Chain Stretch

Nate--IRL--

Lately the chain on my bike has begun to "slip" when I try to accelerate hard in a higher gear. so I thought I'd better take a proper look at the Drivetrain.

To my amazement the chain is horrendously stretched, and it looks like I'll need to replace the front chain-ring also.

I'll be the first admit my bike doesn't get much love for all the hard work it does getting me to work every day, bar the odd drop of oil every now and again, but how to I avoid this in the future? I only do about 12k a day.

Also, If I were to get the repair done properly in a Bike shop, how much would I be looking at (north Dublin area)?

Nate

rab!dmonkey

As usual, Sheldon has all the answers.

The basic steps of drivetrain maintenance are

• Clean and lube your chain regularly (don't lube a dirty chain; there is a wrong way to apply lube too)
• Replace your chain when it is worn (you can use a special chain checker or a typical 30 cm rule)
• Replace your cassette after 2-3 chains, or one particularly worn chain (some cogs may wear more than others)
• Replace your chainrings after a chronically worn chain, or if they run noisily with a new chain

When you lube a your drive train, just put one drop on each roller (on the side which meshes with the cogs) of the chain - there is no need for lube anywhere else.

aFlabbyPanda

I paid 50€ for a new chain and rear cassette on my Trek just last month.

Nate--IRL--

I think I'll go for a new 48T crank and chain and do it myself, can't be that hard to do. Rear cassette looks ok, so i'll leave that for now. €50 sounds about right.

Nate

cdaly_

If your chain is that bad, your cassette is dead also.

Wishbone Ash

Nate--IRL-- wrote: »

.... the chain is horrendously stretched.....

Apologies for being pedantic but the chain doesn't actually stretch. The wear and tear on the rollers just creates extra 'give' on each link.

Why would you be considering a 48 with a triple?

...and clean your drive train. It's a holy show. Those chain rings should be sparkling!

Cee-Jay-Cee

Wishbone Ash wrote: »

Apologies for being pedantic but the chain doesn't actually stretch. The wear and tear on the rollers just creates extra 'give' on each link.

And the extra 'give' allows the chain to stretch more...

Darkglasses

Wash your chain once in a while, and don't put so much oil on. Excess oil allows the grit to cling to the chain, which accelerates the wear on rollers, chainrings and cassettes.

Brian?

Your drive chain is more dirt than metal! The horror.

tomasrojo

If you have mudguards, adding a front mudflap means that the chain gets much less schmutz thrown up into it from the road. If you had hub gears or single speed a chain case would be even better.

Not sure how easy it is to fit a chain case to a bike that wasn't manufactured to have them.

I had to make my own mudflap. It's not pretty.

Nate--IRL--

cdaly_ wrote: »

If your chain is that bad, your cassette is dead also.

Hmm ok, are all Shimano 7 speed cassettes compatible?

Wishbone Ash wrote: »

Why would you be considering a 48 with a triple?

...and clean your drive train. It's a holy show. Those chain rings should be sparkling!

I previously had a 42T but it was useless going fast or downhill - a noted grievance for many with the 2009 Subway 1.

Yes, I think I'll be looking after the drivetrain a bit more after the repairs

Nate

cdaly_

Nate--IRL-- wrote: »

Hmm ok, are all Shimano 7 speed cassettes compatible?

Probably. Is it a cassette or freewheel?

Keep_Her_Lit

tomasrojo wrote: »

If you have mudguards, adding a front mudflap means that the chain gets much less schmutz thrown up into it from the road.

My cycling vocabulary has just grown by one word!

I had to make my own mudflap. It's not pretty.

I know what you mean. But I'm sure you'll agree that the extra effort required to ensure that DIY parts aren't pretty is worthwhile. When the job is done, you can stand back with justifiable pride and admire their utilitarian fredishness.

