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-   -   Have you ever been burnt by a hot chainring? (http://www.bikeforums.net/general-cycling-discussion/255123-have-you-ever-been-burnt-hot-chainring.html)

mike 12-22-06 10:11 PM

Have you ever been burnt by a hot chainring?
 
I was going on a tour awhile back and had an unusual experience. It was a HOT day - over 100 F mercury. The heat was glaring off the road.

We were riding pretty hard which may have had something to do with it, but when we stopped for a break, my calf touched my chainring. The chainring was HOT and it burned my calf to the point that I got a perfect chainring blister burn.

It looked cool after the blister popped and it turned into a red-brown chainring scab.

I thought this was very unusual. Has it happened to anybody else or have you heard of it?

ax0n 12-22-06 10:40 PM

It's not unusual for any type of metal to be hot enough to cause a burn if it's out in the sun. Usually, air moving past it should keep temperatures down a bit, but the road surface itself can get to 130, 140+ degrees. Metal, especially painted or anodized dark colors, can get even hotter, and metal transfers heat very quickly.

I haven't been burned by a chainring, but I've been burned by the hood of a car in the Kansas sun, and it doesn't even get that hot around here.

JanMM 12-23-06 10:28 AM

If water at 120+ degrees can cause a scalding, then it would seem that skin is at risk for burn injury by contact with anything at a higher temperature.

eubi 12-23-06 03:58 PM

Can't say that I have.

It gets hot in the summer here too. Sometimes, I have to keep my tools in a bucket of water to keep them cool. I usually can't work past 11:00AM in the summer anyway.

mike 12-23-06 05:04 PM

Quote:

Originally Posted by eubi
Can't say that I have.

It gets hot in the summer here too. Sometimes, I have to keep my tools in a bucket of water to keep them cool. I usually can't work past 11:00AM in the summer anyway.

Wow, I can't even imagine that; Keeping tools in a bucket of water to keep them cool. Holy smokes! What kind of electric drill do you use?:D

Seriously, that is just incredible. Thanks for sharing that kind of lifestyle experience. Southern California is it? Boy, "Some Like It Hot"

eubi 12-25-06 10:21 AM

Quote:

Originally Posted by mike
Wow, I can't even imagine that; Keeping tools in a bucket of water to keep them cool. Holy smokes! What kind of electric drill do you use?:D

Seriously, that is just incredible. Thanks for sharing that kind of lifestyle experience. Southern California is it? Boy, "Some Like It Hot"

Hahaha. Got me on that one! I keep the power tools in a propane powered refrigerator :D

Hope the burn heals quickly...but I bet it looks cooool!

kf5nd 12-25-06 12:03 PM

I got a burn from metal tools lying out in the sun when it was 104 F in the middle of the summer once. Never again!

hotbike 12-26-06 04:34 PM

That chainring may have been a lot hotter than 100 deg.

You have to take into account the heat generated by FRICTION.

From your description, you didn't have enough oil on the chain.

If you had more oil on the chain, you would have seen a black, greasy mark on your calf, not the red blister you described.

Riding hard definitely had something to do with the temperature of the chainring. Without oil, metal on metal friction can create lots of heat.

Eatadonut 12-26-06 04:54 PM

I'm gonna disagree with hotbike - I doubt there's all that much friction between chainring and chain, or you'd be dying from the squeaking.

But I've ridden several summers in Texas, and the sun will turn your bike into a weapon. I burned my ankle at a stoplight once when I unclipped and let my leg rest against the crank.

eubi 12-27-06 06:50 AM

Quote:

Originally Posted by hotbike

Riding hard definitely had something to do with the temperature of the chainring. Without oil, metal on metal friction can create lots of heat.

Good point, but the idea of using a chain is less friction. If the chain were unlubed enough to create this much heat, the bike would be very hard to pedal!

leob1 12-27-06 10:18 AM

You burned a 'rookie mark' into your leg?

Eatadonut 12-27-06 12:30 PM

Quote:

Originally Posted by leob1
You burned a 'rookie mark' into your leg?

