Saturday, June 27, 2009

Inexpensive Tandem Hub

Since I am too cheap to buy an expensive tandem hub (at least for the cheap tandem I am working on), i modified a track hub. Dual threaded for freewheel and drum brake. The Miche hub worked nicely for several reasons.
1. More threads, more nicely done, than other track hubs. As many threads as on a normal hub. I don't want to "strip" the threads with the extra power of a tandem.
2. 12x28 bearings. The bearing are large enough to handle the extra weight of a tandem, while still leaving enough aluminum thickness on the hub, and allow a 12 mm axle. Any other size and you in danger of burning out bearings, breaking the hub shell, or bending axles.
3. Allows the use of an inexpensive but strong freewheel. I know freehubs are great, but since the ratchet pawls are at a smaller diameter, they can't take the same amount of abuse a freewheel can. Obviously a phil wood hub would work great, but they are over $400.

Made an axle for the hub. Not hard to make, other than having to be ultra careful to get the axle to bearing a slight slip fit. The non drive end I made of aluminum. The axle ends, still needing a trim, I silvered into thick tubed 1/2" 4130 tubing, that i then machined down to 12mm.

2014 comments..  Hmmmf.  looks great, but didn't work out in the end.  My favorite tandem rear hub now is siply the $40 or so Shimano 29er (629 ?)  cassette hub.  With 10mm steel axle.  Has held up great for us.  Drum brake ?  sold long ago.  Just not necessary for us..

Friday, June 26, 2009

Pa and Oh visits

Been in Allentown PA for interaction / training with the Pro Pump Services guys. Been here nearly two weeks. Visited two Powerplants, a foundry, and our Sulzer service center. Here we are at Cogentrix plant in Northampton that burns waste coal (basically coal that was "dumped" and is sitting in piles around Pennsylvania).

Here we are measuring vibration on a booster pump (a small pump, yes relatively, this is a small pump). I have the blue hardhat on.

I managed to make a quick trip to Ohio for the weekend to see Joel Sharon Caleb and Cameron. Here are the boys playing golf. A lot of fun. Here Caleb is getting the ball back to the green after launching if off the tee well beyond the the green and into a hay field. This was Cameron first time swinging a real golf club and he did quite well! Even managed to skip the ball off the water.

2014 comments :   These guys are big boys now ! 

Friday, June 5, 2009


With the new digital TV, I was able to watch the Giro. I noticed slideouts occurring on corners with dry pavement. Watching the riders go down, it was apparent what went wrong: Not enough weight on the front wheel.

If you watch carefully, just prior to the front wheel slipping, the rider's weight is back on the saddle. One can find all kinds of information on how to corner, the majority of course good advice, but I have yet to see emphasis on, or to keep awareness of the weight balance between your wheels. I do have personal experiences as well (e.g. a crit in michigan in 1993? second to last corner my front wheel start sliding. In hindsight I am pretty sure I was pedaling/pushing so hard that I also pushed back into the saddle. I did stay upright, but scared the guy behind me .)

With a tweaked front geometry and by coming out of the saddle a little on corners, I have found I can corner better, and have hit nearly 60 mph on roads in west hills here in portland ( only possible if you stay in a full tuck, don't touch brakes in corners, and of course weigh as much as me...)
From BLOG Pictures

If you take a motorcycle training class, quite a bit of emphasis is put on cornering. One key point is that in most situations if you lean the bike over (done by an initial countersteer) and look into the corner, the bike will turn. And that speed (within reason) is not the issue, if you lean it, it will stick. (Assume dry pavement...I am always wary of wet roads ! )

The same with a bicycle. If you lean it, look into the corner, you will stick. But that assumes you have the front wheel properly loaded. It is easy to transfer weight to the front wheel, come out of saddle and put weight on the pedals. Inside pedal, outside pedal doesn't really matter, likewise, what is happening to your weight side-to-side, or up-down doesn't really matter compared to your fore-aft weight. Weight on the pedals means most of your weight vector is now at the bottom bracket which is nearer the center of the bike, and viola, with the rest of your weight on the handlebars, your front wheel will be sufficiently loaded with weight and slideouts should not occur. (on dry pavement and assume no pedal clip.)