31,740 reputation
13083
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location Minnesota, USA
age
visits member for 3 years, 1 month
seen 36 mins ago

Old, tired, crazy.


29m
comment Can I replace my bicycles dynamo with batteries?
As RoboKaren indicates, most dynamos are AC. The LED lamps may be designed such that they depend on having AC, or may just blindly rectify the "juice" such that they won't notice that it's DC. One tricky issue is whether they depend on having AC to perform voltage regulation (not unlikely given that a dynamo has such variable output). If they depend on AC to enable the regulator then they may well self-destruct when powered with DC.
3h
comment Can I replace my bicycles dynamo with batteries?
(BTW, rechargeable penlight batteries are a PITA. And keep in mind that they run about 1.2v each.)
3h
comment Can I replace my bicycles dynamo with batteries?
If the lamps were old-fashioned incandescent lamps it would be simpler -- you'd just need to match the battery voltage to the RMS output of the dyno. But with LEDs it's harder to say. Probably you could use batteries of approximately the same voltage, but it might not work, and it might set the whole bike (OK, only the lamp socket) afire.
3h
comment 2,600km on an 8 speed bike?
@Blam - Actually I think he should purchase it legitimately. ;)
8h
comment 2,600km on an 8 speed bike?
I'd say 200km a day is overly ambitious. 100km would be more realistic.
17h
comment Annual technology gap of high end road bikes
@Blam - Just the fact that hobbyists have been making electric shifters for years.
21h
comment Annual technology gap of high end road bikes
An electric shifting system is simpler and likely lighter than mechanical, and hobbyists have been building them for at least 5 years. The added cost is probably about $50 currently and would drop to negative once volumes get up there. There are very few reasons (other than Shimano blocking the way) why all bikes would not be electric shift in a few years.
22h
comment Damaged (scraped) tire - what to do?
If the cut were to open up and he got a blowout it should still be possible to "boot" the tire (usually a relatively new dollar bill, folded twice, works well for this). But of course that would require some skill the OP likely does not have.
22h
comment Damaged (scraped) tire - what to do?
Impossible to tell for sure, but it does not appear to be a serious cut. Unless you're in a situation where you must avoid a flat if at all possible, I wouldn't worry about it.
22h
comment Annual technology gap of high end road bikes
@DWGKNZ - What R&D cost? The R&D was done by hobbyists.
22h
comment Annual technology gap of high end road bikes
(I would guess Shimano can make electric shifters for at most $50 more than mechanical ones.)
22h
comment Annual technology gap of high end road bikes
You will see electric shifters on Wally World bikes within 5 years (probably sooner). Then the price for decent quality ones on decent quality bikes will drop to a reasonable level.
22h
comment Annual technology gap of high end road bikes
The only advancement in technology for the past 5 years or so has been electric shifting.
1d
comment What's the lowest safe cadence on a climb?
@R.Chung - I don't know how you'd be able to calculate the maximal force, since even the best cyclist's stroke is not smooth, especially at low RPM. You might calculate, say, RMS force, but that could easily be off by 2-3x.
1d
comment How to inflate a tire with a Presta valve?
There is no need to depress the stem in a Presta valve, since air pressure will open the valve when the pump develops more pressure than is inside the tire. All that's necessary is to briefly tap the stem before putting on the chuck, to make sure that the rubber gasket is not stuck closed.
1d
comment How to inflate a tire with a Presta valve?
The purpose of the threaded stem and nut is to hold the stem out so you don't have to do the thumb thing.
1d
comment Solid rubber bicycle tires
Also note that there are several different technologies that produce tires that are far less prone to puncture (like 10x to 100x less) than are the standard tires that came with your bike.
2d
comment What's the lowest safe cadence on a climb?
I don't have the physiological data/knowledge to figure this out. One problem is that, even with good seat height, the knee is bent at a fairly sharp angle when the maximal force is applied, whereas when walking/running (the most-studied activities) the knee is at a much shallower angle. I did find this, though I didn't attempt to digest it: physicaltherapyjournal.com/content/67/9/1365.full.pdf
2d
comment What's the lowest safe cadence on a climb?
When you're doing that wattage on the flat you're applying a much lower force to your knees. Wattage = force times RPM.
2d
comment Mystery item broken on old Dawes. Help!
Ah, yes, it's a simple cable clamp. A good bike shop will probably be able to scavenge one from their spare parts box and should give it to you for free or a modest price.