For a 650b rando bike to be used with 40+mm tires with fenders, so I'd really like something with 50+mm clearance. Have checked Nova, Sachs, Henry James, and Ceeway, and will use Ceeway's sloping cyclocross/tour crown if neccessary, but I would prefer a traditional flat crown if I can find one. Anyone know of any?

I think Kirk Pacenti might have one . google the name and you should find his website

Ah, forgot about him! Thanks for the tip; we'll see if he's got what I need.

Kirk ha a brand new mega crown, but it's pricey. So two good things really.

Well, he tells me that his crown has about 44 mm of clearance, which will make it useful for another project I have in mind, but isn't quite going to cut it for this one. The search continues...

I thought Curt Goodrich had built an MTB fork with a Pacenti (mega?)Crown that had about 60mm between the blades?
Oh well, it is easy enough to make your own plate crown if you have a good drill press, Wicks aircraft supply has small pieces of 4130 plate to work from.

here is an example of a triple plate crown http://bp1.blogger.com/_9eq98ghZfUY/RhgobJbnacI/AAAAAAAAACg/1qyyvZKgtqg/s1600-h/IMG_3478.JPG

I'll be using a 1" steerer with standard blades, so that limits my choices a bit.

I hadn't even thought about a plate crown, but that's a very traditional choice and I'll definitely look into it. Thanks!

There was a pic on the frame forum last week. Can't find it now.

Plate crowns are an interesting option: http://platedforkcrown.blogspot.com/

Yeah, I found that site while searching a little while ago. Interesting stuff. I'm tempted, but as a newbie I'm a bit nervous about killing myself with a handmade fork crown. Richie may have a crown that will work after all, but I'm not convinced. We'll see...

Sachs says his beautiful "Newvex" crown will work. I have my doubts, but I ordered one anyway. Even if it's not wide enough it will look great on some other project.

Thanks for everyone's help.

NewVex is 47mm between the fork reinforcements, plenty wide for a 40mm tire .

Thanks for the spec. I'm concerned that things are going to be tight with a fender, though.

width is not what you need to worry about, A 40mmm tire under a 45mm fender width is plenty coverage. If you want to use 50mm fender width you can pinch the fender. What you really have to watch out for is your clearances under the fork crown. buy the fender and the largest tire you plan to use before you make anything including the main frame. Do a mock-up of the fork with the largest tire you expect to use with your fender in place.

+1 I agree with all that about vertical clearance and getting the parts and building your way up from them.

I would be a little leary of having that little space on either side of the tire. Are we talking around 1/8" inch? It would be a tad wider than that at the widest point of the tire. Even on road trips, I have picked up enough mud on rail trails that it almost zeroed out my fender clearance. I also had a rear tire rupture once, which created a significant wobble, and had to replace it with a low pressure tire that was very fat. I also have had trouble fitting cantis on bikes that are too narrow in the forks, limits the geometries you can use when trying to get decent performance with road levers, and makes it impossible to drop the wheel for fixing a flat with some blocks, unless you remove at least one side. The sloping crown, EVR-FC-CX-286, is 61mm, and they have several in 1", because I accidentaly got shipped one once.

One of the reasons I started building my own bikes was that you can't get nice fender lines on "stock" bikes unless you are using the largest tire the bike was designed for. So I don't start building until I actually have the tires/wheels that will be used on that bike, and I give a lot of attention to getting the fenders just so.

Moreover, I prefer to have at least 8mm of clearance between tire and fender, which means I really need at least a centimeter of clearance between tire and fork blade. Obviously, 47mm - 40mm = less than 2 centimeters total clearance, but depending on where the crown was measured and how far down the crown/blades the widest part of the tire ends up, along with how far above the tire the fender is located/where the sides of the fender end up in relation to the sides of the tire...

So the Sachs crown might work, and it might not. We'll see. I know for a fact there are several sloped crowns that will work, so that's my fallback option. I just love the look of the flat crown. Sure wish I could find one made for the narrow round blades that came on some of the nicer Herses, Singers, etc.

Here is where I screwed up on a fork when I built a randonneuring bike last year. Because I wanted the classic French randonneur handling I went with 42mm of steering trail. I wasn't noticing that the resulting 60 mm of fork offset was pushing the wheel center farther away from the fork crown thereby increasing the angle between the bottom of the fork crown and the fender( see the blue lines on the pic). Because I wanted a tight fit and the fender contoured to a 40 mm tire I only allowed for 3 mm of adjustment.

When the frame was finished and I went to assemble the bike I discovered I no longer had 3mm of fender adjustment! I was actually 2-3 mm short of having enough clearance between the top of the tire and the fender. So I had to file a little off the front bottom edge of the crown to compensate.

http://home.nycap.rr.com/richboat/crown1.jpg

http://home.nycap.rr.com/richboat/crown2.jpg

FWIW, the Sachs crown arrived today, and while it's gorgeous, it's not nearly wide enough. It'll look great on the 700x30 rando bike, but I guess I'm going to order the wide sloping touring crown from Ceeway for the 650x40 project. Oh well...

FWIW, the Sachs crown arrived today, and while it's gorgeous, it's not nearly wide enough. It'll look great on the 700x30 rando bike, but I guess I'm going to order the wide sloping touring crown from Ceeway for the 650x40 project. Oh well...

If by chance you bought the stainless steel Newvex crown, The reinforcement tangs may not be stainless steel. Mine weren't, I had to fab my own from stainless .