Chainring Compatibility on Triple
 

I’ve decided to get a triple crank for my 7 speed freewheel, so I’ve been looking on Ebay and Craigslist for the usual – Sugino, Sakae, Takagi, and Shimano FC-6206 with 110/74 bcd. I am finding plenty to choose from, but none of them have the exact combination of chainrings I want: 50 outer, 34 or 36 middle, 28 or 30 inner. Most have the 28 or 30, so I would need to replace the outer or middle, and searching for an individual chainring has proven mostly unsuccessful. It seems there aren’t many used ones out there, and the new ones are about $40 on up.

Today, it occurred to me that if the triple I end up with has a 28 or a 30, but not a 50 outer or a 36/34 middle, maybe I could use a chainring off of my current Shimano Claris 50/34. to swap outer or middle. My Claris is 5 bolts, 110 bcd, so either chainring should fit as a replacement. I know Claris isn’t top of the line, but other than that, and maybe looks, are there reasons anyone would recommend against this?

Or, could I get triple crank arms, use my Claris 50/34 chainrings, and then buy a 28 or 30 chainring?
Thank you, in advance, for your advice!
Brian

50/36-34/28-30 is an unusual combination; I would not expect to find more than one or two of those on a complete crankset.
Gotta be patient and keep looking on eBay. Pounce when you find the right tooth count and BCD.
Over the last two months I’ve sold off maybe 20 hardly used chainrings, including a 50 big and a couple of 36 tooth middles & 28 inners, mostly for $12-18 including shipping.

What is the low gear you're trying to achieve? If you currently have a 28-tooth large cog on your freewheel, maybe you could swap that out for one of the Shimano Megarange 7sp freewheels with a 34-tooth large cog. the 34/34 combo will give you same gear inches as the 28/28 combo.

Modern bike has some options that are pretty close.

https://www.modernbike.com/sugino-xd600-cranksets

https://www.modernbike.com/origin8-t...48-38-28-black

https://www.modernbike.com/sr-suntou...8-38-28-silver

https://www.modernbike.com/sunlite-a...2-42-30--black


Unrelated, but this is a fantastic deal.
https://www.modernbike.com/sugino-xd...110-175-silver

Hmm, and here's some bare cranks that would work for you, if utilizing your already existing 50/34 rings.
https://www.modernbike.com/sugino-xd...110-170-silver

And the cheapest chainring I coudl find on ebay: https://www.ebay.com/itm/QBP-Chainri...gAAOSwr8he3lQw

edit: Forgot you want an inner 28t/30t ring. Here's a 30t campy ring for $20.
https://www.ebay.com/itm/Campagnolo-...4AAOSwBY5d03DH

Thank you for the suggestions!
rccardr – I really like the 50/34 with my 14-28, and would like to keep that and have the option of the 28 when needed. I have seen chainwheels in the price range you mentioned, so thank you for reminding me. Perhaps I need to be patient and save some money in the process.

noobinsf – I have thought about the megarange, but that would involve losing the 28 on the freewheel which has been fine for most of the climbing I do and changing my rear derailleur, a Shimano 600 - which I’ve been told can handle a triple. I do own a long cage derailleur if it turns out I need one. I want to do a few more difficult climbs, which is why I want the option of having the 28 chainring available.

piff – Thank you for all those links! That Sugino XD600 looks nice, but unfortunately is out of my current price range. The other ones are definitely something to think about. I would like to stick with 5 bolt, 110 bcd, which the Origin8 is. I have heard mixed reviews about those chainrings, but will look in to that some more. Wow! Thank you for the Ebay ideas, and I added them to my watch list!
Finally, are there any pros/cons on using one of my Claris chainrings to swap out an outer or middle on a triple? Or use them both, and buy crank arms and a 28 or 30? Thanks, again!

I dunno about everyone else, but I consider chainrings along with rear sprockets (not to mention chains) to be consumable items to some extent. So I'm less concerned about what I can snag as a bundle with a new crankset, than what is available in terms of new or used chainrings in the relevant BCD sizes.
Therefore, I recommend you research what replacement chainrings are available for your inner/middle/outer chainring preferences, and then select a crankset that supports the available BCD sizes.
Hints:

• 110 and 130 BCD outer/middle are very common (i.e. lots of available chainring tooth counts)
• 74 BCD inner is very common (i.e. lots of available chainring tooth counts)
• 144 BCD outer/middle used to be common, and with a 74 BCD inner it can also be a good option
• other sizes are rather specialized and you will be going down a rabbit hole if you choose a crankset with other than the above mentioned BCD sizes

That's what I was hoping. The cranks I've been looking at are 110 BCD which is the same as my Claris. So it looks like if I decide to use any of those chainrings, I should be good to go.
Thank you for your help!

