evanwellens Lo.

I have an older Gary Fisher mountain bike that still is lots of fun but recently while transporting it with another bike the inner chain ring got badly warped and so I not longer have lower gears. I thought it would be a easy fix, but I can't even find the part to match.I found sheldon brown's post on the matter did my meansurements , but nothing matches what I have. 5 bolts with a adjacent spacing of what looks like 1.5 inches. Nothing on the chart comes close. So my question is there a way to find this part ? Subsitute ? or is it better to replace the crank and would I have to worry about that being a fit ?

Thanks in advance for any words of wisdom!!!

Iride01 

Chain rings might be a cheaper fix if you know the things you need to know. PCD (pitch circle diameter) being one of them which I've only seen expressed as millimeters. I'm not the best and wanting to know everything I need to know about ring sizing and what works with what. So I usually just buy an entire new crank.

Being willing to change to another type BB lets you have a broader selection of cranks. But then you need to know stuff about the BB shell that is on your bike. What type threading, the width from one side to the other, the diameter.

Do you have the tools to do any of this? Changing the cranks and BB will require tools that you might only use once in your life because other bikes use a different type BB and that will require a different tool. So if you don't want to get into all that, letting a bike shop do this for you will be less expensive in the short term. But if you are looking at the very long term or just simply enjoy the DIY, then go for it. Others will have some more detailed info.

Welcome to BF!

sovende

Here’s a link that might help you out with your issue, https://www.wolftoothcomponents.com/...e-diameter-bcd
Once you know the proper “BCD” you should be able to find a suitable replacement.
I’m having some difficulty imagining the situation where transporting two bikes resulted in warping the inner chainring on one of the bikes AND that being the only damage reported!

evanwellens Lo.

BB ? Ball bearings ? I didn't realize they would need replacement too. I did order a crank tool and am very handy , but from your comments sounds like more trouble than it's worth. Problem is bike stores nearby are either extremely expensive or will only service bikes they sell. Would be a bummer to loose the bike over such a (seemingly ) simple part

evanwellens Lo.

I agree didn't make sense to me either , but went riding one day and the next went to ride and the chain ring ( inner yet???? ) was bent out of shape. Only thing I could think of was somehow on the road one bike caught the other in an odd manner. Will check out the link... As mentioned my adjacent bold spacing doesn't appear to be listed. Either way it seems I still need to get the crank off as the inner ring wont slide off like the 2 outers did.

Iride01 

BB = bottom bracket.

Crank tool or bottom bracket removal tool? I'm not sure what I'd call a crank tool. Do you know that you got the one that is for your type crank or bottom bracket.

I have several in my tool box. Quite a few of them I only needed once.

Don't let one bike shop determine your view for all bike shops. You have to visit them all. In some areas there are even people that do mobile services and will come to you.

nathand

Can you provide any photos of the crank? Is there a model number marked on it (for example, if it's Shimano, something like FC-M32 marked on the inside of a crank arm)? While you won't be able post photos here until you have a few more posts, you can upload them to your gallery on this site, and then someone helpful can share them for you. Older mountain bikes may have unusual dimensions for the small inner chainring. In some cases the chainring is riveted, not bolted, and you can't replace it separately.

Depending on the age of the bike there's a good chance you have a square-taper bottom bracket. If so, removing the crank with a crank-pulling tool is straightforward. This will give you access to the inner chainring, and if you can't replace it separately, it's not difficult to replace the entire crankset.

dedhed

BCD - Bolt circle diameter

​​​​​​https://sheldonbrown.com/measure-bcd.html

evanwellens Lo.

Thanks that sounds great... Here is the photo in shared via my phone

http s: //photos.app.goo.gl/NL9LXVoBeuiGrvDq7 ( I put in a space to help it post , not sure how to use the gallery )

If other angles etc would be better let me know and I'll take more

dedhed

You need to measure BCD and/or tell us what model crankset it is. "looks like" isn't close enough.

If you find that number it'll be a lot easier than guessing. Once you find a chainring now would be a good time to service the BB or replace with a cartridge unit.

Depending on the damage you might be able to straighten your existing ring.
​​​​​​https://sheldonbrown.com/measure-bcd.html
https://www.sheldonbrown.com/cribsheet-bcd.html


​​​​​​

evanwellens Lo.

