I was watching Tour de France coverage on TV this morning, and wondered how many gears their bikes have these days - it's been a long time since I paid much attention to bicycle technology, and I figured it would be more than the old fashion ten speeds I'm used to. I looked it up, and apparently they commonly have 24 speeds these days - 12 sprockets on the rear wheel and 2 on the chainwheel. I had no idea...to fit that many on the wheel, I assume the individual sprockets and the chain have gotten much thinner? Otherwise the geometry of the chain would be pretty extreme in certain gears.
Chains started getting narrower when they went to 10 cogs across the back, I know 11 speed went a bit more again but not sure what happened when they added one more to get to 12. On the mountain bike side as they added gears on the back those gears just got larger and larger, they actually didn't need to go narrower (or as narrow as road) as the larger gears meant there was more space between the largest cogs and the spokes for the derailleur to do its thing.
On the industry side of thing it's a good reason to sell you a bunch of new gear as they go one better every few years.
Yes the chains have gotten thinner. My mtb has a 1x12 and it's 5 years old... commonplace tech these days.
Mountain bikers became allergic to front derailleurs a while ago, so they needed all their gears on the back :) Then the roadies took advantage.
Now check out the brakes...
They had to go to disc brakes because friction brakes on the rims would over heat the air in the rims that was already +100#. Those long downhills in the mountains...
11 & 12-speed chains are not only narrower, but they also allow for greater misalignment to account for the wider cassette.
It was an option on my gravel bike to have a 2x12. Pretty easy retro fit if I wanted to do it. It's pretty common overall. Looks like the rotors are the same size as those on my gravel bike as well.
If you really want to get fancy, Bianchi makes their replica bike for 17.5K or a handful of race ridden bikes sold for just under 30K a couple years back.
Wow, 24 speeds sounds like a lot, but I'm also not a pro cyclist, and I know some of those mountain stages are steep.
Could you imagine a car having that many gears? 
Colin Wood said:
Wow, 24 speeds sounds like a lot, but I'm also not a pro cyclist, and I know some of those mountain stages are steep.
Could you imagine a car having that many gears?
They've basically got a high range and a low range. A Dodge 1500 comes with an 8 speed auto, so that's 16 speeds right there.
The need for so many gears is explained by the complexity of using a human to power a bicycle as efficiently as possible in every circumstance from climbing up a 12 degree mountain at 1 mph to speeding down a 12 degree mountain at 60+ mph when the engine's sweet spot may be between 90 and 100 rpm. 
Purple Frog said:
They had to go to disc brakes because friction brakes on the rims would over heat the air in the rims that was already +100#. Those long downhills in the mountains...
This sounds a lot like the hear management issues the F1 has.
The weight of Tour de France bikes counting grams offbrand article (Accuracy?) Measuring everything in grams and a 14lb bike is crazy to me having steel and aluminum bike. I wonder if they didn't have the rule how lightweight they could go with bikes.
Purple Frog said:
The need for so many gears is explained by the complexity of using a human to power a bicycle as efficiently as possible in every circumstance from climbing up a 12 degree mountain at 1 mph to speeding down a 12 degree mountain at 60+ mph when the engine's sweet spot may be between 90 and 100 rpm.
That's a really good point.
I finally have a newish 1 x 12 drivetrain on my mountain bike. Sooo much simpler. Only 1 derailleur and 1 shifter and 1 cable (they can pry my cable from my cold dead hands.... my bike doesn't need a battery).
Between the 1 x drivetrains, tubeless tires, and now (semi) radial tires, my bike is as efficient as my old cross country bike and has 2 times the suspension travel and WAY more comfy!
In reply to trigun7469 :
The used road bike I picked up in may weighs 17lbs. Riding it feels like cheating.
I road my MTB this morning(which climbs way easier than my previous ones), then hopped on the road bike for a ride with SWMBO this evening. It just takes so little effort to ride vs. any other bike I've ridden.
In reply to trigun7469 :
There is a UCI minimum weight of 6.8 kilograms which is just under 15 pounds. This is supposed to keep the teams from making bikes so light they are dangerous.
Riders can choose if they want 1x or 2x drivetrain. What's crazier is that yesterday in the TT, Pogi and Roglic were running 1x with 60 tooth front rings. That's banannas
In reply to Pete Gossett (Forum Supporter) :
Switching from Steel to Aluminum felt like cheating I can't imagine going to CF and other lightweight components
In reply to SEADave :
The article I posted talked about appealing that rule and make it open. Safety stand point I am guessing that wouldn't appeal it in this day and age.
In reply to Purple Frog :
Some of the vintage small bore GP bikes back in the day had the same problem, several had 8 and 9 speed transmissions to make the most out of a 50cc engine that could turn 15000+ rpm. Kind of wild to think about.
I got my first 1x drivetrain a couple years ago, for MTB it is wonderful. I finally got it geared (and got myself in good enough shape) to where first is low enough and I can crank up things, but every once in a while on a fast open downhill or riding on pavement, it sure would be nice to keep the cadence a bit lower. I think road bikes will probably always need that dual range capability or some kind of hub overdrive or something since they have to go faster but still have some pretty aggressive climbs.
budget_bandit said:
Riders can choose if they want 1x or 2x drivetrain. What's crazier is that yesterday in the TT, Pogi and Roglic were running 1x with 60 tooth front rings. That's banannas
Ahem, Remco and Roglic were actually on 64t rings yesterday! Remco was running a 64/10, and hit a top speed of 74km/h, or 46mph. Pretty wild what the pros can do on a TT bike.
In reply to golfduke :
I feel like I'd need a while before feeling comfortable riding a bike that fast, but I suppose most of the riders have been building on their experience for many, many years.
Colin Wood said:
In reply to golfduke :
I feel like I'd need a while before feeling comfortable riding a bike that fast, but I suppose most of the riders have been building on their experience for many, many years.
One of the most terrifying-yet-exhillerating times of my life was at NH Motor Speedway. They do a monthly road bike race on the track, usually the road circuit. But one day, for some reason, they let us run the full mile long oval. 15 laps on a banked track with perfect tarmac. Toward the end, we had an 8 rider paceline, absolutely full gas and spun out on gears, and I looked at my wahoo and saw 36mph. On flats. One crossed wheel and the whole heap was going down in a yard sale, but damnit if it wasn't the best feeling in the world.
I still, viscerally remember that feeling.
Too many years ago I started riding for fitness,I need to start that again but I digress...
My routes started with 10 minutes out ,constant pedaling,I don't recall the RPM.
When I quit I was up to 1 hour out and back,anyway one of my routes had a down hill and of course up hill. I decided one day to see if I could "run out of gear" on the down hill...well at 25mph I decided that me in near underwear plus road plus 15 miles from home seemed like more pain than I wanted to deal with. I had a blow out at only about 15 on the front and that was more fun than I wanted. So 40+ mph is more than impressive.
They have non-UCI hillclimb events where guys have built bikes down below 10 pounds...
https://www.bikeradar.com/features/pro-bike/2022-hill-climb-bikes
SEADave said:
In reply to trigun7469 :
There is a UCI minimum weight of 6.8 kilograms which is just under 15 pounds. This is supposed to keep the teams from making bikes so light they are dangerous.
You can get a caad 10-13 down to that weight with some parts and that is not a light frame. My 12 year old carbon made with bastard parts is about 1lb off race weight and I am not a small person.
Going from aluminum or titanium to carbon was a game changer for me. But the big thing is the new brakes. I was just before the disk brake era and it makes everything just that much safer in a group. Especially downhill.
