Tech Talk
Powermeters for the Masses (or I can afford this and still eat)
Powermeters have been one of the most talked about advances in training over the past few years. There are no drift problems associated with HR or environmental changes associated with speed. When I do an interval at 300 watts, its 300 watts. So why doesn't everyone use a powermeter? The good ones cost between $1500 and $4000 dollars, some require you to build them into a wheel, and they are bicycle electronics so my expectation is 1-2 years before it breaks.
I am always open to new ideas, I have been following this one for a few years and I belive they have got it right. The I Sport from I Bike is a $199 powermeter that really works, especially for triathlon. It is not perfect, , but this may be a good alternative for the serious athlete on a budget. $199 gets you the basic unit with a wired speed sensor. The mounting kit will absolutely not work on a tri bike with aero bars, it is meant for a road set up. I purchased a Minoura Swing Grip mount which works very well. The mount is as important as the unit. It must have a clear view of the air mass in front with no disturbances. The unit is very simple, it uses a pitot static system, much like in the jet that I fly, to measure altitude, incoming wind speed, temp, etc.. It then uses this information along with your own personally entered data to calculate watts. How accurate is it? VERY! It is also consistent, so that even if it is actually a few watts off, who cares, as long as it is consistent, I know how hard or easy I just went based on my baseline calculated with this unit.. I have been using it for a few weeks now and it works well. The Minoura mount makes it work better than my original setup. Negatives? There are a couple. The speed sensor is not great mounting wise, its not really a good fit on any of the forks we use, but it works. The unit itself feels a little cheap out of the box, but once its mounted it seems more secure and works well. As for longevity, time will tell, but to be honest if get 1-2 seasons out of it for this price I will be happy.Of the 4 other more expensive powermeters we have installed for our customers, only 2 still work. The 2 that broke required new bottom bracket units at $800. We did not sell them and neither unit is still in service. So, if you have $199 to spend this may be a good alternative, its easy to read and use, it has big numbers for us old guys, and its not hard to calibrate. See you at the races, Josh
I Sport Power meters are now available through us for $199. The mount for a tri bike is an additional $25. Please call to order, I expect to have them in stock by 12 Dec. 08.
A forward view or the I Sport Powermeter. The air inlet is the small hole in the front. It is mounted on a Minoura Swing Grip which is very secure..
A top view of the unit through the aerobars.
New Wheels
We have recently found some problems with matching up the newer and faster 23mm rimmed wheels with alot of the recent carbon bikes. This is due partially to the rediculously close tolerences in the seat and chainstays and partially to the fact that carbon is not magic. It is plastic and the resins will give and flex due to the riders weight over time. I recently witnessed a high end frameset that gave 3/8" with a 130 lb rider aboard and made the seatstays rub the decals on the rim. This frame was 1 season old. Remember, the pros get a few new bikes a year, you don't if you are like the majority of us. That kind of flex is absolutely unacceptable. Think of all of the wasted energy on race day. Rest assured that all of the new wheels fit on our bikes when you buy them, and for the rest of the time that you own them!
Ceramic Bearings?
Lots of manufacturers have been pushing ceramic bearings lately, so I decided to do a little research and see if there was really a difference, aside from the price. I did a little checking for background beginning with the Rolls Royce Jet Engine Rep at work, I am an airline Capt.. He informed me that ceramic bearings are designed to be used at super high RPM (our jet engines turn at over 30,000 rpm so we actually measure it in % instead of RPM). They are much more resiliant to high tempurature and last alot longer than the original metal bearings used in Jet engines. I asked him if he could see an application to using such bearings with a much lighter load at 90 rpm. He said no so I decided to see for myself.
My Ultegra SL cranks were beginning to look a little worn and the bottom bracket had over 5000 miles on it so a liitle change was in order. I decided to try a set of SRAM Force Carbon Compact cranks with the same gearing I had removed. I replaced the standard Ultegra SL BB with a new SRAM Red Ceramic BB. I broke in the ceramic BB for about 50 miles before the test. I used my powermeter on a closed loop where I do most of my training. I used an average wattage of 180 and rode each in the same gear for 1/2 hour. My average cadence was 91 for both and my speeds were identical.. So what is the difference between the 2 sets? In my mind about $200. I could see no advantage to ceramic bearings. I do however like the new cranks they feel a stiff as my old Shimano Alloy cranks and add a liitle carbon bling to my bike.. The SRAM BB requires regreasing every 100 hours and it sells for about $230 . The standard stainless steel BB sells for about $40 and I just throw those away and replace them once a year.
