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  #1471  
Old 11-27-2019, 10:10 AM
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David Kirk David Kirk is offline
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Originally Posted by OtayBW View Post
How about handling characteristics due to fork/trail? Say someone likes high trail handling - other factors equal, do you vary tube selection here as well, or just fork and HT to get the desired characteristics.
I have to say: your forks are just awesome......
Do I change the tube diameter or wall based on the amount of trail being used? No.

I design the frame to get the proper fit and select the head angle to get the proper fore/aft weight distribution and then I match the fork rake to that head angle to give the desired trail. This is one of the larger reasons for wanting my frames to come with a matching fork - so that I can select the proper amount of rake to give the desired trail. When using a stock out-of-the-box fork I have to reverse that process....I need to design the frame to work with the generic fork and not the other way around. In some cases the end result would be fairly similar but in most cases it ends up being a compromise that I'm not comfortable with.

dave
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  #1472  
Old 11-27-2019, 10:43 AM
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colker colker is offline
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Originally Posted by David Kirk View Post
Good questions....I have just enough time before the lasagna comes out of the oven to respond.

The fork pictured does have a 1 1/8" steerer. Steerer diameter is chosen for a mix of performance and pragmatic reasons. If the rider is big and heavy and very aggressive that pushes me toward the larger size.....light and smooth makes me think smaller. Does the rider prioritize smooth ride over hammering? Smaller. Does the rider like to spring against his buddies for green signs like their lives depend on it? Larger.

The pragmatic consideration boils down to what size head tube does the frame have? If the tubing is normal sized and the frame is lugged then that pushes us toward 1" because nearly all quality lugs for OS sized tubes (the norm today) are designed for a 1 1/4" head tube so the steerer will need to be 1". Larger lugged frames that use XL sized tubes will use a 36 mm HT and this needs a 1 1/8" steerer. With fillets I can go either way.

One thing to keep in mind is that steerers come in different wall thicknesses too so a big guy who wants a smooth ride can use a thicker walled 1" steerer and the ride will be awesome and it will be way more than strong enough.

Fork blades - I have Reynolds make two different thicknesses for me and my JKS model so that I can fine tune the ride. My blades are my own part numbers and they are done a bit differently.....they look pretty normal on the outside but the inside is different and it cuts weight and gives a wonderful ride.

One last thing about steerer size.....it's not a phallic thing....bigger is not better. One needs to remember how we got here with massive steerers. For 100 years 1" steerers were the norm and life was fine. Then the mountain bike came on the scene and the loads were higher and the forks got longer (more leverage) so the steerers got bigger to deal with these loads. A bigger steerer was indeed a good thing here. The steerer material changed to aluminum and carbon and to deal with stiffness and fatigue resistance the steerers got even bigger and tapered. Again - a good solid engineering reason for the change. But just because these "standards" worked well in other applications and materials doe not mean that they will be better in steel. Full. Stop. One needs to pick the right specs of a tube based on how it's going to be used and what the material is and not out of some misplaced sense of being modern or fashionable. It just doesn't work this way.

Time to check on dinner - thanks for reading.

dave
Good stuff... I was the one who asked 39T and reading this makes me smile. If i am going for a high end frame it better be custom and if it´s custom the guy who builds it better build me a steel fork too. It better be David Kirk.
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  #1473  
Old 11-27-2019, 01:54 PM
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AngryScientist AngryScientist is offline
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Some excellent insight in the last few posts, thanks for that Dave.

This is the kind of discussion that reinforces the value of having a bike made to measure by a master craftsman who knows what he's doing.
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  #1474  
Old 12-04-2019, 09:18 AM
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David Kirk David Kirk is offline
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Not long ago I had the privilege of building a special frame for my friends at Savile Road to bring to the Philly Bike Show. The frame was fillet brazed and built with the 100th Anniversary tubeset made by Columbus to celebrate that milestone. One of the fun features of the tubeset is the seat collar cut with the Columbus Dove. My painter Joe Bell had some fun showing off his airbrush skills making the dove pop. He’s pretty damn good.

dave



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  #1475  
Old 12-04-2019, 09:20 AM
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Hilltopperny Hilltopperny is offline
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Quote:
Originally Posted by David Kirk View Post
Not long ago I had the privilege of building a special frame for my friends at Savile Road to bring to the Philly Bike Show. The frame was fillet brazed and built with the 100th Anniversary tubeset made by Columbus to celebrate that milestone. One of the fun features of the tubeset is the seat collar cut with the Columbus Dove. My painter Joe Bell had some fun showing off his airbrush skills making the dove pop. He’s pretty damn good.



dave









That is gorgeous Dave! Is it on Display at Saville now?


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