# Do you need plastic guard on cassette?



## cyyoung749

My bike fell on the ground and plastic guard on cassette got cracked apart. It didnt just competely came off but some of the parts came off and most of the parts are still hanging on cassette. Evertime I pedals plastic guard also moves and makes weird sound. Can I take this plastic guard off or Should I install a new plastic guard? Is it important to have plastic guard? Thank you


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## enzo24

The plastic guard serves an extremely important purpose!




To keep someone from suing the bike company. Same as the little tabs on your fork that prevent you from using a quick release, wheel reflectors that cause massive vibrations at any kind of speed, etc. There's already a device to prevent your chain from going into your spokes, it's called a limit screw.


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## tomk96

upgrade to a carbon fiber one.


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## triumph3banger

Just go with a solid rear wheel. The cool factor would be over the top...


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## rider9

The plastic disk is lovingly referred to as a "dork disk." It may be removed without harming you bike in the least.

I am more concerned about the rest of your bike. That had to be a pretty hard knock to break that disk.

Did you check the whole thing over? Wheels true? bolts/nuts tight? Lose anything important?


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## Samadhi

tomk96 said:


> upgrade to a carbon fiber one.


where do you find those? Link?


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## Opus51569

cyyoung749, you may hear it referred to around here as a "dork disk". The purpose of the guard is to keep the chain from over shifting into the spokes by accident. As enzo24 points out, though, as long as the derailleur is adjusted properly that kind of over shifting is very unlikely to happen.

Having said that, since your disk broke as a result of your bike falling over, you can remove it and don't need to replace it, but make sure your derailleur is still properly aligned.


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## Guest

tomk96 said:


> upgrade to a carbon fiber one.


I say paint it metallic gray and cut teeth into it, that way it will look like you have a 40-tooth bailout cog


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## Samadhi

I took the "pie pan" off my bike before it left the shop!! It was SO ugly. Twice as big as it needed to be.

I've heard that if you somehow bend the derailleur hanger it can cause the chain to flip off the big cog even if the limit screw is set properly


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## My Own Private Idaho

tomk96 said:


> upgrade to a carbon fiber one.


Like this one?

http://www.wmsracing.com/wmsweb/product11081.html


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## MXL

Yeah, my old Nishiki still has that huge thing on it. I have often considered removing, but I am trying to keep it original, even if it looks dorky. Speaking of dorky: I was riding with our group the other day and a new member showed up with a new Felt that was still wearing all the reflectors. Haven't seen that for a while.


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## Cyclin Dan

My Own Private Idaho said:


> Like this one?
> 
> http://www.wmsracing.com/wmsweb/product11081.html


Wow...


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## CBar

The bike fell and only the disk broke? How is that possible?


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## Juzzy004

Mandatory things to be removed from a bike before being seen in public are:
Bells
Wheel reflectors
LBS stickers
and YES - Spoke protectors...


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## MR_GRUMPY

The plastic guard serves an extremely important purpose!

It allows other riders to know who the noobs are.

That, and reflectors, and a two gallon seat bag.
.
.
.


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## Mike T.

Opus51569 said:


> The purpose of the guard is to keep the chain from over shifting into the spokes by accident.


Nope, it's to prevent the spokes being nicked by the chain if it ever derails over the top of the cogs. Only limit screws (properly set!) will do what you say.


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## teekster

Juzzy004 said:


> Mandatory things to be removed from a bike before being seen in public are:
> Bells
> Wheel reflectors
> LBS stickers
> and YES - Spoke protectors...


Add to that list the ridiculous amount of yellow warning stickers I found on my wife's new Specialized.


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## tlg

I think they're acceptable IF they are not larger than your biggest cog, and preferably clear. 
But when they look like this? WTF!


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## ddimick

My Own Private Idaho said:


> Like this one?
> 
> http://www.wmsracing.com/wmsweb/product11081.html


Oh my. "But then we have all dropped a chain between the spokes and cassette no matter how well tuned our bikes are..."

Do they make a version that has some ceramic bearings superglued on there somehow?


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## mpre53

tomk96 said:


> upgrade to a carbon fiber one.


All the cool kids are now running titanium.


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## danl1

Opus51569 said:


> cyyoung749, you may hear it referred to around here as a "dork disk". The purpose of the guard is to keep the chain from over shifting into the spokes by accident. As enzo24 points out, though, as long as the derailleur is adjusted properly that kind of over shifting is very unlikely to happen.
> 
> Having said that, since your disk broke as a result of your bike falling over, you can remove it and don't need to replace it, but make sure your derailleur is still properly aligned.


