Chainring crash damage

Andrei Petrov

Andrei Petrov

Member
I slid on a gravel patch in a low-speed turn and dug some teeth of the 52 ring into the road. A couple of teeth are bent inwards. This must be a common "injury" with Cruzbikes? Will I be ok filing/bending those teeth back into straight, or will I regret it? The shifting seems fine on the workstand even before repairs, but I have not shifted under load yet.

I run an Ultegra triple. Any replacement rings I can find seem to be for a double, either 50 or 53t. These should work, right? Or is this an opportunity to go oval?)
 

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trapdoor2

trapdoor2

Zen MBB Master
I myself would probably hammer n dolly them back as straight as I could, gently file any sharp spots off and ride it until I could find a replacement.
I think either 50 or 53 should work fine as long as they are spec. for a triple.
 
McWheels

McWheels

Off the long run
A bend, and then another bend back shouldn't be enough to fatigue the metal. Unless they're made of something a bit more brittle, but I suspect not.

Smooth them out and you ought to be alright to just crack on until you get bored of the setup completely. Also look at it this way, for a big ring you will have roughly half the teeth in contact with the chain at any 1 time. If you lose 1 or 2 it really won't make a massive difference, except maybe to your sense of propriety.
 
Tigerpaw

Tigerpaw

Well-Known Member
I did the same last weekend.... controlled the crash so it was in the grass and not the pavement. The chainring was all dorked up. It was replaced when I got home as I'm not fooling with re-bending it.:)
 
super slim

super slim

Zen MBB Master
Some old 10 speeder bikes only had every 3 rd tooth on the big STEEL chain ring, to save weight, OR speed up gear changes before ramps and pins were developed!!

Remember that on a 11 tooth rear cassette, only 5 teeth contact the chain.

62t%20and%2048t%20half%20ovals.jpg


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Andrei Petrov

Andrei Petrov

Member
Well, I've done a few rides, and shifting is unaffected... except for several over-shifts when the chain would have been dropped from the big ring had I not stopped pedalling. On closer examination, the section with the damaged teeth seems to be bent inwards a little. I could not see this when I took the ring off, as the bolt contact points are all true. This seems to be rather difficult to make true, I will probably try hammering it gently with a rubber mallet.

A chainring guard is a great idea, I will try one. Those Ultegra parts are expensive.
 
Andrei Petrov

Andrei Petrov

Member
ak-tux said:
I think all Short Wheel Base recumbents and trikes should have a chainring guard installed to protect both the chainring itself and other humans. They are easily available on ebay. I got one for my DIY recumbent.
View attachment 5047
View attachment 5048
Click to expand...
This makes so much sense! How do you size these guards - would a 52 t guard go ober the 52t chainring, or do you need to upsize the guard? They probably require longer bolts to fit over the chainset?
 
B

Brad R

Well-Known Member
Andrei Petrov said:
Well, I've done a few rides, and shifting is unaffected... except for several over-shifts when the chain would have been dropped from the big ring had I not stopped pedalling. On closer examination, the section with the damaged teeth seems to be bent inwards a little. I could not see this when I took the ring off, as the bolt contact points are all true. This seems to be rather difficult to make true, I will probably try hammering it gently with a rubber mallet.

A chainring guard is a great idea, I will try one. Those Ultegra parts are expensive.
Click to expand...

I recently sold a bike and shipped it to California. The chainring got bent during shipping. The buyer was having a brace on the seat welded back in place. The welder heated the parted and flattened it. He said it turned out as good as new.
 
ak-tux

ak-tux

Zen MBB Master
Andrei Petrov said:
This makes so much sense! How do you size these guards - would a 52 t guard go ober the 52t chainring, or do you need to upsize the guard? They probably require longer bolts to fit over the chainset?
Click to expand...
Yes, 52T goes with a 52T chainguard, similarly a 53T will need a a 53T chainguard. But I found out that a 52T can also fit my 50T chain ring quite fine. Therefore on my 50T chairing (a shimano Sora triple), I used a driveline 52T chainguard.

