To no useful purpose, in terms of calculating gear ratios. Bearing in mind that if you or the bike put on weight, the tyres will be slightly more compressed or as tyres get worn their diameter will be slightly reduced. Presumably, tyre pressure varies with air temperature and the barometer. Everything must be different in say Mexico City, compared with somewhere like Cleethorpes.
Bear in mind you are posting here in favour of binning sprockets smaller than those which meet your personal approval. Except when they are OK for bikes with small wheels.
I'm not even in the slightest suggesting smaller sprockets, not even for small wheels.
Not in the slightest.
Bigger sprockets and bigger chainwheels please. Bring back 13t sprockets and bring back bigger chainwheels ............ 53t and 54t please for 700c. Moulton has a 61t with (ha! ha! 20" wheels?) 18.3" rolling diameter. About 10% wrong.
This thread is about stuff that should be binned.
IMHO, it is smaller sprockets .............................. and also poor generalising systems for calculating gear ratios with no regard to rolling diameter of the rear wheel.
Extremely thin band clamps to save 3g of weight on a shifter, so anything over 3Nm is risking breaking it... then calling it "top of the range" and charging a fortune for it...
This is what they used to be like and should be like, 100% bombproof...
We'll always be together, together on electric bikes.
Mick F wrote: ↑23 Jun 2021, 2:08pm
I'm not even in the slightest suggesting smaller sprockets, not even for small wheels.
Not in the slightest.
Bigger sprockets and bigger chainwheels please. Bring back 13t sprockets and bring back bigger chainwheels ............ 53t and 54t please for 700c. Moulton has a 61t with (ha! ha! 20" wheels?) 18.3" rolling diameter. About 10% wrong.
This thread is about stuff that should be binned.
IMHO, it is smaller sprockets .............................. and also poor generalising systems for calculating gear ratios with no regard to rolling diameter of the rear wheel.
You have to understand that you save a few grams here and there with smaller sprockets and chain rings and never mind about them wearing out more quickly than the larger items.
I have owned a tandem with a Rohloff hub since 2012 and a single since 2016 and no longer care about the problems with derailleur gears.
The issue (other than wearing out) is that smaller sprockets are less mechanically efficient.
I'm willing to bet that any tiny weight-saving is spoilt by less efficiency.
It's always puzzled me that Doc Moulton, who was well-known of carrying out multiple tests on prototypes, should adopt that super-small rear wheel sprocket (ie 9 or 10 teeth). It is (was) very unlike him to rubber-stamp anything that didn't meet his high standards, almost always based on physical measurements, not whim or fashion.
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
Bigger chainrings start to get in the way if you're using shorter cranks and if you need a shorter and/or wider chainstay.
The shift to single ring set-up on MTB and CX/gravel bikes opened up a whole world of possibilities with frame design, especially placement of pivots on full sus MTBs.
Road seems to have settled on "semi-compact" (36/52) chainsets as the best options after a lot of faffing around with the dreadful compact (34/50) and the "traditional" (39/53) is largely confined now to the top end groupsets.
Most groupsets now operate on vastly bigger cassettes than "traditional" - when I was racing the options were 12-23 or 12-25!
Now it's normal to have 11-30, SRAM do a 10-33! A lot of rear mechs come with bigger jockey wheels than previously as well. There's the gain in efficiency right there. Losing a few teeth on the chainring is negligible.
27 is a constant. It allows a rough comparison between set ups. Nobody says "I require a penny-farthing wheel of exactly 115.328 inches to match this gear ratio".
24" - 108" is about a standard MTB range, 33" - 122" is about what you'd expect with a compact double.
Also crank length is completely ignored so its not an exact indication of the MA anyway.
rareposter wrote: ↑24 Jun 2021, 10:03am
Road seems to have settled on "semi-compact" (36/52) chainsets as the best options after a lot of faffing around with the dreadful compact (34/50) and the "traditional" (39/53) is largely confined now to the top end groupsets.
Is 36/52 really that much different from 34/50 ??? (it's less than 7%, at most) Why better, and why so much better?
(just asking out of interest - I don't see me buying a double in the near future ... )
doubled triangle/diamond frames that's not to say they haven't been useful, and they shouldn't disappear, but with modern materials they aren't necessary and are holding back cycle design now. remember the Boardman/lotus bikes had the UCl not banned it we might be riding some very different creations today. So what I wnat to put in room 101 really is the UCI regulations
NUKe wrote: ↑24 Jun 2021, 3:00pm
doubled triangle/diamond frames that's not to say they haven't been useful, and they shouldn't disappear, but with modern materials they aren't necessary and are holding back cycle design now. remember the Boardman/lotus bikes had the UCl not banned it we might be riding some very different creations today. So what I wnat to put in room 101 really is the UCI regulations
Two problem with this:
- if you mean CF by "modern materials", it's a nightmare for the environment. And
- if you want the UCI to allow modern/faster designs, then will you allow recumbent designs?
(imagine the bike-swap possibiltiies mid-TT !!! )
My bikes use a range of 700C wheels with effective diameters ranging from 26.7" to 27.25". How many people can genuinely feel a difference of 1% in mechanical advantage or velocity ratio? Since it is common to express gear ratios as a tooth count ratio, e.g. 52/18, 27" seems an entirely satisfactory wheel diameter to assume to convert to gear inches.
james01 wrote: ↑23 May 2021, 2:21pm
Top of my list is "Lawyer's Lips" on front forks. I have a special list of foul oaths for the bright spark who invented them.
You'll appreciate them if the front wheel ever works loose.
NUKe wrote: ↑24 Jun 2021, 3:00pm
doubled triangle/diamond frames that's not to say they haven't been useful, and they shouldn't disappear, but with modern materials they aren't necessary and are holding back cycle design now. remember the Boardman/lotus bikes had the UCl not banned it we might be riding some very different creations today. So what I wnat to put in room 101 really is the UCI regulations
+1 perhaps if we had rejected UCI regulations years ago, we wouldn't have had to have witnessed that horrific bicycle crash in the Rio Olympics 2016.
I still don't understand why these regulations are not simply rejected. No one owes the UCI anything, and actually we're all free to draft our own rules about bicycle racing if we want and invite others to join in. The UCI is like some stupid stage hypnotist, making everyone believe that we're chickens.... or like the magician in the Wizard Of Oz. The moment you stop believing, is the moment they lose their power over you.
Last edited by cycle tramp on 24 Jun 2021, 4:38pm, edited 1 time in total.
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