Cycling UK Forum

My first wheel was a 36h 4-cross. I wouldn't recommend that combination - the spoke angle at the rim is really bad, even with a small flange hub.

Most tandems will also have some sort of attachment for the reaction arm of the Arai. If it has a disc mount instead, there is an adaptor available.

This page is excellent:

http://www.precisiontandems.com/arai.htm

Marathon != Marathon Plus.

There are three problems with Marathon Pluses:

1) Very heavy
2) Hard to fit
3) Some riders report the bead breaking and strands of steel puncturing the tube.

Rolling resistance is worse, but probably due more to the thick sidewall. They're a good choice for a Brompton, where rear wheel punctures involve a bit of an odyssey.

SJSC sell the tiny brass washers (2.5mm, I think) which can be used to pack out an over-long spoke elbow. They're vital on thin steel hub flanges.

I'd love a Sturmey AM or AC hub, if there's one in there. The AM is a 3 speed medium-ratio (about 15% up and down from "normal) and the AC is close-ratio (about 6% up and down from "normal"). Derailleurs killed them off, but they were designed for club cyclists and time triallists respectively.

Do you have a drag brake (Arai drum) as well? With only two rim brakes, you'll need to be careful of rim heating on long descents.

CO2 has saved me from a long walk home three or four times. One 16g canister will get a narrow 700c tyre very hard and a 2" MTB tyre hard enough to ride.

You can work it out by estimating the volume of the tyre (pi times the square of the radius times the mid-circumference of the tube - do it all in metres). 16g of CO2 is roughly 8.75 litres at normal temperature, so divide that by your tyre volume and you get the number of atmospheres' pressure.

E.g.:

23mm 700c tyre is about 1 litre, so you get 8.75 atm or 130psi.

2" MTB tyre is about 3.7 litres, so you get a less impressive 2.4 atm or 35psi.

They're busted

Seriously, I've never seen this kind of damage, but you get a similar effect with an unlaced rim (I've done it to old ones cut out of a wheel).

They must have improved them. The picture of an ACI elbow in Tony Oliver's "Touring Bikes" book was shocking.

DT also lengthened their elbows to match their own range of hubs, but shortened them most of the way back after complaints.

I always use d/b on both sides, and have never broken (or even loosened) a spoke, except in a major prang.

Plain gauge spokes have no advantages except cheapness. There are, however, single-butted spokes which may have an advantage on the drive side, because they have a thicker elbow (the same as the major diameter of the thread, which is about 2.3 mm and only just fits through the hub spoke hole), which is where you need the extra metal.

I'd have DT Competition 2.0/1.8/2.0 out of preference, and Sapim if not available. ACI aren't supposed to be as good because the elbow doesn't hug the hub flange properly (unless you put a brass washer under the head, which is a faff and just adds weight).

Avoid "rustless" and chrome-plated spokes. Also beware of black spokes - the DT ones are dyed stainless steel and are fine, but those on cheaper bikes are painted steel and will rust eventually.

The bracing angle is important, and this depends on the flange spacing and the amount of dish (for a rear derailleur or disc brake wheel). If the spokes come into the rim with a low bracing angle - nearly vertical - the wheel is less able to withstand side loads. That pothole wasn't a side load though!

Generally I'm with Jobst Brandt - build a wheel with the spokes as tight as possible, but ensure it is below the pringle limit. If you take it too far, the wheel will assume a soft pringle shape - don't worry, it's elastic deformation - when you do a final stress relief job by squeezing the spokes hard, and you'll need to back them all off. Something like a Mavic MA3 will cope with very little tension compared to, say, a DT rim, where the limiting factor is simply that the spoke nipples become too stiff to turn.

Shock loads like a pothole can only reduce spoke tension, not increase it. Maybe that Chrina rim wasn't built as tight as it could be, or it was built as tight as possible for the rim design, but that still wasn't enough. If the spokes in the area of the impact ever go into compression, you're in trouble.

I hit a pothole this year which was big enough to give me a snakebite puncture in a 145psi (yes, really - Fortezzas are good for 165psi) rear tyre. The wheel was fine, though.

I have a SON 28, a SON-XS for the Brompton and a new Shimano DH-3N80 (couldn't find it in the UK - try roseversand.de). This latest Shimano hub is much lighter than the SON and appears to have less resistance with the lights off. It's also half the price.

www.oldbiketrader.co.uk has just got an original ASC in, yours for £180. Apparently it feels nothing like a "real" fixie, because there is a fair bit of slop.

4kg for a 531 frame? They should be about 4.5 pounds. Or did you include the fork, BB and headset?