This is my concern: How did it break? Best guess would be the RD being slammed into it, suggesting that the hanger or RD could be bent. That'd make taking off the disc a guaranteed disaster, unless the other appropriate adjustments were made. 

Likely time for a trip to the shop.


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## iclypso

OP Send the bike back to Trek for a replacment.


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## mpre53

iclypso said:


> OP Send the bike back to Trek for a replacment.


Normally a safe assumption, but every so often it's a good idea to go into a profile and look at a noob's prior posts. :wink5:

You mean Giant.


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## PlatyPius

Juzzy004 said:


> Mandatory things to be removed from a bike before being seen in public are:
> Bells
> Wheel reflectors
> LBS stickers
> and YES - Spoke protectors...


Some bike shops use those LBS stickers to determine if you get free/discounted service or not....


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## Shinjukan

To the OP who asked whether the spoke protector disc is really needed, it depends on who you'd ask. From the viewpoint of the Feds, refer to this link I stumbled upon:

Recall

Be the judge.


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## Oxtox

just take the useless piece of crap off.

and the spoke reflectors and the kick stand if you have those...


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## FastRich

Dude! Get that thing replaced ASAP! If 5.0 catches you out riding with no spoke protector it's a hefty fine and they'll likley impound your bike.


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## erik1245

My Own Private Idaho said:


> Like this one?
> 
> WMS Carbon Fiber Spoke protector


But is it laterally stiff yet vertically compliant?


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## tlg

You could always do this. But use Carbon Fiber rope and be uber cool.


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## Allthatflash

tlg said:


> You could always do this. But use Carbon Fiber rope and be uber cool.


Hahahaha that ****ing halarious


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## El Guapo

Won't a carbon fiber spoke protector be prone to exploding when exposed to direct sunlight?


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## maximum15

After installing a friends cassette on a new wheel for him, he informed me that he wanted the plastic disc put on his bike. I had left it off. But I was more than happy to oblige after some modification.


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## mpre53

El Guapo said:


> Won't a carbon fiber spoke protector be prone to exploding when exposed to direct sunlight?


Only if it got wet first.


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## davelikestoplay

PlatyPius said:


> Some bike shops use those LBS stickers to determine if you get free/discounted service or not....



This. Free tune-ups!! Ka-ching!!


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## iclypso

maximum15 said:


> After installing a friends cassette on a new wheel for him, he informed me that he wanted the plastic disc put on his bike. I had left it off. But I was more than happy to oblige after some modification.


Tough love > no love


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## Trekkin2

lol, I must be a total noob! I had no idea there was such stigma associated with keeping the "dork disk" on or that it was even referred to as a dork disk, or what supposed purpose, aside from signaling dorkiness, that it was trying to serve.

Whew, that was a mouthful!

Okay, so got it on the dork disk, but what's so bad about the spoke reflectors? If you happen to get caught out at night, won't they serve some purpose, if you don't have a proper front and rear light?


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## Samadhi

Trekkin2 said:


> Okay, so got it on the dork disk, but what's so bad about the spoke reflectors? If you happen to get caught out at night, won't they serve some purpose, if you don't have a proper front and rear light?


They throw the wheel off-balance. As speed increases so will the effect and after a certain speed is reached could actually become deangerous.

Some folks, myself included think they ruin the overall appearance of the bike. My LBS could take the DorkDisc off for me, but by law couldn't touch the reflectors - front, back and wheels. First thing I did when I got the bike home take the reflectors off.

My lights do an adequate job. I don't ride in pitch dark. If I do, I have a reflective vest just for that purpose.

If you want to keep the reflectors, if you feel safer with them on the bike rather than off, then by all means keep them. Aesthetics is one thing but personal safety is another and that is something you are personally responsible for. Do what you think is right.


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## peterk

Its so the chain wont fall into the spokes; are you sure? Hmm, I thought it was to help with aerodynamics, especially the really large ones.


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## PlatyPius

peterk said:


> Its so the chain wont fall into the spokes; are you sure? Hmm, I thought it was to help with aerodynamics, especially the really large ones.


You're kidding, right?


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## psycleridr

My Own Private Idaho said:


> Like this one?
> 
> http://www.wmsracing.com/wmsweb/product11081.html


I can haz one?


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## snrose

was wondering this myself, thanks for clearing up


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## Shinjukan

Samadhi said:


> They throw the wheel off-balance. As speed increases so will the effect and after a certain speed is reached could actually become deangerous.


I don't think this is accurate. A small piece of round plastic is not enough to overcome the overall weight and structure of the wheel. It was meant for safety, in case the chain gets in between the spokes and the cassette.


