After having ridden around with a lightened flywheel (done to Roger Ditchfield's specs) for a number of years now, I have decided to swap back to an OEM unit for a change/experiment. I swapped bikes with one Jack Flash last weekend and was really impressed with how smooth his engine was, so I'll see if this exchange narrows the (vibration) gap on my bike. My bike is ridiculously responsive (the product of the numerous rotating weight reductions carried out over the years, including the recent addition of carbon wheels and CMC front rotors) and I figure I can afford to step up to a heavier flywheel without losing too much of said response. As I ride my bike exclusively on the road and like to partake in decently long rides, the added smoothness may be a nice change. Of course, if it does't work out as expected, I can simply swap the lightened one back in.....

 

Sounds like a cool experiment. I think it's fun to remember how and why we upgrade, and whether the upgrades are really upgrades

James

 

Would be interesting to hear your experience with changing the flywheel back.

Speaking of weight, I'm curious, are you still running those Hyperplates? Was just reading about those and when I did a search, you of all people came up. Apparently, they aren't in business anymore, but it was a neat idea.

 

yep, still have the Hyperplates. Here is a quick list of other lighter rotating/reciprocating bits:
- lighter pistons and rods
- (slightly) lightened (and balanced) crank
- anti-rattle primary drive gear removed
- 520 chain and Al rear sprocket
- carbon wheels
- lightweight rear brake rotor
- CMC rotors (front wheel I know, but so long as the Wheel is on the ground it needs to be accelerated)

so there is a significant weight loss apart from the flywheel.........

 

so, get ye OEM flywheel on and the result is favourable (for me, anyhow). While these things are hard to quantify, vibration seems down by about 25% and low-rpm pickup is smoother and cleaner. Things are slightly less frantic response-wise but, as I mentioned earlier, all the other work done has given me a good cushion to work with. So, it works and will be staying in.

On another note, when I pulled in to the dealer to have this done (couldn't be bothered to do it myself, so I paid one hour of shop time), the tech goes out of his way to state that the chain (slightly loose, granted) is likely the source of my vibration (*yawn*, yeah, whatever). I explain what has been done to the engine and my reasons for going back to an OEM flywheel (sensing all the while this is going over said fellow's head). Seeing as how he is preoccupied with the chain tension, I tell him to tighten it while it's on the stand (throwing a bone to the dog, so to speak). I never thought to double check it afterwards, I mean the guy is a mechanic. I am riding along and keep hearing this mild "whirr" sound as I decelerate (never heard it before in 230,000 km of riding, never heard it on any bike btw). I pull over and check the chain tension: Jeezus!!!! You could likely use the chain as a spring board for diving!!!!! I got home and loosened it up (it wasn't so tight as to bend the shaft or kill the bearing, but quite snug it was). Moral of the story: check and double-check the work of shops. I am starting to think there aren't any good mechanics out there anymore........

 

Yah, more like tell them what not to do and get it all in writing... No reason to fiddle with another man's horse if he didn't ask ya to...

James

 

I thought adjusting the chain was a fool-proof undertaking.... guess I was wrong.....

 

Never underestimate Americans...

James

 

Canucks in this case.... but no difference in this instance.....

 

Never underestimate fools.

 

words to live by.....

the funny thing is, I am somewhat skeptical by nature and have difficulty trusting people (or rather their professionalism and ability to use their brains, or what little many seem to have). However, this puts me in a somewhat dark state and is something I struggle to change. Lo and behold, it seems that most times I try to give others the benefit of the doubt (such as this case; you'd think a bike mechanic would have something so rudimentary as setting chain tension down pat), I end up coming across a moron.....

 

Oh boy. Now I'll have him breathing down my neck next time I touch his bike. ;O)

 

First clue was that he barely listened to you because he was so infatuated with your chain tension....

When I used to take my bikes to the shop in San Diego I only spoke with the service manager. I refused to talk with anyone but him.... but then again he and I rode together on weekends


James