It's an unusual combination because it probably won't work well. For the chain to upshift from the granny to the middle reliably, the chain has to get caught by the middle without coming into contact with the outer ring. The 50-36-28 might work... the 50-34-30 probably won't. With the latter combination the chain will shift from the inner to outer chainring, bypassing the middle.

IMO, it would be better to install a larger middle chainring, something appropriate for the majority of your riding. I've been pretty happy using a 38 or 40 tooth middle chainring with a 11-34 or 12-34 9-speed cassette. With a 48 tooth outer I'm able to to do most of my riding on the middle and outer rings. I have a 24 tooth inner ring for when stuff gets super-steep.

110mm bolt pattern rings are available from Origin8:
https://www.amazon.com/Origin8-Alloy...dp/B002G363XM/
I haven't tried them so I don't know how well they work. Like RCCARDR, I have a box full of used chainrings in various states of wear.

I was trying to stay away from suggesting actual ring sizes, but my experience has been similar to yours.
A 50/34/24 did not shift well for me. Lots of skating up and down, not very reliable from ring to ring even with correct chain line and several different triple FD's.
Migrated to a 48/36/24 (12 tooth spacing) and that has worked well on several bikes. Right now only have one bike with a triple- the 83 Davidson Discovery- and that shifts well with that combination.

Jeff, thank you for your advice on the 50/34/28! I like your suggestion of a 48 outer, but I'm somewhat limited since I have a 7 speed 14-28 freewheel. I spend most of my time on the 50/18 or 16. The 50/14 is usually plenty, although I do spin out occasionally. I would love to upgrade my wheels to a cassette so I have more options, maybe someday.
rccardr, I appreciate you confirming what Jeff suggested, and thank you for your recommendations. Both of you have been very helpful, and I am glad you guys took the time to respond. I have one last question. You mentioned 12 tooth spacing as being your preference. Is having at least 12 tooth spacing more important between the inner and middle chainrings? I have friction, so I was thinking I would just adjust as needed. Although, I haven't seen any with a 34/28, so based on what you've told me, I need to toss that idea. I have seen some 36/28 as Jeff said, but will need to look into how well that works.

I don't have enough experience with triples give you an exact answer on optimum chainring spacing. But when I was frustrated with the poor shifting on my Voyageur 650b, I chatted with the top mech ar my local LBS. He suggested the 48-36-24 combination and called it 'classic mountain bike gearing', which was useful since O was using Deore MTB derailleurs and cranks. Worked a charm, so did the same install (but with a Sugino crankset) on the Davidson and haven't felt any need to mess around with it. 48/12 combo gets me to the high 20's before spinning out, and the 24/34 combo lets me pull up any hill I've ever met.

What rccardr said.

In my experience, you can have only so much spread between the 2 outer rings. The middle tooth count doesn't really matter. If you're going to run a 52 big ring, about 30 is the smallest you should go on the granny. So a 28 granny would mean a drop to a 50. Smaller than 28 means you'll need to run a big ring smaller than a 50.

Seypat, using your examples, are you saying that there should only be a 22 teeth difference between outer and inner rings? I'm going with a 50 and 28, so that's in that range. However, looking at what rccardr uses, 48/36/24, there is a 24 teeth difference. I am probably misunderstanding you, and I'm sure there are many variables involved between derailleurs, etc. You also state the middle tooth count doesn't matter. That is what I was thinking, but others have suggested my idea of using a 34 middle with a 28 inner won't work very well. As a result, I was leaning toward going with a 36. I've looked at a gear chart and think I will be okay since I will now have the 28 inner. I guess it will just be a matter of how well things will shift. It seems like there are more things to think about than I planned, which is why I am glad I asked. Everyone's advice has been helpful and certainly saved me some money in failed attempts!

Let me read back through the whole thread again to give you a complete answer.

