Search found 9 matches

by Dan
4 Jun 2012, 7:26am
Forum: Bikes & Bits – Technical section
Topic: My aluminium front fork steerer {carbon forks} snapped off.
Replies: 147
Views: 28560

Re: My aluminium front fork steerer {carbon forks} snapped o

I heard the Eurosport commentator on the Paris Roubaix this year say that most of the bikes would not be used again after that one race!
by Dan
15 Jan 2012, 4:29pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear
Replies: 92
Views: 110410

Re: Chain wear

Since my last post my replacement KMC 10 Speed chain (X10.93, £15 at Merlin) has done 1830kms and my indexing has started to deteriorate. Taken the chain off and it has stretched 3.5mm against a new chain. This chain has been cleaned every 200km and dry lubed. Indexing now appears fine. So it is not just wear on the sprockets that is a limiting factor but indexing too, echoing Meic's point. Pity because I had been planning to recycle my stretched chains, but wont be doing this if the indexing suffers.
So I am going to accept that this is part of the price for having 10s Campag ergopower, and riding it in all weathers.

My other bike is a Thorn with a Rohloff. I don't put anything like to same milage in, but £10 1/8 track chains seem to last for ever - and are serviceable, it is a pleasure to use a chain tool on non-peened rivets, which slide in and out without tearing the peening and outer plates.

Trigger I have done as you suggested and changed my 50/34 compact for a standard 53/39.
by Dan
9 Oct 2011, 3:04pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear
Replies: 92
Views: 110410

Re: Chain wear

Since my June posting that my Campag Centaur 10s chain had stretched 5mm over its 1370mm length (0.36%), and had worn out my 11 tooth sprocket (such that a new KMC chain skipped on it) I put on a new KMC chain (£20) and Centaur block (£60).

After 3 months and approximately 1,200km of road club riding, with regular cleaning and lubrication, I took it off today and it has stretched 3mm over its 1370mm length, that is 0.22%.

Chris your points about the inaccuracy of the Rohloff chain checker, due to "roller play" leading to overestimated wear, and 11t sprockets wearing more quickly are taken.

Mick F, you write
I use two Campag chains and swap them over every 1,000miles or so. Both chains have done over 4,000miles so far with zero stretch on either of them. I expect to get a further 4,000miles yet but I may change them before that.
How do you measure the stretch?

So what to do?
Do I bin my old KMC chain (given that it has stretched 3mm (0.22%) and my previous chain had worn out my 11t sprocket by the time that it reached 5mm (0.36%) stretch), and keep running new chains for 1,200-1500km each? And see how many chains the cassette survives.
Or do I run a couple more new chains for 1,200-1500km each and then rotate the old stretched ones? Before replacing the lot, with the aim of using three chains to one cassette.
by Dan
11 Jun 2011, 3:00pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear
Replies: 92
Views: 110410

Re: Chain wear

Niggle, you are (nearly) correct, the Rohloff Caliber 2 measures stretch at 0.075 and 0.1 mm PER LINK (according to the instructions), not 0.075% and 0.1% as I mistakenly thought. So I was out by a factor of 1/25.4=0.039

Taking 1 link to be 1 inch (25.4mm) of chain the Rohloff chain checker calibrations of 0.75mm and 0.1mm per link translate to 0.075/25.4x100=0.30% and 0.1/25.4x100=0.39%.

Direct measurement of my old centaur chain against the new KMC showed it had stretched by 5mm over the length of the whole chain. This gives 5/1370mm = 0.36%.

Interesting that this is less than the 0.39 according to the chain checker. Presumably 0.36% is the true figure (unless older chains are more elastic and have to be measured under tension) and the chain checker produces a reading of 0.39% because increased play in the rollers exaggerates the stretch, as Niggle pointed out in an earlier post.

Anyway the chain has stretched enough to have worn my 11 tooth sprocket badly enough that a new chain jumps on it.

Regarding damage to the peening on rivets, here is a link to a bad tempered argument about it http://archive.roadbikereview.com/00/0EFBB3ED.php

And here is a link to some nice pictures on the park tools website showing damage to the peening http://www.parktool.com/blog/repair-help/chain-installation-derailleur-bikes the rivets that I extracted from my campag chain both looked like the images taken in the optical comparator. http://www.parktool.com/uploads/images/blog/repair_help/chain13.jpg
by Dan
9 Jun 2011, 12:28pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear
Replies: 92
Views: 110410

Re: Chain wear

I took off my centaur chain and put on a new KMC chain, sadly it skipped on the 11 tooth sprocket under full power. So the centaur is back on this time with a KMC missing link.

When I measured the old centaur chain against the new KMC it had stretched by 5mm over the length of the whole chain. This gives 5/1370mm = 0.36%, well over the 0.1% recommended for replacement.

I am surprised that it went from <0.075%, (using my Rohloff caliber 2 go-no-go chain checker) to this after about 2000km despite cleaning and lubing it weekly and using mudguards through winter.

My next question is should I carry on riding it until it wears out completely, or replace chain and cassette now to protect the chainrings?

On the point about reusing rivets. I took care when using a chain tool to remove the rivets, when I checked the ends of the rivets that I had removed (to remove the chain and fit a KMC missing link) they were seriously damaged, the peened end of one rivet was pulled off entirely, the other had been effaced. There was also some visible distortion of the outer plate around the hole.

Mick F you write
it's perfectly OK to break and re-join Campag chains. Yes, I know the pins are specially shaped and you damage them slightly, but if you're careful to get them back exactly correctly, the chain will have no ill effects.
how did you remove and replace them without causing this damage?
by Dan
4 Jun 2011, 11:11pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear
Replies: 92
Views: 110410

Re: Chain wear

If you are rotating campag chains do you use "missing links" or campag rivets each time?
by Dan
4 Jun 2011, 11:09pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear
Replies: 92
Views: 110410

Re: Chain wear

How many miles has your Campag chain done?


Hard to say exactly, very light use until this year, probably <<1000km and no significant stretch [<0.075%]. Then this year 2000km, and now >0.1% stretch.
by Dan
1 Jun 2011, 11:18pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear
Replies: 92
Views: 110410

Re: Chain wear

I ride a Campagnolo Centaur 10 speed groupset. I regularly check (maybe not enough) my chain with a Rohloff caliber 2 chain checker, and due to a sudden surge in my milage (I recently joined a racing club) the wear has jumped from <0.075% to >0.1%. I have been to two bike shops and both of then have said that Campagnolo chains are now so hard wearing that they advise riding the chain until it starts skipping and then replace both chain and cassette at the same time.

Is this a widely held view thesedays? Or at >0.1% wear is it already too late to run a new chain on the block (there are no/minimal visible signs of wear on the sprockets).

My preference is to replace the chain in the hope of extending the life of the cassette and chainrings.
by Dan
29 May 2011, 4:02pm
Forum: Bikes & Bits – Technical section
Topic: 23mm vs 25mm tyres, can you really tell the differance?
Replies: 121
Views: 8823

Re: 23mm vs 25mm tyres, can you really tell the differance?

Fascinating thread.

I bought a 25mm tyre, previously I was on 23mm conti GP 4 seasons front and back running at 100/105psi, now 23mm front, 25 mm back both running at 100psi.

On club runs the bike is less skittish and I am descending and cornering at greater speed.

I don't feel any need to put a 25 on the front as that handles well. I doubt that I will go back to 23 on the back as the back now feels clearly more stable on the road.