experience shimmy is exacerbated by a rear loading bias. If the frame is big then on top of the load your own weight adds on to the rear...

I have no experience with low riders either front or rear. I do know that a handlebar bag should be as low as possible, as the higher it is the more it contributes to flop. It's also worth noting that you want the bag as rearward as possible; that is to say, if you can keep most of it behind the front axle you will further minimize flop. I think this may be another aspect to the poor reputation handlebar bags have in some circles: the ones I do see are often mounted very, very high.

I've had a little shimmy on my Woodrup with a rack trunk on top of a Jim Blackburn rear rack, but only while descending. Load was 10-15 pounds. 5-10 pounds in a saddlebag without a bottom support causes no such problems. Even as stiff as a Blackburn is compared to an old Pletcher, I think the rack with load is acting as a pendulum or a weight on a springy rod - think a fly-fishing rig.

I wonder if the longer wheel base (i.e., longer chainstays) of a touring bike is the main factor in stabilizing and preventing shimmy. I'm thinking that the longer chainstays allow the rear load to be positioned further forward relative to the rear axle, which might minimize the tail-wagging-the-dog effect. I've used a proper touring bike with long (46 cm) chainstays with a rear load only, and while it doesn't perform as well as a balanced load, it certainly doesn't have the shimmy I experienced with the road bike.

a long wheelbase certainly helps with shimmy, but you have to have the front end sorted out too. My touring bike doesn't have quite enough rake and shimmys badly ( on edit: no hands only).

Something to thing about when chasing a shimmy problem. When you push an unloaded grocery cart fast the front casters shimmy like crazy, put a couple of gallon's of milk in the basket and the wheels calm down. In my experience I have solved most ( but not all) shimmy problems by moving the saddle forward and/or installing a longer stem to transfer more weight forward.

On my last bike I used low trail (51mm). With just myself ( no bar bag) on the bike the steering is very light. It gets a little twitchy on the down hills. However on slow climbs the bike is noticeably easier to ride in a straight line. There may be some correlation between the trail and the bike's intended speed/use when the constructeur build was popular during the late 40's through the 50's.

Jan Heine argues that a needle bearing headset can reduce or eliminate shimmy. There has been some disagreement on the point, however, and of course needle bearing headsets are getting hard to find. Once you have one, though, you should be able to use it for 30 or 40 years...

there was quite a bit of analysis of the dynamics of bicycles in the engineering literature. When I looked at it, I didn't understand the math. I should go back and look at it again now that has changed.

there was quite a bit of analysis of the dynamics of bicycles in the engineering literature. When I looked at it, I didn't understand the math. I should go back and look at it again now that has changed.


Look for papers and a website by Andy Ruina and Jim Papadopoulos. The main paper is titled something like "Linearized Dynamic Model for Bicycles" or similar. They also have a great literature survey, so you can deal with all the historical contradictions.

Be sure to report back, so you can 'splain it to all us old folks.

This is an old thread, but I like it so much I couldn't resist.

First, on stability, there is a new Science article which discusses how with enough weight on the front wheel, even negative trail zero rotational inertia bikes can stable. See Jan's blog, and don't miss Jim P's comments, with a link to detailed info (better than the Science article itself, which I read):

http://janheine.wordpress.com/2011/04/27/bicycle-stability-everything-works-together/

On the line drawings: my Golden Age of Handbuilt Bicycles does not have them, Only my Competition Bicycles does. Maybe the newest edition of the prior book includes them.

I was also intrigued to read in Bicycle Quarterly a ride report of a vintage Bone Shaker with a vertical head tube and zero trail. It was reported to be "easy to ride". It obviously had rotational inertia on its side, with a large heavy wooden front wheel. But that the trail was decidedly zero to good precision was intriguing to me, as there's a certain idea that trail is the whole story on stability. Of course the Science article shows its more complex than most would prefer: weight distribution is just as important.

the recent "science" article doesn't really address what is "important." They are talking about riderless bikes that are pushed. There is very little controversy over how bikes with riders work. The fact of the matter is that the different amounts of trail are a matter of comfort, not stability. At least in the technical meaning of "stability." I don't think that researchers are going to be able to characterize handling qualities of bikes, which is what the "high trail" vs. "low trail" discussion is really about.

