Minion

Is anyone looking for a lift from Joburg to the OFM Classic in November? Anyone offering a lift? I don't feel like driving by myself, so I can offer a lift or else catch a lift if someone's got space and wants to split petrol costs. I can take two more people and one more bike (two extra bikes if you can provide an additional Thule rack).

This is another reason I'm a big fan of training wheels with high spoke counts. I you lose a spoke on a 20 spoke wheel, it may well be an end-of-ride event. I managed to lose a spoke on my 32 spoke Open Pro and, after a little bit of truing, I was still able to ride the 50km home. I even did it at close to full training pace.

They appear to be failing due to a product defect so, on the plus side, you can return them for a full refund.

Look for something with lots of spokes (32+) in a standard size and material (e.g. double butted steel). Higher spoke count improves durability, standard spokes make it easy to replace them if they break 10 years from now. Make sure it has brass nipples - alu nipples will eventually seize and make it impossible to true without cutting spokes. On the rims, look for something with double eyelets. These make the spoke holes a bit more durable. On the hubs, look for something that allows you to service and grease the bearings periodically. Look for good quality steel bearings. Avoid fancy ceramics or cheap Chinese bearings. There's a bit of a compromise here: good quality cup and cone bearings will last a very long time if well maintained, but you can't really replace the races once they wear out. Cartridge bearings won't last as long but can be replaced when worn. Stay away from anything that uses light weight as a selling point. Weight should be the last factor to consider on a durable training wheelset. Personally, I would go (and have gone) for a custom built set of 32 or 36 hole Mavic Open Pro rims with 3x spoke pattern, standard Sapim of DT Swiss double-butted spokes (e.g Revolution or Laser), brass nipples and good quality hubs (e.g. Shimano or Campag).

Damage caused by shifting into the spokes would nick the spoke and create a potential place for a fatigue crack to grow. If the mis-shift caused the breakage, you would see the spokes failing at the point where the RD hit them. Right side spokes may be more likely to fail since in almost all hubs they transfer most of the drive forces and so experience a higher stress state. In addition, the right flange is closer to the centreline to accommodate the cassette. This means that the right side spokes must have a higher tension than left side spokes to get the correct dishing.

Speak to Johan Bornman (www.yellowsaddle.co.za) to build the wheel properly. Aside from catastrophic events, spokes break due to metal fatigue. This is why it takes a while for them to break. You may have to replace all of your spokes now as the rest could also be reaching their fatigue life.

Did you actually have to pay this amount? On a duty free item you shouldn't have to. I brought in a wheel and some other parts last year and it worked out to: CRC Invoice value: GBP 686.30 Customs value: R 8239 (at a SARS rate of 12.0049 R/GBP) I had to pay SARS: VAT: R 1268.67 (14% of R 9063: R9063 = R 8239 + 10%) Clearance fee: R 30 Total: R 1298.67 I have bought a lot of stuff from overseas and the VAT on duty-free items has always been 15.4% of the customs value. The customs value has always been the invoice value times the SARS ROE. It's a little bit unclear where SARS gets its ROE from. I brought in items in September and December last year and both times they charged R12.0049/GBP. In September, the market rate was around R11.7/GBP and in December it was around R13/GBP.

Doesn't seem to be much interest. I think I'll make a call depending on what the weather's like and how I feel when I wake up tomorrow.

At current fitness, I don't think that will be a problem.

It looks like the race goes past the south boundary of the reserve, so it shouldn't be a problem. And it still leaves Saturday and Monday, anyway . Ps. congrats on your Fittrack competition victory.

I'm thinking of doing a Suikerbosrand ride this weekend. Anyone else going or keen to join? At the moment my plan is to head there on Saturday 22nd, but that's not set in stone.

I'm also going to have to give it a miss, I'm afraid.

Parking is easy to find. Come in through the north gate and keep going. You'll see where it is. http://goo.gl/maps/AA1vh It takes about 40min to get there from near the Joburg Zoo.

I think I'll also join you guys on Sunday.

I'd like to thank Garmin South Africa for the excellent service I received last week Thursday. The HR strap for my Edge 800 died and I took it in to their service centre in Honeydew. It was out of warranty and I was prepared to pay to have it repaired or replaced. I was extremely happy when they gave me a new one on the spot and also declined my offers of payment. That's exceptional customer service. Well done, Garmin SA .

Most amazing, closest race I've watched. 0.32s separating the top 3. Wow.

I agree with you that the quality of an instructor should be judged by their ability to convey their ideas, not necessarily their own skills at implementing them. In my personal experience, some of the best lecturers and teachers I've had were not research leaders, but they were exceptional teachers. I've also been lectured by at least one professor who was one of the leading experts in his field, if not the expert and he obviously understood his material, but just couldn't explain it in a way that we could understand.

Ahhh, so the event they were holding was the Joe Low Solo Cycle Challenge. "Good day cyclist, jogger, walker, rollerblader, you are advised as follows: Cycling today Tuesday 31st of JULY 2012 has been cancelled due to an event being held on the track untill late, Thank you for your kind co-operation."

It would appear that it's not just HR, but also includes HR variability (based on an answer to an earlier question I asked). Presumably you're paying for the algorithm and research that map HR and HRV to power in the cycling context and not just a HR monitor strap. Given your own raw HR and HRV data, it should be possible to generate your own algorithm to make this estimate. The downside being that HR monitors that can record HRV are comparatively expensive and data intensive.

This is good to know. The PowerCal is looking like it would work very well for what I'd want to do with it. I'll certainly look at getting one once you've got more available. TSS ends up being proportional to NP squared, so the error is further magnified, but if it's consistent like with average power, it can also be calibrated out to some extent.

The HR readings are identical except for a 2bpm difference in the one average, which could be due to slightly different start and end times. This would be because they're both getting the same HR data stream. The speed and distance would be different since the PowerTap speed and distance would come from the hub vs. the PowerCal speed that's probably coming from GPS measurements. The PT cadence reading can also come from the hub, while I suspect there was no sensor for the PowerCal (mean, min and max are all 127, suggesting a glitch). The Edge 800 rounds each elevation point to the nearest whole number (if you look at its elevation track, it has a stair-step shape), while older models like the 310 record decimal values (giving a smooth profile). So, while the 310 might record an elevation change from 100.4ft to 100.6ft, the 800 would record 100ft to 101ft. This can cause issues with the cumulative elevation calculations.

I see the TSS value for the PC is around 15% lower than the PT. Is this a consistent trend across your rides? Also, is the difference in powers consistent, or is the PC sometimes higher than the PT?

I currently ride with a Quarq and Powertap on my road bikes. I plan to start MTBing again, often enough that it will have a significant effect on my cumulative TSS, but not often enough that I could justify the cost of a brand new MTB power meter. My HR strap is also on its way out, so a PowerCal could be a viable replacement. In this scenario, I would be looking to combine the 'relative' power values from a PowerCal with the absolute values from the Quarq and PT in my overall TSS calculation. My concern is that while the PowerCal may give reasonable TSS and IF values when used in isolation and compared only with other PowerCal values, the estimation may not be acceptable as I'd be using it together with sessions with directly measured power values. On a technical note, for my own curiosity, do you know whether it uses HR variability in it's estimation (there's quite a bit of ergonomic research that indicates HRV might be a good estimator of task effort).

This seems to imply that the PowerCal would not necessarily give a good estimate of actual power, but would give a better estimate of IF and TSS. Is this what your testing shows?

I presume you've contacted the various clubs around Gauteng? Most of them have pretty set routes that they use often. For example: http://www.crestawheelers.co.za/ClubRides.htm