Monday, October 27, 2008

More on the 747

747 refers to the tubing used on this bike. The tubing is standard diameter. By the numbers, standard is actually non-standard now. Almost all non-custom steel bikes are made with over sized tubing, which is still called over sized even though it's the standard on nearly all steel production bikes.

I like standard steel tubing because it flexes a bit more, well, a lot more in my opinion, than over sized tubing. I've talked about standard tubing before -- see item #2 where I go on about Alex's Ivy Cycles bike.

Anyway, both of my RB-T's use standard tubing. So does my Trek 520 and my Trek 720. In all those cases, the wall thickness of the tubing is 9/10ths of a mm at the end and tapers to 6/10ths of a mm at the middle of the tube. This tapering is referred to as "butted" in the bike world. So, when referring to the tubing wall thickness on these bikes, you could say they are 969's. (Actually I think the 1983 version of the 720 may have been 858 -- and I sometimes wonder if the 520 is 181).

In any case, that's where the 747 comes from. It's really thin-walled tubing. In today's world of ultra-stiff over sized aluminum bikes, this 747 would likely be referred to as "noodley." I love the way that feels and I no longer try to convince people of its greatness. It's a bike that gives back when you climb. It feels right to me and the first time I really felt it was on my 1991 RB-T.

So the goal with this 747 is to have a fast bike for long day trips with minimal stuff. It will have fenders and it will have a small rear bag. It's 73 HT and 73 ST with 50 mm of rake, so it's a solid mid-trailer, which will hopefully mean lost of fast and fun cornering.

I still need brakes for it. So I've not ridden it yet.

Dig this:

That's Scott and Oscar's new fancy tandem. I was at 2 Wheel Transit during lunch time today and saw this beauty ready to roll. It's the Co-Motion Periscope: a full size tandem that can fit just about any sized person on the stoker seat. In addition to a super-sloping top-tube, the rear stoker seat telescopes to fit someone as short as 3' 6" to a six-footer.
It's a great tandem for these two. Oscar is about 7 now and has totally outgrown the trail-a-bike.


Anonymous said...

I am going to call your bike Perry 'cause is periwinkle.

bleckb said...

I saw Scott yesterday and he told me about the new bike. Looks nice. And thanks for all the dope on the new bike. Should be a fun one to ride.

Anonymous said...

did you get gran bois tires for it?

John Speare said...

Rory: yep. The 28 mm cerfs. I've finshed the build and got honjos on it. I've ridden it a bit and it's wonderful. Today I'll take a longer ride and try climbing some favorite hills. Stand by.