Bike Anti-Porn - When Things Go Wrong

these:

http://www.pedalroom.com/member/DirtyBobbysBikes

christ

his ralaigh macaframa is nice, the rest are shocking.

Ferrari are letting their brand go right down hill, compared with the old Colnago/Ferrari collaborations. Google SPOEX 2012 for loads more anti from the Seoul sporting goods trade fair

I would.

When I think about it a little more it does seem like a bit much to ask. Say you produce 600w over 15sec from traffic lights. Chain length is about 70 links but only 40 of those would be under stress. That's a fairly spread out stress. Link plates are about 1.2-1.5mm thick I think so 15w isn't going to do much damage.

I'm sorry to be a bit anal here but this isn't true. Every link has to take up all the energy. The first chainlink takes all the energy and transfers it down to the next link and so on.
Stating the stress in Watts doesn't make much sence either as energy is Torque over time. Torque is the figure you want.
Track sprinters can very momentarily make upwards of 700Nm of torque. With a 48t chainring that is the equivelant of hanging a 735kg block from it.

Mechanical_vandal speaks the truth so far, in my oppinion.

EDIT: Isn't edscoble a bike mechanic?

^all of the above, and kids with 23t chainrings on their micro-drive toy bikes put over twice as much tension into the chain for a given amount of torque.

I'd still like to see actual measurements showing plastic deformation of the cranked side plates of a half-link.

EDIT: Isn't edscoble a bike mechanic?

Supposedly, which is why his comment about non elongation of worn chains worried me.

Well technically what he said was right, so...

Well technically what he said was right, so...

He said "chains definitely don't stretch" which is false.

They do stretch, and thats the main reason the need to be changed from time to time.

Looking at this picture you can clearly see the elongation of an old chain vs. a new one.

The difference is not huge and comparing only a few links might let you think they are equally long, but measuring a 100 links or so and the difference is about 1/2" when a chain is worn out.

sorry, but ed was right, as stretch and elongation are 2 different things and here's sheldon's view....

Chain "Stretch"
Cyclists often speak of chain "stretch", as if the side plates of an old chain were pulled out of shape by the repeated stresses of pedaling. This is not actually how chains elongate. The major cause of chain "stretch" is wearing away of the metal where the rivet rotates inside of the bushing (or the "bushing" part of the inside plate) as the chain links flex and straighten as the chain goes onto and off of the sprockets. If you take apart an old, worn-out chain, you can easily see the little notches worn into the sides of the rivets by the inside edges of the bushings. With bushingless chains, the inside edge of the side plate hole that rubs against the rivet has a smooth radius instead of a sharp corner. This probably contributes to the greater durability of bushingless chains.

^^

Yeah, sorry but that's not stretch.
That's kind of what this whole tedious pedantic discussion has been about, and i'm sorry to perpetuate it.

I'll be in the garage hanging myself then.

Glad everyone is on the same page and we got the terms cleared.

Interesting discussion...

Taking advice of edscoble is about as rewarding and worthwhile as drinking a pint of horses piss

#81 onwards for LFGSS Comedy Bellend Gold

http://www.lfgss.com/thread9354-2.html

why be a prick about it though? At some point every single person here knew fuck all about bikes ...

I'll be in the garage hanging myself then.

Careful not to stretch the chain.... oh no, I mean wear the chain...

Or do I?

why be a prick about it though? At some point every single person here knew fuck all about bikes ...

Yeah, when they were 6

Taking advice of edscoble is about as rewarding and worthwhile as drinking a pint of horses piss

#81 onwards for LFGSS Comedy Bellend Gold

http://www.lfgss.com/thread9354-2.html

This is classy, can i rep the whole thread please?

'Classy' doesn't enter into it.

IMO Ed had it right about wear being different to stretch but he said he had compared new and old chains and had not seen any elongation and, as has been subsequently demonstrated, elongation should be clearly visible in a worn chain.

Every link has to take up all the energy.

Really? Even the ones on the bottom on their way from the chainring to the sprocket, the ones which go slack when under acceleration?

I speak in watts because that is all I know from doing power tests.

I speak in watts because that is all I know from doing power tests.

But power is largely irrelevant to the question. For illustration, calculate the chain tension in the following conditions, all at 500W transmitted power and ½" chain pitch:

Crank speed 60rpm, chainring size 26t (Street BMX)
Crank speed 120rpm, chainring size 52t (track pursuit)

The BMX rider is applying 4 times as much chain tension, even though the total power transmitted is unchanged.

The tension is not shared among the links, every unsupported link under tension has to take the full load. The load drops off rapidly as the chain wraps around the chainring or sprocket, dropping to zero (assuming no preload or gravity) as the chain leaves the chainring/arrives at the sprocket.