Bicycle Mechanics - how many Kms. before change?

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View Full Version : how many Kms. before change?


closetbiker
08-24-04, 01:21 PM
I last changed my 7 speed cassette / chain about 10,000 kms ago. This is on a bike that only gets out in the sun and is cleaned and oiled regularily. I spin and don't grind out the gears below 90 rpm.

I mentioned this to my lbs and the owner was suprised as he said, he's finding his riders are changing them about every 5 or 6,000 kms.

I went home and checked the change before the last one and I changed it at about 10,000 kms. as well.

I'm not having any problems from exessive wear on the drive train and I'm thinking of waiting another 2 or 3,000 kms. before I change the set up.

How many Kms. does everyone here manage before changing the drive train? Am I odd for getting so much more milage before a change?


sydney
08-24-04, 01:26 PM
I last changed my 7 speed cassette / chain about 10,000 kms ago.

I mentioned this to my lbs and the owner was suprised as he said, he's finding his riders are changing them about every 5 or 6,000 kms.

I went home and checked the change before the last one and I changed it at about 10,000 kms. as well.

I'm not having any problems from exessive wear on the drive train and I'm thinking of waiting another 2 or 3,000 kms. before I change the set up.

How many Kms. does everyone here manage before changing the drive train? Am I odd for getting so much more milage before a change?
It's not about miles or km. Too many variables. Some riders get less than 1000 miles,and some get 10,000.It's about chain wear that can be measured. A 1/6" of stretch in a foot of chain and it's time to dump it.

Dusk
08-24-04, 01:44 PM
Check out the tread Chain Slip - New XT Cassette in the Maintenance area.


madpogue
08-24-04, 01:50 PM
A 1/6" of stretch in a foot of chain and it's time to dump it. Try 1/16" . 1/6 would be way past its bedtime. But the "not about the kms" bit is right-on.

sydney
08-24-04, 02:00 PM
Try 1/16" . 1/6 would be way past its bedtime. But the "not about the kms" bit is right-on. He He He, typo. Good catch.

closetbiker
08-24-04, 02:24 PM
Check out the tread Chain Slip - New XT Cassette in the Maintenance area.

I guess that's what I'm saying when I mentioned I'm not noticing any problems from exessive wear on the drive train.

I have no chain slip or skip and the drive train still feels good (no grinding).

Maybe I'll just keep on going untill I feel something (like grinding, slipping or excessive wear in certain cogs).

late
08-24-04, 02:40 PM
After several thousand miles, that chain doesn't owe you a thing.
Finish the season, and sometime between now and next spring, I'd get a new one. Cheap insurance.

Dusk
08-24-04, 02:46 PM
I guess that's what I'm saying when I mentioned I'm not noticing any problems from exessive wear on the drive train.

I have no chain slip or skip and the drive train still feels good (no grinding).

Maybe I'll just keep on going untill I feel something (like grinding, slipping or excessive wear in certain cogs).


I'm 150 lbs, ride 90 - 110 RPMs ,avg speed 17-19 mph. For a test I took a Lemond Zurich with Ultegra 6000 miles before the chain came out of spec on only 7 of 108 links. $38 for the new cassette, $20 for the chain. Never had any problem until about the last 200 miles and then only about 8 slip shifts. Under a scope the chain shows no wear to the bushingless ridges, the rollers only show mild wear and the side plates show wear but I can't measure it.

The down side of the test I may have shortened the chain ring life some.

Common chain logic I should be on my 4th chain and Third cassette. But I wasn't swaping wheels so no real damage problem. If I had keep to the common program it would be about $190.00.

Do what makes sense for you. Just keep in mind that you might replace the whole drive train if you push it out to the limit.


Cheers

Don Cook
08-24-04, 03:00 PM
On one bike in my garage there is 13,679 kms on the chainrings and the 9spd cassette. I have no intention of changing it anytime soon. My expectation is that with continued proper maintenance and proper shifting technique they will last another 13,000 kms.

sydney
08-24-04, 03:13 PM
I guess that's what I'm saying when I mentioned I'm not noticing any problems from exessive wear on the drive train.

I have no chain slip or skip and the drive train still feels good (no grinding).

Maybe I'll just keep on going untill I feel something (like grinding, slipping or excessive wear in certain cogs).
Better bet is to learn how to measure a chain.That way no guessing. Also if the chain gets worn enough to skip, it's likely trashed the casette. Replaced at the right time, a casette is good for many chains.

John E
08-24-04, 08:01 PM
As I mentioned in another thread, I recently had the new experience of losing a chain roller (without chain breakage), presumably through a process of seizure and gradual wear, unless it was cracked or otherwise preweakened at the factory. (Since the failure did NOT occur where I pushed in a rivet to assemble the chain in the first place, I cannot gracefully take the blame for a user-induced tight link.) This is the first time I have ever had to replace a chain before it reached the 1/2-percent elongation point mentioned above.

Fortunately, I have never broken a chain while riding. If I keep my chains properly lubricated and replace them often, I can get alot of use out of my cogs and chainrings.

Rowan
08-24-04, 08:52 PM
Several factors at play here, closetbiker. You are using a 7-speed transmission. The chain is naturally more robust than a 9-speed one. You regularly maintain the chain with cleaning and lube (and most likely keep everything well tuned). You avoid the conditions mostly likely to promote transmission wear. You use a high cadence reducing pressure on the transmission. Presumably you also make silky smooth gear changes.

The 5,000 to 6,000km wear-out rate for chains appears to be predominantly for the thinner 9-speed variety. You can bet less-than-ideal riding style and maintenance habits are contributing factors.

I have an 8-rear/double-front on one bike that has not been changed out since new... 10,500km ago. I'll probably get another 2 to 3 thousand out of it, if not more. Mind you, it has indexed downtube shifters, not STI.

The current transmission (9-sp rear, Deore triple front, Tiagra brifters, SRAM PC49 chain) on my touring/commute bike has been going for almost 6,000km and is showing signs of wear on the cluster and in the chain. The outer chainring is steel and has not been changed out since new, 25,000km ago. The middle and inner steel chainrings were changed out around 6,000km. I spend most of my time in the middle ring. This bike is ridden rain, hail or shine. It does have fenders and flaps. Chain skip is only just now starting to appear in one gear combination. I'll change everything out for my next big rides starting in late September, but will still get around 7,500km out of the current chain.

A friend got close to 20,000km out of his eight-speed rear/triple front set-up using up-market thumb shifters, and he regularly rides gravel roads (he lives at the top of a very steep one), and lubricates with WD40. He also has fenders. He has a VERY smooth riding style.

Of course YMMV.

closetbiker
08-24-04, 10:32 PM
My wet weather commuter's drive drain has to be changed at about 5 - 6,000 kms. because I start to feel problems. I thought I should be able to get twice the wear out of my pampered bike. I'll be giving it a go.

Thanks for everyones input. It's nice to be able to hear from so many that have knowledge and experience in this area.