I'm still no expert on the topic, but have increased my experience quite a bit since this thread was last current. At this point, I'm of the opinion that we may have been overthinking the matter of trail and handlebar bags. I've ridden super low trail bikes with handlebar bags, very high trail bikes with handlebar bags, and everything in between with handlebar bags. I could live happily ever after with any of them - provided the bags are mounted low and secure. Nothing works well when the bag is flopping around loosely from the handlebars!

Re. the line drawings in the Golden Age book - that's my bad. I hope nobody bought one on the strength of that suggestion. The Competition book is the only one with the drawings for every frame.

And a little tidbit: upthread I noted that I was going to try the Toei method of front fender mounting, with the bit of sheet steel brazed under the fork crown and a bottle boss brazed into that. I've since read that Jan Heine doesn't care for the arrangement (probably because the Golden Age builders didn't do it that way) but I've now used it extensively and think it far superior to the "daruma" method.

I bought it because you said it had line drawings. Good thing it's such a wonderful book.

Heh heh. Sorry, and you're welcome. :p

BTW, you might as well order a complete set of Bicycle Quarterly. I guess I've learned more about bicycle geometry from that source than I figured out in several decades prior.

I was looking at where I should put brazeons on my new fork. Didn't find any dimensions for the Mini Front from Nitto (http://www.rivbike.com/products/list/bags_and_racks?a=1&page=3#product=20-020) Also looked at the Velo Orange Randonneur Racks (http://www.velo-orange.com/vorarawiinde.html)which state that the attachment points should be 3 .75" below the bottom of the fork crown.

I'm also trying to figure out how the boss under the fork crown for racks and fenders is usually done. I've never seen one.

In regards to the Velo Orange rack, I just finished a new bike built on a Soulcraft frame, and he put bosses on the fork for the rack. The one thing different is that the shop owner that built the bike up is going to modify the rack for installation. We cut off the tang that should go under the fork crown, and instead, we will get special bolts from Paul that replace the mounting bolts on the Racer brakes, then braze on short legs to the rear of the rack that will attach to the extension bolts on the brake mounts. A similar set up is available for Canti brakes for Nitto racks. I'll put up pics once we do it. We were going to have mounting holes on the side or top of the fork crown, but the brake clearance would be an issue.

As far as bosses under the fork crown, I think it's usually a flat plate brazed in with a threaded hole.

I have that VO rack, and it was a complete PITA to install...even though I had followed the instructions to the letter on how to place the fork braze-ons.

Under-crown mounts for racks and fenders are simply a metal strap with a WB braze-on.

Pete

All the frames I have built for myself are exact copies of French randonneuring frames from the 40s and 50s. I have used them with 700c/30mm tires, and my current bike uses 650b/42mm tires. I have found that these bicycles do indeed handle better with a loaded handlebar bag than without. Without, they can be slightly unstable, especially at higher speeds. This is not a severe problem; a small shimmy at 25-30 MPH while riding no hands, for example.

Unfortunately, I have never ridden a high trail bike with a handlebar bag, so have nothing with which to compare.

When it comes right down to it, "randonneuring geometry" is nothing more than larger-than-normal fork rake used with the typical 72-74 degree head angle. The simplest way to get there from here can often be just paying your local builder $100 or so to re-rake your existing fork. That may well damage the paint, and it will also decrease tire clearance somewhat, but has been done with success. It's also entirely possible to have a new fork made for considerably less than the cost of a new frame.

HTH!

I have done this. My old Trek 610 (modified fork for added trail) has a trail just under 60 mm. I set it up with a 10 # or so front bag load, perched on a Nashbar-style front rack. It was possible to ride it with two hands, but required more grip on the bars. With one hand it was possible but difficult, only good on smooth road. No-handed it was scary. Later that same season I set up my (formerly mine) Woodrup with the same bag and rack. That Woodrup has rake about 56 mm and trail in the upper 40s. MUCH better handling with a similar load, and possible to ride no-handed, with no added fatigue with two hands. I could even operate DT shifters with confidence.

I'm sold on low trail for front loads, based on that test and on riding the Woodrup through the balance of last season. I sold it because I wanted a shallower seat tube angle. Currently I'm having a 65 mm fork / level frame made for the Trek 610 (73 degree head angle), and may go a similar route with a Trek 620 I just got.

My builder has been greatly delayed by the lack of acetylene, but seems to be back on track. Six Jours, are you willing to take on any fork raking jobs? I have another Trek with a stock fork, only bent when originally made, as far as I know. I'd like to have it adjusted from a stock rake of 55 to 60 or 65.