Drivetrain weight savings - are they worth it?

Bhima

Anyone had experience of lightweight drivetrains and thier impact on performance?

Some weight changes will be more effective than others. This is obvious. What about the drivetrain components though? I've heard all the arguments about wheels but, after a long discussion with a physics lecturer, I now understand that "rotational weight" is not so different to normal weight.

I'm not someone who moans that my bike is too heavy but I've been thinking more about the drivetrain recently - when you put energy into making the bike go forward, it's going straight to the drivetrain. If you think about it, when you push and pull the pedals, a 1g difference in the weight of a crankarm could make a massive difference over an hour of spinning. :shock: If the difference is substantial, it means you could push a higher gear slightly easier... That's how i'd imagine it, anyway.

However, If you turn the bike upside down, and spin the cranks round backwards (so the weight of the wheel is irrelevant), it doesn't feel like your putting much force into it so i'm unsure about how much of a difference would be felt if all the components were half the weight... When I took off my chain, I noticed how easily the cranks spinned round too. I'm not too sure if 100g off them would make that much of a difference... :? So it made me realise how much friction the chain was causing! :!:

The lightest chain I can find is 240g and the "standard" chains I get down the local bike shop for £15 are 280g so there's not much scope for a big difference there. Would the 40g loss make much of a difference when spinning the cranks backwards?

Rear and front mechs weight seem to only matter when shifting and their smoothness (from good maintainance) is probably more important.

In another thread 2 weeks ago, I think we established that low-friction bottom brackets were not worth the money.

So i'm guessing that lighter Chainrings, Cassette, Pedals and Crankarms would be a better way of getting your power down more effectively...

How much of a difference is there to be had?

keef66

I suspect once you get into 105 or Veloce territory, further weight savings become very expensive and the benefit is 98% psychological.

If you look at pro bike developments most advances are in aerodynamics of bike and rider, although the UCI weight restrictions may have something to do with that.

dilemna

Not sure what components you have but the law of diminishing returns applies. To lose further small amounts in drive chain weight will cost ££££. Better to have a clean and well lubed drivetrain. I would say a Dura-Ace chain or decent chain well lubed makes one hell of a difference as of course does a well maintained drive chain. I would concentrate on this first before shelling out ££££s. Better to improve fitness and develope a really good set of legs.

Bhima

Yes, fitness is my priority first! You only notice the better equipment at levels of high-intensity riding so i'm trying to hit a brick-wall with my firness before I reach for the wallet...

So I guess, like with most bike stuff, the mid-price stuff is probably best then? Just looking at some rear mechs which are £300+ and only save 10g on the mid-range stuff... :? It's just silly! :shock:

markos1963

I would say if you have 105 or Veloce kit on the bike and its well maintained then leave as is. The cost involved in getting a worthwhile weight loss is not cost effective. The £5-600 to upgrade a groupset would be better spent on lightweight wheels and tyres.