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## erik1245

Shinjukan said:


> I don't think this is accurate. A small piece of round plastic is not enough to overcome the overall weight and structure of the wheel. It was meant for safety, in case the chain gets in between the spokes and the cassette.


No... Samadi is talking about spoke reflectors -- have you ever held one? They've got some heft. You're thinking about the dork disc, which, indeed, has nothing to do with the wheel's integrity.

They're still both equally Fredly, though.


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## bigzebra

tomk96 said:


> upgrade to a carbon fiber one.


Only $43 bucks!!!

Carbon Fiber Spoke Protector | eBay

ETA: Guess I should have read the whole thread first to see other obvious links to wonderful carbon fiber spoke protectors... :idea:


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## Shinjukan

erik1245 said:


> No... Samadi is talking about spoke reflectors -- have you ever held one? They've got some heft. You're thinking about the dork disc, which, indeed, has nothing to do with the wheel's integrity.
> 
> They're still both equally Fredly, though.


Yes, I did held those too on my hand. They're still plastic, and a piece of that barely registered anything on my wife's kitchen weighing scale. And even that won't even affect even a bit on the wheel's trueness.


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## Samadhi

Shinjukan said:


> Yes, I did held those too on my hand. They're still plastic, and a piece of that barely registered anything on my wife's kitchen weighing scale. And even that won't even affect even a bit on the wheel's trueness.


Put the bike up on a stand.

Give the wheel a good spin with the reflector attached to the spokes. (the spin you place on the wheel should be between 5/10mph)

Observe what happens.

Multiply the spin by 3, which should approximate the wheel speed on a decent decent.

Consider the inevitable outcome.

~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'm not saying you can't or shouldn't ride a bike with reflectors in the spokes, but it becomes damned uncomfortable and in the right circumstances, a wheel THAT out of balance becomes a liability. I've had road-rash gravel scrubbed out of my flesh by very unsympathetic nurses. The reflectors go. Anything that I think compromises my safety on the bike goes. I also think it's ugly as sin. Color me vain, but if I don't like how something looks and serves no useful purpose exclusively, it's gone. Your mileage may differ.

Ride on


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## Shinjukan

Samadhi said:


> Put the bike up on a stand.
> 
> Give the wheel a good spin with the reflector attached to the spokes. (the spin you place on the wheel should be between 5/10mph)
> 
> Observe what happens.
> 
> Multiply the spin by 3, which should approximate the wheel speed on a decent decent.
> 
> Consider the inevitable outcome.


Samadhi, I'm not trying to disagree with you just because I feel like doing it. I just have to state the correct facts. I've been doing that exercise you mentioned countless number of times, and I tell you first-hand, it doesn't affect the wheel's trueness at all. Not even a bit. Now, just to clarify, I'm talking about the plastic, cheap white-color reflectors that come with new bikes. So if what you're referring to is a reflector that can be used for fly fishing and weighs at least a hundred grams then I'll be the one to tell you: ditch that 'coz it has no place on your bike at all. :ihih:

Besides, the LBS will be the first ones who are going to raise a red flag if they find out that these reflectors and spoke discs affect the bike's performance even if these items are required by the Feds when selling new bikes.


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## mpre53

Reflectors are useless. The front one would only help if you were riding on the wrong side of the road. The rear one isn't as effective as a flashing tail light. When headlights pick up spoke reflctors, the car is either far away, or about to T-bone you. Either way, the reflectors are useless.


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## Shinjukan

Now that I have to agree with mpre. And since 99% of my rides are during daytime, those reflectors have no use for me as well.


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## tenkerman

Don't listen to anyone's advise regarding dork disks, saddle bags, etc. It really matters not what snap judgements other riders make about your gear. Get out and ride and enjoy yourself. Do it enough and you'll be able to pass a great many wanna-be racer boys that would otherwise mock you for having a saddle bag or a Trek with a bike shop sticker. Hey wait, my '07 Trek still has the dork disk, LBS sticker, and a saddle bag. Mods, can you change my username to "Fred" or "Freddy Faster Than You"?


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## Samadhi

Shinjukan said:


> Samadhi, I'm not trying to disagree with you just because I feel like doing it. I just have to state the correct facts. I've been doing that exercise you mentioned countless number of times, and I tell you first-hand, it doesn't affect the wheel's trueness at all.


I'm not talking about wheel true. I'm talking about wheel balance.

Two different things.




> Not even a bit.


I think you're wrong, but you're entitled to your opinion. Ride your bike anyway you want.




> Now, just to clarify, I'm talking about the plastic, cheap white-color reflectors that come with new bikes.