Al Wright

From the photos it appears that you have a basic pressed steel triple chainset, usually 48/38/28 (or 26 teeth). The cost of one of those from your local bike shop could be up to Eur 30.-, on line CRC have them starting from Eur 15.-

More than likely the sprockets (on back wheel) are a freewheel block rather than a cassette, estimated cost Eur 15 to 20. (avoid the cheapest, I had trouble with a Sunrace brand)

Its essential to replace the chain also, a good quality basic Sram chain will cost less than Eur 20.- locally.

In general, on a basic commuter bike keep the drive train relatively clean and oiled. I found it to be economical to run the chain and freewheel to destruction, this permits me three chain/freewheel replacements to one chainset over approx. 11,000 miles (5 years).
However, on my 'leisure' bike on which the chainset alone costs more than a middling quality hybrid bike chain maintenance is thorough and chain stretch is closely monitored.

Nate--IRL--

Much appreciated, I'd already have the new Chainset and Chain on the way (~€40 delivered in total). I hadn't considered replacing the Freewheel (I'm assuming a freewheel until I have proper look tomorrow). I'll give it a good inspection and will replace if needed.

Probably a stupid question... but would a Shimano Freewheel be incompatible with SRAM shifters?

Nate

Al Wright

Yes, I think that freewheels are only available up to 8 speed and all brands have same spacing. You may need to adjust the rear derailleur to cater for clean gear changing on the new block.
Larger number of gears 9, 10, 11 speeds are available on cassette only. Here spacing differ, for example Shimano spacing are much tighter than Campagnolo at 10 speed.

Al Wright

Reading your question again;- there should be no compatibility problems

browsing

As @Al Wright pointed out, your back block is most likely a freewheel and not a cassette. If it is a cassette, you can just throw on a 8 speed one as they are the same spacing as a 7speed (assuming the rear freehub can accommodate!) I think it's nigh on impossible to find a 7 speed cassette on the main sites these days!

kumate_champ07

I remember reading somewhere that chain stretch was a myth. well its not, mine stretched so bad on my fixed gear commuter over 6+ months it became so loose it hopped off causing me to skid to a halt, there was no room in the dropouts to move the axle back so had to break off 2links.

they are very difficult to break with brute strength but over time they defintely stretch(unless its a Izumi 'super toughness', you could prob hang an elevator from 1 of them). I think Ill go for the kmc510 instead off the dirt cheap 410. I used to just adjust every month for the new stretch but a stronger chain is safer in the event of a freakish snap

rab!dmonkey

Chain stretch is a myth in the sense that the plates don't actually physically elongate due to the endured tension. Chains do indeed get longer over time, but it's due to the plates wearing notches into the pins, not any actual 'stretching'.

Lumen

rab!dmonkey wrote: »

Chain stretch is a myth in the sense that the plates don't actually physically elongate due to the endured tension. Chains do indeed get longer over time, but it's due to the plates wearing notches into the pins, not any actual 'stretching'.

It's not called "plate stretch" though.

To "stretch" generally means "to get longer". Most things which stretch do so by changing shape uniformly (at a macro level); a chain is just different in that we can see its structure.

So "chain stretch" isn't really a myth at all, it's just slightly misleading as to the underlying cause.

youtheman

rab!dmonkey wrote: »

Chain stretch is a myth in the sense that the plates don't actually physically elongate due to the endured tension. Chains do indeed get longer over time, but it's due to the plates wearing notches into the pins, not any actual 'stretching'.

Have to disagree with you there. When I buy a new (overlength) chain and I put it beside the old chain to try see how many links I need to remove then I am shocked by how much it actually stretches.

Nate--IRL--

Al Wright wrote: »

Reading your question again;- there should be no compatibility problems

Much obliged - thanks.

EDIT:- had a quick look and it seems it is a cassette - they are a bit cheaper too which is nice.

Nate

BadCharlie

Taking from sheldon

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 link pin 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 link pins by the inside edges of the bushings. With bushingless chains, the inside edge of the side plate hole that rubs against the link pin has a smooth radius instead of a sharp corner. This probably contributes to the greater durability of bushingless chains.

http://sheldonbrown.com/chains.html

rab!dmonkey

Exactly what I was getting at, Charlie.