Motorcycles have far greater complexity than a humble, Chinese mass produced, carbon fiber, weekend warrior's, road hack and its supposedly "weight saving" obscenely overpriced, decorative bling! Simply pouring away half the contents of your carbon-fiber-caged water bottle will save far more weight than the thousands of dollars you just wasted on "upgrading" to this season's "latest and greatest" groupset! [Until the next season's unmissable and unavoidable updates]
Cut-away image borrowed from the Trykit website [with permission] The part labels are my own. The left axle pawls are identical but hidden by the freehub body.
Of course the friction I measured is a worst case scenario. My trike's top gear is 48T x 12T. So it represents a 4:1 increase in axle friction measured at the pedals. My Stronglight cranks are only 160mm c-to-c which slightly exacerbates the difference compared with standard 170-175mm crank lengths.
Can I really feel the difference in axle drag while pedaling at high rpm in a modest gear on the 38T middle chainring? I feel I do but really can't be certain. Many cyclists will spend a fortune trying to reduce all potential losses in their drive train with the latest ceramic bearings. They will then suspend all further disbelief and shell out a second fortune on weight saving measures. While simultaneously ignoring their own weight and fitness levels.
My understanding of cycling efficiency is that the rider's weight is far more important than that of the bicycle itself. I drag a heavy canvas saddlebag around with me everywhere. This itself is always loaded down with a heavy U-lock. I am often carrying a great load of shopping in addition. It may seem strange but I rarely notice the extra weight while riding. Rather, I judge my own climbing performance on the day. It is often a shock having to carry the shopping/sports bag indoors. I wonder why I did not notice the extra weight on all the steep hills I have just climbed.
Only very rarely indeed have I stripped a trike to its bare roadworthy minimum weight. Then headed out for a ride completely intoxicated by the utterly amazing improvement in performance. It cannot be said that I am overweight myself. At least not any more. Riding a trike is a weight and drag handicap anyway compared with most bicycles. Few today would consider riding a bike with sporting pretensions which weighs as much as a lightweight trike. My Trykit weighs about 13kg when stripped of its usual and essential "shopping trolley" junk. Not bad, but racing bikes in its price bracket are considerably lighter.
If reducing bearing drag makes me feel a noticeable improvement then perhaps I don't really need scientific proof. Any more, in fact, than the vast majority of deluded and often overweight cyclists, who think the expense of their toys is a rational use of their disposable funds. But then, what is? A car? A hole in the road into which you throw money? Just to be allowed the right to sit sweating and and fuming in a gridlock traffic jam? While the planet goes to hell and those nasty, idiot and socially inferior cyclists whiz effortlessly by on either side?
Sunday 10th 62-72F, 17-22C, overcast, rather breezy already. It is supposed to gust to 30mph+ for most of the day with rain or showers later. I suppose I should feel myself lucky compared with the UK. Where 2" of rain fell in an hour in Cambridge. With many roads flooded. A trike may be more stable on flat surfaces but has a wider track and a lower bottom bracket. You may not wobble as much as on a bike but you have three wheels to find hidden drain covers and kerbs beneath the murky waters. So an outing on a flooded road is not the most sensible of journeys on either machine. I still think I'd prefer the trike. Since wellington boots with SPD cleats are rather rare one might like to consider polythene bags over the feet just in case.
I left early without my usual coffee and rolls to get some miles in before the wind really picked up. Heading straight into the wind is always a good idea while one is still fresh. I kept extending my route until I had looped all the way around to have the wind on my back for the last leg. It worked too! So the load of shopping had climatic assistance for the last few miles. Lots of broken branches and twigs on the road from yesterday's blow. With even higher winds forecast. The trike still felt faster than before the axle mods. I'm busily rethinking the Shimano 10sp sprocket spacing to match the Campag Ergo 11sp levers. It will have to go back on the stand while I record how well it changes between gears. 32 miles.
Pm. I spent an hour this afternoon stripping the rear axles again. I double checked the distance between the axle inner ends in case I had been mistaken. Even without the Trykit freehub in place there is still no play in the axle bearings when I waggle the wheels at the rims. So I am confident I have not overdone the thinning of the central shim/spacer. Though it should be remembered that each of the half axles is individually mounted in two bearings retained by circlips.
The hollow axles have left a clear mark on the central 4mm spacer.
A slight difference exists in the spin down time of each axle with the wheels mounted. Though I don't believe the small difference is really worth pursuing now that the wheels spin so freely. My Higgins, fitted with Trykit 2WD, has always been exceptionally free running. I was instructed to set up the [adjustable] axles to leave 4mm clearance between them. For some reason my Trykit trike had non-standard [fixed] axle spacing from new. I delayed doing anything about it because I imagined the friction caused by the larger axle bearings on the Trykit trike were causing the problem. The rear wheels spin for minutes now and it is much easier to spin them up to a high speed in top gear. [48x12]
It has been blowing a gale since lunch time but no rain so far. Promised to be even windier tomorrow!