OMG I wish I saw this before taking everything apart

Iride01 

Shimano calls it pitch circle diameter. Open the details for any Shimano Crank. Click the arrow to expand the specs and look near the bottom......

https://bike.shimano.com/en-US/compo.../crankset.html

There is another way to describe the holes position for machining the piece that sometimes uses the distance between the holes which I think is where pitch comes from and the number of holes. However the math for the circle, whether it's BCD or PCD gives you the same circle diameter. Sometimes the pattern is defined by the number of degrees the holes are apart instead of their distance apart. I think but don't know for sure, that is how BCD works.

Pretty much the same thing though I have seen differently worded definitions that essentially wind up with the same thing.

https://owlcation.com/stem/How-to-Ca...he%20chainring.

Iride01 

OP's pic link......

https://photos.app.goo.gl/NL9LXVoBeuiGrvDq7

It's google photos site which sometimes gives issues for BF's attachment manager to load. But just click the link if you are interested.


For the OP..... Untill you get 10 posts, you'll be limited on pic posting and hyperlinks. There is a gallery here you can upload too and sometimes we can find your picd there.

imgur.com works very well as a site to upload pics to and lately hasn't been an issue for putting the pic in a post..... once you get past that 10th post. Google photo's off and on, has given issues. Lately it's been troublesome.

RobertUI 

evanwellens Lo. if you do in fact need a small (granny) chainring and it's an older Gary Fisher (like pre-2002?) I might have a couple, and would be happy to mail to you for the cost of postage. I somehow accumulated a lot of these over the years. If you can post s picture, or can link to one just like yours, that would be helpful to know if what I have will work for you. Model name and approx year might be enough, I worked at a GF dealer 'back in the day'.

-peace

edited as I see we were posting at the same time. I've def got one that I can send for the cost of postage.

dedhed

This seems to indicate a 94/58 mm BCD.
https://bikerecyclery.com/sugino-imp...inrings-1990s/

This one indicates 74 mm BCD
https://www.ebay.com/itm/28439115714...4AAOSwPVJhBIfL

And look Sugino uses PCD as well! Never heard it called that.
https://www.suginoltd.co.jp/store/pr...?product_id=27

evanwellens Lo.

Sorry the system wouldn't let me reply for 24 hr... Guess my newb status...
Thanks that might work.. If not too much trouble can you send the measurement so I can be sure it's a fit ?

evanwellens Lo.

Just realized this isn't going to work for me as it's the inner chain ring that's damaged. Although I am going to try to straighten it once(if) I can get the crank off.

RobertUI 

I'll send some pics this evening... sorry I wound up being offline for most of yesterday.

evanwellens Lo.

Thanks that would be awesome

hokiefyd 

If the distance between two adjacent bolt holes (measuring center to center) is about 1.5", that's 38.1mm, and is likely closer to 34.1mm, indicating a 58mm bolt circle for the small/inner ring. A 58/94 crankset is consistent with an older mountain bike that presumably has a triple crankset.

https://sheldonbrown.com/cribsheet-bcd.html

Given the picture posted from the Google photo gallery -- that very much looks like a 58mm small ring. evanwellens Lo. I may have a part that will work for you as well, if your first few resources above don't work out. Private message me if interested.

evanwellens Lo.

Just an update.. First so many thanks for all the wisdom shared !!!! Since I really want to get out on the road and local stores don't seem to be able to help me out or have the time, I went with trying to re-bend the chain ring back.. It appears I am missing one bolt / spacer.. But looks pretty on and the gears appear to shift without throwing the chain.. A good temp solution for now and hopefully get's me back out there ( if it ever stops raining ) this weekend... Thanks again all !!

trailangel

You are missing a bolt? You will bend the chainring again in no time.

evanwellens Lo.

It's a 5 bolt system... Hoping it will hold up.. Not sure how to replace the bolt on such an outdated part... Will take it for a spin over next few days and see.

dedhed

​​​​​​https://www.benscycle.com/sugino-imp...BoCXvUQAvD_BwE

Pantah

I happen to have that exact crank hanging around complete with chainrings. If I can get my hands on it (no idea off the top of my head where I put it), it's yours for the cost of shipping.