J.Higgins 

Wow, Thanks, Rob! I appreciate your chiming in here. I need all of the help I can get. Right now, I am leaning towards milling down the BB to the proper width (I'm thinking 73mm), filling in the threads with brass, then rethreading it to 24 TPI. I may forgo this last step in favor of using some Loctite red threadlocker. Look at it this way - I'll probably never have to change the BB ever again, and if I do, well, I can always go the VO threadless route.

I'm becoming tempted to simply braze on some bosses to accommodate some nice linear-pull brakes. When I get the time, I'll grab a cheapie disk hub and see how it fills the space between the rear stays - just to see in my mind's eye if a brake boss will work with the existing geometry.

Also, thanks a bunch for the link to your bike build. I haven't seen it yet as of this writing, but I'll pop in there when I am done and check it out. Thanks again!

Rob_E

Yeah, I just went the threadless BB route from the start because it seemed the cheapest and easiest of all the options because I didn't have to take it in to the shop for rethreading. And I didn't have to by expensive, Phil Woods, English threaded caps. Taking a hacksaw to my bike was worrisome, but it worked out. I figured I could always go the rethreading route if the VO threadless bottom bracket didn't work, but it worked fine.

J.Higgins 

Which NuVinci model did you get, and how do you like it? What made you get that over a Sturmey Archer? Price? Quality? Curious...

Rob_E

It sure wasn't price. The Nuvinci is considerably more expensive, usually. I think it was the N360, and I got a deal on it that brought it closer to the SA 8 price, but with normal pricing it's more than twice as much. I got it because I was running a Nuvinci on my other bike, so when the deal came along as I was trying to upgrade the Twenty, it seemed like a good idea. And maybe it was...

It has more range than an 8 speed hub. On the other hand, the Nuvinci is heavier than just about any other hub on the market that I'm aware of. The shifter is also a lot more fiddly. The range is great, though. I think it sits between the Alfine 11 and Rohloff for range, but I haven't looked that up in a while. I love the shifting of the Nuvinci more than any other hub, too. It's just the set-up that can be tricky, and some aspects of it you have to deal with every time you remove the wheel.

My rational was that it wasn't going to be easy to figure out a front shifting solution, so if I packed enough gear range in the back, it wouldn't matter. That mostly worked, but I geared it too low, and as a result it was a pretty pokey bike. That was an issue I was going to address one day with some cog/chainring changes. It was also supposed to be possible to add a drum brake to the Nuvinci, which was going to solve my rear brake issue. Unfortunately, even after cold-setting, clearance was too tight for the drum brake.

I read somewhere that lately Nuvinci is not doing great financially. If you consider a Nuvinci hub, I would not count on the warranty. I had two hubs and I think they each had warranty issues at some point. Nuvinci was really good about fixing or replacing them, but if they go out of business, you just have to hope the hub lasts. Fortunately, a lot of people have put their hub through its paces and not been able to break it.

So, yeah, gear range and consistency between my bikes. I have since stopped switched my full-sized bike to an Alfine 8 hub, and my folder has a Nexus 8. For most of my riding, 8 gears has been enough, and I think if I were setting up a Twenty again, I go 8 speed with a coaster brake. I like limiting the number of cables you have to deal with when folding the bike, plus there's the whole brake-compatibility issue on the Twenty. If I had no intention of taking it far, I might go with a 2-speed hub and coaster brake. No cables to the back at all.

J.Higgins 

Which leads me to consider that a disk rotor would also be out of the question, and I would be better served to look for an alternative.

Also, can you tell me what is your chainring/rear sprocket tooth-count?

By using Sheldon Brown's calculator, set up my 451 rims, 170mm cranks, a 40T front, and a 20T rear, I would get 71.6 and 19.9 gear inches, respectively. Not bad in my opinion, but of course I have no idea yet what sprocket tooth counts are available, so I just put these is to see where my ballpark gear inches would be. I'd like to plug in your numbers to see what you came up with.

fietsbob

A Sturmey Archer 4 speed (like the heavier 8 speed) is 1:1 first & 3 overdrive gears..

Greenspeed in Australia re Machines Sturmey Archer Drum brake front hubs Mostly for their Recumbents, But ..

They also are the Brompton distributor for Australia and rework the SA drum brake hubs to fit a 74 axle width fork..

given the hubs are 36 hole the skipping 1 hole in 3 a 24 hole rim can be used .. (my Bike Friday Tikit does this for its rear IGH)
[Sram i-9]


..

Rob_E

No, I can't remember and don't have it written down.

I had the parts at hand to replicate my full-sized bike gearing, so that's what I did. Result was that with the smaller tires, my gearing a little too low. But I don't remember the numbers. Neither bike is available anymore for me to check.

J.Higgins 

Thanks, Bob. I'll keep that in mind. The 451 rims I have are 36H. I'll just use them all.

J.Higgins 

Fair enough. I think I'll be able to get a range of 20-80 if I can do my math right. Plenty for a wee bike like this. The big problem is spreading the rear stays and getting it right. Lots of tweeking.

fietsbob

Just find The P/V Pump head for my Silca Track pump harder to use with a narrow gap with small wheels ..

I have Schrader valves on the 349 16" with 28 spokes .. the 24 on the Tikit has more room so It has P/V tubes

... Seems when S/V tubes in Brompton sizes are out of stock , P/V remain available..


maybe 451 rim will have more space (sir Cumfrence) than the 406 on the Bike friday (32 spoke on that, here.. )

The BMX bikes on the shop floor as I recall are close spoked ..

but having the 48 hole option for the real heavy BMX Stunt action it's worse..





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