Never understood why it was called the rookie tattoo. I've never considered a small grime spot on my right calf a big enough annoyance to stop leaning against my bike, anymore than I would stop walking across the grass because it gets dirt on my shoes.

chephy 12-27-06 04:34 PM

No, I've never been burnt by a chainring.

But thanks for reminding me of the summer. :)

boyet 12-28-06 03:09 AM

Wow that's hot! but I'm not experiencing yet here in our country.

mike 01-12-07 05:08 AM

Quote:

Originally Posted by hotbike
That chainring may have been a lot hotter than 100 deg.

You have to take into account the heat generated by FRICTION.

From your description, you didn't have enough oil on the chain.

If you had more oil on the chain, you would have seen a black, greasy mark on your calf, not the red blister you described.

Riding hard definitely had something to do with the temperature of the chainring. Without oil, metal on metal friction can create lots of heat.

Yes, the chainring was for sure more than 100 degrees because the ambient temperature was over 100 degrees.

Of course, I had a grease mark on my leg too, but when I washed it off, I had burn blister in the shape of the chainring.

I know what you mean about lubrication, but this was a tour, so I oiled the chain before the trip.

I wonder how hot the chainring could have gotten?

digger 01-12-07 08:38 AM

Quote:

Originally Posted by mike
I was going on a tour awhile back and had an unusual experience. It was a HOT day - over 100 F mercury. The heat was glaring off the road.

We were riding pretty hard which may have had something to do with it, but when we stopped for a break, my calf touched my chainring. The chainring was HOT and it burned my calf to the point that I got a perfect chainring blister burn.

It looked cool after the blister popped and it turned into a red-brown chainring scab.

I thought this was very unusual. Has it happened to anybody else or have you heard of it?

Not on a chainring, but....

I rode the Cabot Trail in Nova Scotia last summer (15% grades) and at the bottom of a 8km downhill I stopped to see how hot my rims were...

Holyfrickinjeez that hurt......

Halfstep 01-12-07 09:30 AM

I never burned myself that bad, but yeah, I used to get singed all the time by various parts on my bike when I lived in the Mohave Desert as a kid. Our first summer there, it hit 133F. In the shade. The other thing we learned REAL quick: NEVER, NEVER, NEVER touch the metal part of the seatbelt when you're putting it on. The plastic is there for more than just looks when the inside of a car can exceed 140F.

KrisPistofferson 01-12-07 09:36 AM

My biggest heat-related mechanical problem is sidewall cracking due to excessive heat. I love Pasela TG, but the summer here really cuts their life short, it seems.

noisebeam 01-12-07 09:52 AM

An AZ DOT study on asphault longevity I read a while back found that when the ambient temp is 110F, the surface temp of the asphault can be as high as 180F.
I've found black break levers, black top tube of bike to be too hot to touch while commuting home in 118F (shade temp) while in full sun. I quickly learned not to lean top tube of bike into inside of thigh while waiting for a light to change.
But I have never been burned. Severe burns can occur to folks who walk barefoot, even momentarily on pavement in such temps.
Al

Paul L. 01-12-07 10:23 AM

Yes I remember it well. I had tracked Dr. Cager to his all but innaccessible secret lair. Thinking I had the drop on him I was ambushed and taken into his garage of gas guzzling gargantuan SUVs. Strapped into a seat and unable to move he began to interrogate me.
"Tell me how to defeat the evil League of American Bicyclists and I will let you go Bicycle Man!" he said!
"No never! I will never betray the League of American Bicyclists Dr. Cager!" I retorted and spit on him in an ironic twist.
"Fine" he said, We have ways of making you talk he said as he brandished a red hot chainring from my very own bike.......

Is this the end for Bicycle Man? Will the SUV wielding Dr. Cager triumph in his evil plan to defeat the LAB? Stay tuned for the next episode, "a fist full of chainring fury". Same bike time, same bike channel.

GaryA 01-12-07 11:31 AM

Quote:

Originally Posted by leob1
You burned a 'rookie mark' into your leg?

I was thinking it would make a b*tchin scar. :D


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