Older MTB Looking for Newer Chainring Guard Solution
#1
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Older MTB Looking for Newer Chainring Guard Solution
Let me preface this by saying that I’m a complete newbie when it comes to bikes in general, and feel dumb asking the following question.
So, I have an old Diamondback mountain bike that I purchased back in 2007. This bike has three gears in the front, and I want to install a chain ring guard to protect the gears. The largest gear has 42-teeth with a BCD of ~135mm; can anyone help me select the appropriate guard for my use case?
I’ve attached a photo of the front gears of my bike for reference, areas marked in Green.
So, I have an old Diamondback mountain bike that I purchased back in 2007. This bike has three gears in the front, and I want to install a chain ring guard to protect the gears. The largest gear has 42-teeth with a BCD of ~135mm; can anyone help me select the appropriate guard for my use case?
I’ve attached a photo of the front gears of my bike for reference, areas marked in Green.
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I'm not sure those are bolt holes, and 135mm isn't a 4-bolt BCD standard that I know of.
https://www.wolftoothcomponents.com/...e-diameter-bcd
https://www.wolftoothcomponents.com/...e-diameter-bcd
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I just did a quick search and turned up a bunch of possibilities. If you check some of the ebay, etc. cheaper versions than the Truativ OEM's they may list the guards bolt hole distance. Shouldn't be hard to find one that works. Avoid the plastic versions if you want real chainring protection. (1) chainring guard for truativ cranks - Search (bing.com)
#5
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The problem I am running into with my crankset (besides being old) is that a) it uses a four-bolt design, and b) the holes are so far apart. If I find a chainring guard with a four bolt design, nine times out of ten, the BCD is 104mm, much smaller than what my crankset is calling for. However, I have noticed that with the five-bolt crankset design (which my MTB does not have), there are chainring guard options which offer larger BCD's.
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Curious: what kind of obstacles are you encountering, and how often are you bashing the chainring into them?
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Look for an 80s BMX frame-mounted guard?
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I'm pretty sure those aren't bolt holes; the countersink appears to be the wrong way, towards the inside of the rings, as opposed to the face.
Generally, "bash guards" mount to the chainring bolts, which are much larger than those little holes around the edge of the rings themselves. They either mount like a 4th chainring, or in place of the existing big ring.
The only guards I've come across that mount to the edge of the ring itself are the plastic "protectors" that you find on hybrids ad recreational bikes; which are really there to protect your pants leg from the chain, than protect the chain from obstacles.
Generally, "bash guards" mount to the chainring bolts, which are much larger than those little holes around the edge of the rings themselves. They either mount like a 4th chainring, or in place of the existing big ring.
The only guards I've come across that mount to the edge of the ring itself are the plastic "protectors" that you find on hybrids ad recreational bikes; which are really there to protect your pants leg from the chain, than protect the chain from obstacles.
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IMO, getting stuff (branches? leaves? squirrels?) caught in the gear isn't really an issue. I think chainring guards are helpful if you're riding through boulder fields, climbing ledges, or scrambling over a lot of tree trunks, but for most situations I've rarely found them necessary. I don't know if I've ever had a non-bmx bike that had one.
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Those are not bolt holes. If you put bolts in them, they will get caught on the chain. If you don't think so, put a bolt in one of the holes, put the chain in the middle chainring and turn the crank.
#12
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So, from what I gather, this essentially means that the "BCD" I originally posted is incorrect, and the actual measurement I should be taking for the BCD should be the bolts that are holding all three of my gears together. I've attached a photo of the new BCD measurement; is the manner in which I have measured the real BCD of my MTB correct?
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https://www.ebay.com/itm/32517806140...MAAOSwZoZidP10
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Huzzah! Thanks for the link my friend. Gonna try this out.
Last edited by Entropy_S; 05-25-22 at 07:30 PM. Reason: Grammar
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