Drivetrain Math
 

If you have a cheap drivetrain an expensive drivetrain with identical gear ratios int he crank and cassette, strictly speaking about power output of the drivetrain only, is there a difference?

I ride for the workout and not concerned with speed but my ego does get deflated when I am passed by someone. Mostly on hills and I upgraded my drivetrain to 50/34 11-28. I get passed a lot on slight inclines. My entire drivetrain is like $100, and my bike is an OLD Mangusta 5000 (made by Mongoose back in the day).

I know their bikes are $3K-$6K passing me but how much better can they be? Although I am in great shape, I am certain these people are just in better "cycling shape" and just curious how much modern bikes contribute to speed aside from the drivetrain.

There may be a tiny difference. But it would be so small as to not be noticeable. You'll still get passed! A higher end DT may be smoother/quieter and shift better though.

Only one way to find out... bust out the wallet!

I sold Mongoose bikes, including their road and off-road bike, in a bike shop in the 1990s, but I don't remember the Mangusta 5000. Just looked it up; nice bike.

Many riders go all out to pass people and then turn off onto another road and poke along at a snail's pace while gasping for breath.

I still have PRs set on a mid 80's, lower end steel Panasonic thanks to its straight gauge 4130 tube set. Silly stiff with over inflated 1-1/4" tires at 100psi. 6 speed rear. Hill climbing beast.

I don't think there is much difference strictly in efficiency between lower and higher end drivetrain components (probably there is some, but I'm sure it's negligible); it's more about, weight, durability and smoothness of shifting. Well maintained (clean and properly lubed) vs neglected drivetrain make more difference.

That said, riding up inclines it's mostly about power to weight ratio, so either those passing you are putting out more power, weigh less (together with the bike), or both.

It's the motor.

If you put a Ferrari transmission into a Fiat 500 and made no other changes do you think it would go 150 MPH?

Sorry, couldn't resist. A buddy had a X 1/9 back in the day and that thing went through transmissions faster than tires.

As the great racer said "don't buy upgrades, ride up grades". Agree with the others there may be slightly less driveline loss but not as much as say skipping the mid ride burrito.

Some guys on here argue the proper chain lube will turn you into Lance himself. Over the course of a ride it may make a cumulative difference in total energy spent, but going uphills there are bigger things at play.

You said Math..
 

Ratios is the math.. chain ring # of T turns hub cog T in a ratio .. like say 2:1 pedals turn once wheel turns 2x.
if crank and hub cog is the same size then its a 1:1 gear , then the other factor is wheel diameter..


then there is air resistance .. there is a formula for that.

$$ spent per MPH is not applicable unless its not human powered ..







...

Any number of reasons for why someone passes you - too many factors to address, really - power, weight (rider and bike), skill/technique, aero etc etc. All these things being equal, the only things that rob power are tire friction (rolling resistance), wheel bearing friction, BB friction, chain friction and jockey wheel bearing friction. I imagine that, short of going with ceramic bearings or something equally high-zoot, well-maintained, well-adjusted bearings, either loose ball or cartridge, are going to be close enough to make little difference. Tire friction? - lots of info out there about the benefits of wider, softer (up to a point) tires on rolling resistance. Chain? maintenance and chain line - a well-maintained, straight chain is a more efficient chain. I would say that a well maintained, well adjusted cheaper drivetrain will be essentially as efficient as a similarly maintained and adjusted expensive drivetrain - the expensive one will likely shift better and be lighter, but more efficient? Not so you'd notice.

The question I gave is if you are getting passed while in the 34-28 gear. If yes, then you might want to go with a lower gear cassette like a 34t.

There are all sorts of reasons why you are getting passed, but they all point to not being as strong a rider. So, give yourself a lower gear and maybe you can keep your cadence up a little higher and go a little faster.

This will allow you to spend some money, (new cassette, chain, rear derailleur) not just duplicate what you have that will make little to no difference.

John

You knew the answer before you asked the question. It's about watts produced, watts saved, and watts/kg when climbing. Watts produced is entirely on you, your bike fit, your nutrition, your physical and cardiovascular capacity, your recovery abilities, your general health and that day's particular reserves, etc. That's the watts produced side.

So, you're asking about watts saved. Yes, a perfectly clean and tuned, well lubricated top-shelf drivetrain can safe you a few watts, like a few.

Several posters mentioned smoother shifting, which is a real thing. One reason I prefer certain brands of crankset is that the shifting is noticeably better on the upshift. This equates the tiniest amount of energy saved. It is large enough to be measured, but not so large as to make a bit of difference to you or me.

On even a slight incline, gravity (does) and wind resistance (can) work against you. Lose as much weight from yourself as you can and still perform at your best. Have noticed that climbing while carrying a loaded backpack is harder than climbing when just riding around without the extra stuff?

I was thinking. Has the OP confirmed that his hubs are perfectly adjusted so as not to rob him of precious watts? Tires optimally chosen and at the best possible inflation? These things matter, too.

Their bike is 20 pounds lighter

I live in Colorado Springs, home to one of the Olympic Training Centers. so I get passed a lot , but not by "casual" cyclists. And not in the snow...probably because so few people ride in snow and ice. I ride with studded snow tires in the winter and passing cars going up an icy hill is supremely satisfying.

You clearly haven't pushed a Fiat 500 with a Ferrari transmission off a cliff!

My impression from the guys at the local dealership with a Fiat franchise is that they would be fine with extensive testing to determine the terminal velocity of a Fiat 500 when dropped from altitude. 😊

Otto

On the other hand, if you put a Ferrari engine into a Fiat 500 and made no other changes it still would not go 150 mph, since it would kill the transmission pretty much instantly as soon you'd really step on the pedal.

A Panasonic DX 2000 was my first proper road bike.

Thanks for the reply. After the new components, it is so much better. The hills were killing me. It has an old flywheel and I may see if I can upgrade to a 11-32 or 34 and do a cassette. Would take some research.

While I got you. I am in the Northeast USA and the roads SUCK. I have 700 x 23 and was looking for a bigger tire and lower pressure. If it fit I was looking at 32 and kind of make it a gravel type bike. I occasionally have some gravel roads.

I figured as much. I have some muscle mass and I know that takes oxygen. That being said, I think they have better cardio, stronger legs, and lighter everything. Fascinating though.

Word

Informative, thanks.

Thanks. I have a large cage derailer on now but have to look up the specs. I would have to buy new rims (I think) since my bike has a flywheel and not a cassette if I upgrade to the current century.

I hear you. I really thought it made VERY little difference but I am by no means an expert. It's a hell of a thing the different types of fitness there are. Some wiry frames can have insane cardio AND stronger legs over time. I was just curious about the math, I do it for the workout, not speed.

My shifters are on the frame and i have to read down. It blows. I will have to do research to even see if I can convert that. In due time.

Thanks for the reply.