The driveline brand I shared above comes with a set of spacers, and longer bolts and nuts to replace the existing ones on the crankset spider.

Another important parameter to consider is the BCD(Bolt cycle diameter) for your big chainring. Make sure you buy the correct one that matches your crankset. The compact systems will have a BCD of 110mm while the standard will have a BCD of 130mm
driveline-s-l500.jpg
crankset--chainring-guard-1.png
 
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Andrei Petrov

Andrei Petrov

Member
I just realized that my Ultegra triple does not have through-bolts - the bolts are screwed into the big ring from the inside. So it would be impossible to mount the chain guard. Oh well.
 
ak-tux

ak-tux

Zen MBB Master
Andrei Petrov said:
I just realized that my Ultegra triple does not have through-bolts - the bolts are screwed into the big ring from the inside. So it would be impossible to mount the chain guard. Oh well.
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Sorry, I had not noticed the Ultegra's unique bolt design.

I wonder if a standard chainring can be used as a replacement on the the same Ultegra spider? Then it will allow you to use the driveline chainring guard.
ShmoUltSLFC6604G-1lg.jpg

Alternatively, if your bottom bracket shell allows it, may be a different chainring guard design would help but probably it will not fit on a vendetta either:
chainringguard6501-teratrike.jpg

From http://www.utahtrikes.com/PROD-497.html

It's way too expensive in my opinion. $75 for a chainring guard!
 
Andrei Petrov

Andrei Petrov

Member
ak-tux said:
Sorry, I had not noticed the Ultegra's unique bolt design.

I wonder if a standard chainring can be used as a replacement on the the same Ultegra spider? Then it will allow you to use the driveline chainring guard.
View attachment 5153

Alternatively, if your bottom bracket shell allows it, may be a different chainring guard design would help but probably it will not fit on a vendetta either:
View attachment 5152

From http://www.utahtrikes.com/PROD-497.html

It's way too expensive in my opinion. $75 for a chainring guard!
Click to expand...
I will need to look into whether a different chainring would work. In the meantime, I am attempting to straighten the damaged ring.
 
DavidCH

DavidCH

In thought; expanding the paradigm of traversity
ak-tux said:
Sorry, I had not noticed the Ultegra's unique bolt design.

I wonder if a standard chainring can be used as a replacement on the the same Ultegra spider? Then it will allow you to use the driveline chainring guard.
View attachment 5153

Alternatively, if your bottom bracket shell allows it, may be a different chainring guard design would help but probably it will not fit on a vendetta either:
View attachment 5152

From http://www.utahtrikes.com/PROD-497.html

It's way too expensive in my opinion. $75 for a chainring guard!
Click to expand...
That's an old Shimano Ultegra crank. New ones have 4 bolts.

Has anyone seen elliptical chainwheel guards (Not that I would ever imagine putting one on)? :rolleyes:
 
super slim

super slim

Zen MBB Master
Andrei Petrov

Andrei Petrov

Member
super slim said:
http://www.ebay.com/itm/litepro-Folding-Road-Bike-Chainring-Chain-Ring-BCD-130mm-45-47-53-56-58T-w-Guard/282469932919?_trksid=p2141725.c100338.m3726&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=20150313114020&meid=20ca8b742f8742de851394867636227c&pid=100338&rk=1&rkt=29&sd=302349641730&var=581617429936

If the ultegra chainring is 5 hole then this would replace the 53 T, PLUS include a chainring guard in one, and only costs $18 US with shipping, and be very light.

Ak-Tux's Driveline chainguard comes with longer through bolts and spacers, so just drill out the outer ring threads.
http://www.ebay.com/itm/like/302349...730&catId=888&mid=503280&sortbid=5&rmvSB=true
Click to expand...
That's a very good option, thanks! Does anyone here ride with bigger rings - 56 t and beyond?
 
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