I read back through the thread. I generally run a 52/40-42/30 triple up front. The rear cluster is a 5-8 speed with a 11-14 small sprocket and a 28t big. That works well for me because I am a masher more than a spinner. The 52/42 is good for most riding with the 28 in back. The 30 3rd ring is there for when it is needed. There is a climbing ride that rccardr and I do each year which I have a triple crankset made up with a 50/36/28 that I put on for that ride. I tried a 52/36/28. It would not work. The front derailleurs I tried were not MTB specific wide range derailleurs. With the 52/28 combo, the chain would hit the cage roller at the bottom of the FD cage. With the 52/30 or the 50/28 it would not. I don't know about a 50/26. Once you get into the 26 and 24t range, then you are in the range of classic MTB gearing which rccardr talks about. Whole drivetrains were designed around gearing like that.

The 50/36/28 I have shifts well, but it is only practical for that ride. The 50t is only there to get me through the first 20 miles where there is not a lot of climbing over all. The bike is intentionally geared low for that ride only. The point Jeff makes about having a small chainring is probably valid when it comes to shifting. A bigger middle ring would be more practical for everyday riding anyway, if you are going to run a 14t sprocket in back as your highest gear.

All I use are triples. The reality is you will have to purchase at least one ring, maybe 2. Or a different freewheel/cassette with a higher(smaller tooth count). Or some combo of both. Go to a gearing calculator, play with the numbers and figure out what will work for you. Then figure out the cheapest way to do it. That's the best advice I can give.

If your freewheel is in good working order, also consider swapping one or more sprockets to properly complement your chosen chainring combination.
Many people regard a freewheel as a monolithic unit, but in truth it is an assembly, and customizing the combination of sprockets was just as common BITD as it is on cassettes today.
What you need to embark on this adventure is a couple of sturdy chainwhips (perhaps these can be borrowed from your local bike coop or friendly LBS) or 1 chainwhip and a freewheel vise of some sort (can be improvised). Be prepared for possible destructive removal of the small sprocket. Sometimes these are just on too tight for non-destructive removal, but that's only happened to me in one out of dozens of freewheel teardowns.
Replacement sprockets are readily available. Preferred acquisition method is via teardown of a donor freewheel. Individual sprockets are also available on Ebay, or can be traded with members on BF. For interchangeability, it's best to stick with one brand/model, until you learn the nuances.
As you teardown you will quickly see that there are specific positions for sprockets as they go from small to large, so the incoming sprockets have to be selected for the position for which they are wanted, as well as their tooth counts
If all this seems too much for a beginner, you could try Pastor Bob's freewheel service. I'm sure he could fix you up with a customized freewheel at reasonable cost.

Your advice is well received and thank you for the detailed response. That is good news to hear about your FD handling the 50/36/28, as that is what I am leaning toward. I have a Shimano 600 FD and have read elsewhere, probably in previous posts from you, that it can handle a triple. Thank you for clarifying the teeth range and how MTB derailleurs are set up for that. I was thinking of getting one, just in case, but will hold off on that. Thank you, again, and I'll let you know how things turn out!

If you are cruising the Bay for chainrings, go at it from all angles. After the usual size searches of BCD and teeth count, search the individual vintage brands. There is usually some decent deals for SR Sakae chainrings.

Assuming the OP's crankset is 110 BCD, this might also be an option: https://www.interlocracing.com/shop/...triplizer-2808

It replaces the original inner chainring with a 34 or 36T ramped and pinned ring, with mounting points for a 74BCD inner ring, thereby creating a triple set where there was originally a double. A new wider bottom bracket may also be needed.

As others have said a 34 middle ring will often be over-ridden when trying to shift to it from the inner ring.

What kind of riding are you doing/planning to do?

My touring MTBs have 24-36-48 or 26-38-48 chainrings. They are old school cranksets similar to the Sugino one linked to upthread.

You might consider loting on Craigslist, Kijiji and any other for sale sites for a used MTB from which you can take the triple crankset and bottom bracket. I say that becuase a while back ( a number of years ago) I came across a fellow living out in the country who fixed and sold bikes and charged $40.00 each for them. Over the years I bought a number of MTBs from him that old-school Shimano Deore components, or at least crankset and derailleurs on them. I got them to keep as spare parts.

Approximately where are you located?

Cheers

I wanted to build a 26-38 crankset using my unused 74/110mm bcd cranks. After searching for some time, i found that those sizes are not common or cheap. I ended up using 64/104mm bcd.

28-30 and 34-36 are not common in 74/110mm.

Since you are using 7 speed freewheel, i assume you have a 14t small cog?

50x14 gives 96.4 gear inch.

May i suggest getting 64/104mm bcd cranks. 28t and 34t chainrings are common. 50t singlespeed/narrow wide chainrings are available. But easier and cheaper to just get 48t.

48x14 gives 92.6 gear inch.