So am I. Those cheap, upgly, USELESS, POS'es that the law sez must be on every bike sold.



> Besides, the LBS will be the first ones who are going to raise a red flag if they find out that these reflectors and spoke discs affect the bike's performance even if these items are required by the Feds when selling new bikes.


By law (here in CO), the LBS can't remove the reflectors. They CAN, however remove the DorqDisq, but they'll only do that on request. When I got my current bike I asked the tech who was doing a pre-delivery inspect on the bike to do it for me because I didn't have the right tools at the time. They won't waste time removing stuff that comes OEM on the bike. Some people actually like those goofy things.


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## Shinjukan

Samadhi said:


> I'm not talking about wheel true. I'm talking about wheel balance.
> 
> Two different things.


Care to elaborate what's the difference between trueness and balance? I'm here to learn in this forum, in the most sincere form.


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## ddimick

If a wheel isn't true there will be movement of the rim from side to side when viewing the profile of the wheel; looking at it from the edge. This is solved by adjusting spoke tension to pull the rim into true.

Balance is if part of the wheel is heavier than other parts of the wheel. It causes the wheel to look or feel like it's oscillating when viewed from the side. The effect becomes worse as the wheel spins faster; you might never notice the imbalance from a wheel reflector at 20mph, but probably will at 50mph. As suggested above, put your bike into a stand and spin up a wheel. You'll probably notice that the bike is moving up and down in the stand; this is caused by wheel imbalance.

There is always some level of imbalance just from the weight of things like where the rim is joined. Some manufacturers (i.e. Fulcrum) make the section of the rim opposite the joint slightly heavier to compensate.

Fulcrum Dynamic Balance

In cars they solve for balance by crimping lead weights onto the rim.


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## Shinjukan

ddimick said:


> If a wheel isn't true there will be movement of the rim from side to side when viewing the profile of the wheel; looking at it from the edge. This is solved by adjusting spoke tension to pull the rim into true.
> 
> Balance is if part of the wheel is heavier than other parts of the wheel. It causes the wheel to look or feel like it's oscillating when viewed from the side. The effect becomes worse as the wheel spins faster; you might never notice the imbalance from a wheel reflector at 20mph, but probably will at 50mph. As suggested above, put your bike into a stand and spin up a wheel. You'll probably notice that the bike is moving up and down in the stand; this is caused by wheel imbalance.
> 
> There is always some level of imbalance just from the weight of things like where the rim is joined. Some manufacturers (i.e. Fulcrum) make the section of the rim opposite the joint slightly heavier to compensate.
> 
> Fulcrum Dynamic Balance
> 
> In cars they solve for balance by crimping lead weights onto the rim.


ddmick, could it be that the up and down of the wheel you're referring to is called "roundness" or "dishing" and not balance? Let's be realistic: very few could reach speeds of 50mph on a bicycle and try to notice if there's shimmy on their wheels. That's outright dangerous and pure s7up1d granting that one's a pro and able to reach that speed. If your bike wheels are not true, you'll start to notice it right before you reach 10mph because it's rubbing on your brakes, or if it's out-of-round then you'll feel the thump-thump on your bike even on speeds as low as 12mph if you're that sensitive to your bike. Now if we consider that the wheel is reasonably true and properly dished, and yet it still favors one section by always resting there no matter how one tries to freely rotate it, then perhaps there's something wrong with the wheel material when it was made, hence it's a manufacturing defect. In this case, it's still not the cause of that lightweight reflector. Plain impossible.

So I'm still not convinced that a 10-gram reflector could cause the wheel to become out of round.


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## ddimick

Yes, out of balance would have similar symptoms as a wheel that's out of round. A bicycle wheel can never be perfectly balanced because it will always have some weight variation at the rim. At the seam for a metal wheel, or the stem on a carbon wheel, etc. Put your bike on a stand and rotate the wheel. You'll find that it always settles in about the same place. Adding unnecessary weights to the wheel can only add to the inherent imbalance. At low speeds it probably won't matter. At high speeds it probably will.

50MPH is certainly not unobtainable or unheard of by recreational riders. I try to keep things below 45MPH on descents but every once in a while I break through 50. I want my wheels balanced as close to perfect as possible at those speeds.

Dishing is a completely different issue.


