I'm ordering a Waterford frame, probably something similar to their series 14 sports touring model, and I'm trying to optimize the design. Dave Moulton has a couple of blog posts on trail and effects of trail on high speed shimmy. He says that he "always built my bikes with at least 2 ½ inches (63 mm) of trail", and he found that the bike was sluggish or wandered if he increased it more than that. Thw Waterford sport touring specs have 60 mm of trail, the road sport has 58 mm. Anyone with experience on this have a opinion on whether it makes much difference varying this in the range from 58 to 63 mm?

I've also looked at the Specialized Diverge, the trail varies from 64 mm in the 48cm frame to 56 mm in the 61cm frame (because the head tube angle is steeper in the larger frames). Dave thinks that larger framers are more likely to shimmy, so it seems you would want the larger trail on those frames. I'm guessing that they use the steeper head tube angle on the larger frames to keep the wheelbase shorter.

GailT, I can tell you that trail is a tough subject to know and that there are opposing opinions.
My Cannondale works well unloaded and loaded front only, rear only, or both F and R.
Trail-54.6 mm
Fork rake-54.1 mm
Head tube angle-72°.

Brad

There also are theories and opinions on how trail affects weight distribution (front vs rear loading).

You were talking to the custom bike manufacture that has more experience than everyone here combined. Do you think asking here is better than talking to experienced people at Waterford?

Ask the fine folks at Waterford, they know what they are doing. It's not like they have lineage to Ignaz Schwinn and the Paramount line or anything like that. Plus in the limited emails I have had with them in the past they are super nice.

One of my dream bikes is a Waterford lugged out to the nines in Reynolds 953 stainless steel.

Loading front panniers helps a lot.. one thing about touring frames , main triangle flex is less with a 9/8" top tube than a 1"

and likewise the down tube 1.25" vs a 1.125" one...

Thanks for the comments. My current bike is a 1991 Cannondale ST600, 25 inch frame with the same specs that you listed. It is a stable and generally pretty comfortable, somewhat harsh on road bumps, which maybe I could improve with larger tires, but other components also need updating and I think it makes more sense to invest in a new bike for longer rides and keep my Cannondale for shorter rides commuting/around town. I'm also looking for more of an endurance type frame, I'm 57, and planning for a bike I can ride for the next 25 years. Maybe I'm over analysing it, but given the option to customize every dimension of the frame I want to dial it in as much as possible.

I'm still working on the dimensions with Vecchios, and asked them to increase the trail from 58 to 61 mm, also increase the wheel base from 1028 to 1060 (compared to 1085 on my Cannondale), and the new bike will also have higher stack and shorter reach than the Cannondale. I confess I don't know anything about frame design other than what I've read on the internet in the last few weeks, maybe just enough to be dangerous, and I'll rely on Vecchios to stop me from doing anything stupid. I'm hoping the increases in trail and wheelbase makes sense for my priorities for stability and comfort. Thanks.

IMO rule no. 1 is that if you trust someone to build a frame you have to trust them to design it properly. If you don't trust them that far, find someone you do.

The folks at Waterford earned their reputation, which is probably why you'e going with them. So, why would you take the opinion of a bunch of strangers on the internet over theirs?

Just to be clear, I'm not asking you or anyone else on BF to design my frame. I'm interested in learning more about the trade-offs in frame dimensions, I found Dave Moulton's blog posts interesting and helpful, and expect I can learn a lot from people who have much more experience than I do, I think the longer wheelbase suits my needs better than the original design and the the frame designer agreed that was a reasonable change. You seem to imply that I should have just accepted the original design and not asked any questions and not try to understand the reasons for the design.

You're reading too much into it. It's not that you must accept his original design, it's that frame design isn't a place fora bunch of kibbitzers. Fork geometry goes hand in hand with steering axis, and to a lesser extent with wheelbase and weight distribution.

So, while you need to tell the builder your objectives, and maintain a dialog, you have to trust him to bring the elements together using the expertise that brought you to him in the first place.

I don't build frames, but I build custom wheels, mainly for folks who've had bad luck in the past. They'll often come to me with a bunch of specs, and I stop them early on, explaining that I want them to tell me what problems they've had, and what they want from the new wheels, but then let me decide how to deliver on that.

My own designed custom heavyweight IGH has 70/ 70 angles, 46.5 WB, 1.25" tubes and close to even weight 49/ 51. At first the fork had 70 mm rake and 53.5 trail. It did not want to turn. With 30 lbs or so in the back, it both wobbled and shimmied and broke with the drum brake. The new tandem weight fork has 66 rake and 61.2 trail. It now takes any corner at any speed and is solid at 46 mph. It is fine without load but it still has a bad shimmy at any speed no hands when loaded. My guess is it is an inch too long and steerer is too slack and too heavy of course at 120 lbs. ha

If you are going to carry baggage, either front or rear panniers, handlebar bag or saddle bag, or any combination of these, you should discuss this with the builder. Maybe you can ride bikes with various geomtries to find the one you think is perfect.

You might consider asking the mods to move this thread to the Framebuilders subforum to get some additional opinions.

Before you finalize the deal, try to figure out if you will have toe overlap or not.

I have toe overlap on all my 700c bikes with frame sizes around 58 to 59 cm but do not have toe overlap with 26 inch wheel bikes of comparable frame sizes.

I have fenders on all my touring bikes, I do not know if I could get rid of the toe overlap by removing the fenders, but I value the fenders too much to try. Toe overlap is not a deal breaker, but it is an inconvenience that is nice to avoid if practical.