Beer Drinker Appreciation Society - Open For Business (Page 64)

It is always interesting to see the other side of people...my kids were via ICSI!

I personally ride an ISM Adamo Prologue; for me, fiddling with saddles was a necessity due to major numbness issues that were ruining my wife and I's intimate time, and going to my Adamo fixed that.  When I was having issues, I searched a bunch of forums (here, Slowtwitch, Weight Weenies, etc) to find similar problems and what solutions others have found, and went from there.

Questions: Last spring I had my bike tuned up. First ride after the tune up, I broke a spoke (first time ever breaking a spoke). Had it fixed. Then, all summer I had issues with spokes. I broke four last summer in total, at least three of them were on turns (all four maybe, but I can confidently say three of them were). I talked to the guy at the LBS yesterday about this issue and whether given my weight (300+) I should consider new wheels designed for heavier folks. He said that weight isn't usually the cause of broken spokes, but instead the pressure put on the spokes by the gears (and the lack of pressure on the other side).

He is technically correct. The torque applied to the hub by turning the crank is the biggest force acting on the spokes. Spokes, being an alloy material (typically) have a certain lifespan before they will fatigue. Every rotation of the wheel applies a force to each spoke. The number of times this force can be applied is limited and eventually the spoke will fatigue to point of break. Greater forces will reduce the time to fatigue. Unless you are a track sprinter and pushing out huge wattages, I doubt that this is causing your spokes to break. (sidebar: I ride the track with a young guy who weighs around 250lbs. He pushes out almost 1700watts in a track sprint. I've seen bicycle frames literally fold under the weight and force he applies to them. He's demolished 3 frames in the past 8 months but I've never seen him destroy a wheel) It is possible, however, if you had one faulty spoke that broke it was replaced incorrectly without properly tensioning the rest of the spokes around it, it could cause undue stress on a handful of other spoke and they will break faster. Weight of the rider certainly does play a role if this is the case. Chances are a combination of the two is happening in this case, one thing accentuating the already present problem. 

He also said that the spokes put on wheels by the manufactures are generally poor quality and suggested that I have the entire wheel re-spoked.

This is true, once again, to a certain degree. All stock wheels are generally of poor quality but not so much that they ought to fail as often or as catastrophically as you describe. The quality (or lack thereof) of the wheel could be accentuated by weight of the rider. Most wheel manufacturers offer two classes of wheels. Standard and Clydesdale. You might be better off getting a Clydesdale set. I recommend Flo Cycling. They make a great set of 30mm wheels that are pretty inexpensive but built like a brick sh*t house. They use top quality spokes and the rims are high grade aluminum. It's run by a couple of Canadians out of Michigan and they're great to deal with (they specialize in affordable aerodynamic triathlon wheels. I have a set of 60/90s they're absolutely amazing). 

So, that is what I am doing. Any thoughts on the causes of broken spokes and/or whether this guy is just blowing smoke up my...? I generally like this shop, but not this particular guy at the shop. I've never felt that they were dishonest with me or anything like that, I just don't know enough. Also, is changing a spoke something I should be able to do myself? I saw it in the bike maintenance book I bought, but it looks quite complicated and seems to require several specialized tools. Thanks!

Changing a spoke is definitely something you can do yourself but it does take some time and patience to do it right. It's not the actual changing that is difficult. It's getting the spoke tensioned correctly in relation to the other spokes. Over tightening one spoke will cause the spoke on the opposite side of the rim to slacken. This results in the overtightened spoke taking all the torque rather than it being shared by both spokes. There is always going to a variation in load, since tightening all spokes to the same tension might not mean the wheel is true. You have to tighten and loosen spokes to get the wheel straight because of natural imperfections in the rim shape but they should be pretty evenly matched.