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## Shinjukan

ddimick said:


> Yes, out of balance would have similar symptoms as a wheel that's out of round. A bicycle wheel can never be perfectly balanced because it will always have some weight variation at the rim. At the seam for a metal wheel, or the stem on a carbon wheel, etc. Put your bike on a stand and rotate the wheel. You'll find that it always settles in about the same place. Adding unnecessary weights to the wheel can only add to the inherent imbalance. At low speeds it probably won't matter. At high speeds it probably will.
> 
> 50MPH is certainly not unobtainable or unheard of by recreational riders. I try to keep things below 45MPH on descents but every once in a while I break through 50. I want my wheels balanced as close to perfect as possible at those speeds.
> 
> Dishing is a completely different issue.


But we're talking about a 10 gram piece of plastic. How is that supposed to affect a wheel's balance, even at your so-called claim of 50mph? Even if you and Samadhi were claiming that it will exponentiate as the speeds go up, it still won't come to a point that it will affect the wheel's behavior at high speeds.

I didn't say 50mph is not attainable. What I'm saying is an overwhelming majority of recreational riders can't and don't want to reach that speed. You have always stated "probably". That means you're also not sure that those reflectors do contribute to the wheel's balance and handling and there's no scientific data to support that. Maybe you're an exception because probably you used to (or perhaps still) ride for a certain sponsor and your skills can handle such insane speed. But a majority of us can't. I only have 1 life so I try to save it as much as possible. So going back to that wheel topic, if a wheel imbalance can't be felt at 20mph like you previously stated, I'm fine with it. There is never a perfect wheel that's out there anyway.

Again, I'm not trying to discredit anyone here. I'm just after the correct and supported facts because I like to learn and absorb those that I don't know, but will also point out those that seem to be trivial for the benefit of others who are also trying to inform themselves through this forum.


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## peterk

PlatyPius said:


> You're kidding, right?


Maybe


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## Oxtox

Shinjukan said:


> But we're talking about a 10 gram piece of plastic.


do you have reflectors on your wheels?


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## ddimick

Shinjukan said:


> But we're talking about a 10 gram piece of plastic. How is that supposed to affect a wheel's balance, even at your so-called claim of 50mph? Even if you and Samadhi were claiming that it will exponentiate as the speeds go up, it still won't come to a point that it will affect the wheel's behavior at high speeds.
> 
> I didn't say 50mph is not attainable. What I'm saying is an overwhelming majority of recreational riders can't and don't want to reach that speed. You have always stated "probably". That means you're also not sure that those reflectors definitely contribute to the wheel's balance and handling. Maybe you're an exception because probably you used to (or perhaps still) ride for a certain sponsor and your skills can handle such insane speed. But a majority of us can't. I only have 1 life so I try to save it as much as possible. So going back to that wheel topic, if a wheel imbalance can't be felt at 20mph like you previously stated, I'm fine with it. There is never a perfect wheel that's out there anyway.


Whelp, neither one of us can prove our positions so we'll have to leave it at that. For obvious reasons, I'm as unwilling to test your theory at high speeds as you are. I'm no pro rider, just your average middle-aged guy who likes fast descents.

Bike Ride Profile | 30miles near Rancho Palos Verdes | Times and Records | Strava


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## WaynefromOrlando

MXL said:


> Yeah, my old Nishiki still has that huge thing on it. I have often considered removing, but I am trying to keep it original, even if it looks dorky. Speaking of dorky: I was riding with our group the other day and a new member showed up with a new Felt that was still wearing all the reflectors. Haven't seen that for a while.


Funny, I am restoring my old Nishiki Royal 15 too and I am trying to keep it as close to original too. I will probably not keep the dork disk though, but I would like to keep the dealer sticker from La Mesa Cyclery in La Mesa, CA and the base sticker from 32nd St Naval Station because they actually mean something to me. I liked that bike shop and it is now a carpet sales place and I haven't been in the Navy since 1995. I'll keep it a triple crank too because I intend to load it up with panniers and use if for my long distance riding and commuting once it is finished.

I won't keep the wheel reflectors though, I have been north of 50 mph on my old Nishiki and I could definitely tell there were reflectors on the spokes back when that bike was brand new. I took them off at the bottom of the Cuyamaca grade in SD near the stadium because the made the bike squirrelly at that speed. Without them, I managed to get a speeding ticket for going more than 60 mph down that same hill about a month after I bought the bike. Ya gotta love CroMoly steel, that bike was as stable as a Ferrarri at that speed!


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## nightfend

"But then we have all dropped a chain between the spokes and cassette no matter how well tuned our bikes are..."

No. Just no. That won't happen if you have any mechanical knowledge at all.


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## Shinjukan

nightfend said:


> No. Just no. That won't happen if you have any mechanical knowledge at all.


True. Those limit screws won't be included on the bike if it doesn't do its purpose. This is granting that the rear wheel is properly seated in the dropout.


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