Mar
13
2010

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Maintenance

by Tyler

Today, I replaced the chains on our bikes. According to bicycling community legend Sheldon Brown, you can gauge their level of wear by using a ruler. You're supposed to measure from the center of one rivet, to the center of one twelve links away. On a new chain, the distance should be exactly 12". A worn one is ready to be replaced when it measures somewhere between 12" 1/16 and 12" 1/8th.

Both of our chains measured just shy of 12" 1/8th. I should have replaced them a bit sooner. Tara's gears are fine, but my aggressive riding style has worn down the two smallest cogs on my rear cassette (the big cluster of gears in back) to the point where they don't mesh with the new chain. Instead, it skips right over several of the teeth (they worked with the old chain because they wore out into one another).

My crankset (the big gears up front) has been affected too. The center ring, where I spend 90% of my time riding, now exhibits a slight clicking as the teeth don't quite line up with the new chain. I think that will fix itself when it wears in a little bit though. For now, I'll just have to start varying the ratios I like across all of my available gears. Lesson learned: measure your chain regularly and use all available gearings to minimize wear on favorites.

I need to look up how bad it is to run a totally diagonal chain-line (biggest ring up front, biggest in back or conversely, small/small). If anyone out there has feedback on this, I'd love to hear it.

In other maintenance-related areas, we've been riding with only one spare tube since Tunisia. We also just ran out of chain lube. A visit to a bike shop was on order for today. At Miwa's recommendation, we headed over to a great place just a few blocks from their apartment. We were in for quite a pleasant surprise.

Several weeks ago, I ordered a boatload of spare brake pads which Tara's parents then shipped to us with our last supply package. Unfortunately, I ordered the wrong pads (ones for road bikes, not mountain bikes) so we had a pile of them to send home. When we arrived at the shop I was pleased to see that they had the same ones, and even more pleased when they were willing to buy ours from us!

It gets even better: I paid roughly $50 USD for 10 sets of pads, but the company I ordered them from sent us 11. The bike shop was willing to pay us €10 apiece for them. At current exchange rates, that is a net profit of $100 USD!

So, we went on a shopping spree and got some "free" maintenance done as well! In addition to brake pads, I had ordered a set of bottom bracket cups for both of our bikes (the part on our bikes that the crankset spins about). Again, Tara's were fine but my aggressive riding style (lots of hard pedaling out of the seat) had worn mine down to an early death.

I would have replaced them myself but it requires a heavy tool that has no other use beyond removing the cups. I had them replace both sets and we saved Tara's in case something unforeseen happens to either of our new ones.

While our bikes were being cared for, Tara found her new favorite piece of kit: riding gloves. I picked up enough chain lube to last us until we reach Southeast Asia, some degreaser, four spare tubes and a big new bell for Tara's bike to replace her old broken one. All for $50 or, about €36!

Eastern Europe, here we come!


Previous Gear Entry
Velocity Rims: Part 3
In Years Past and Future
2009 - Final Preparation
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3 comments

Hi Tyler,
Here is my "shift advice". I used to hate crossing my chain. This lead to overusing 1 or 2 of the cogs, just like it did for you.

The main principal to apply in order to minimize teeth and chain wear is that using bigger chainrings and cogs will cause less stress on the chain and teeth. Bigger rings and cogs have more leverage and more teeth so will last longer than small ones.

Crossing a chain is no problem as long as you stay away from the extremes. So avoid big-big and small-small. The best is to calculate the ratio between the different combinations of rings and cogs and you will see that once you go to the smaller cogs in the 2 smaller chainrings, there is another combination of bigger chainring and bigger cog that will give about the same ratio.

From your "gear" page I see that you have the same setup as I do on my touring bike (44-32-22 with 11-34). I use the 44 with all cogs except the 3 biggest ones. The middle chainring with all cogs minus the 3 smallest and the biggest. The smallest chainring with only the 4 biggest cogs.

Have a look at the ratios below and you will see how logic this is.

44,00 32,00 22,00
11 4,00 2,91 2,00
13 3,38 2,46 1,69
15 2,93 2,13 1,47
17 2,59 1,88 1,29
20 2,20 1,60 1,10
23 1,91 1,39 0,96
26 1,69 1,23 0,85
30 1,47 1,07 0,73
34 1,29 0,94 0,65

Let me know if you have any questions. Have fun and be safe,
Eric
Posted by Eric on March 19th, 2010 at 5:05 AM
Eric--

Thanks for all the info! In the past we've used our middle chainring with all cogs on our cassettes and then more or less exactly what you defined for the large/small ones.

It is really interesting to see the ratios all laid out. I thought about doing it, but in the end decided to go by feel. So far, so good! We'll see how things are looking in a few months :)

Thanks again!

Tyler
Posted by Tyler on March 25th, 2010 at 1:02 PM
It sure is always a good idea to go by feel. It's better to force a little on your equipment rather than on your knees. So sure, ride in the gear that feels just right in the first place.

I keep following your amazing trip with a lot of interest. Thanks for all the efforts you guys put up to post so often. Great job!

Be safe,
Eric
Posted by Eric on March 26th, 2010 at 3:34 AM
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