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FD and cransket compatibility issue ?

Old 03-12-18, 09:30 AM
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adablduya
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FD and cransket compatibility issue ?

greetings: this may appear somewhere in this forum, but going for it here just the same....

with a recently acquired used bike, i have been having issues with front derailleur shifting. the bike has a Tiagra 52-42-30 crankset and a Shimano XTR triple front derailleur. major problem is shifting from the middle (42t) ring to the big (52t). the bottom of the inner cage rubs against the teeth of the 42t. tried tweaking the height of the FD, but just can't seem to get the shifting to be right. made all necessary adjustments to limit screws, etc.

so, my research on this seems to point to the FD not being compatible with this crankset in that the FD is designed for a 50T max ring, and i think a 12t minimum delta is required between the large and middle ring. would you guys concur with that assessment ?

another question: with a 50-39-30 crankset: how much smaller of a granny gear can i go ?

thanks for any thoughts on these....
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Old 03-12-18, 09:44 AM
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Tiagra is part of a road bike system. XTR is a MtB part. The two are not meant to be cross compatible when an indexed front shifter is used. Since we don't yet have ALL the info we can't assume this is why they don't play nice. But many shops have seen this before, miss matched shifters, ders and cog/crank sets.


I believe your Tiagra crank has a 74mm inner ring bolt pattern. If so then a 24T ring is the smallest that can bolt on. Do know that the smaller diameter of the 24 will locate the chain at a different place within the front der's cage (and the cage's sculpting/contours which are intended to help shifting and reduce chain rub) then with a 30T.


Shimano works really well when kept as a complete/compatible system. Swapping out parts for non system ones usually reduces this performance. Andy
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Old 03-12-18, 09:52 AM
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Your analysis is correct. It's not just the indexing that differs between road and MTB front derailleurs. MTB fronts have a deeper inner cage plate intended to work with chainring of smaller diameter and greater tooth difference than road derailleurs. Your crank has a 10 tooth big to middle chainring difference so if the outer cage plate is set properly above the big ring, the inner plate is too deep to clear the middle chainring. Basically, you have the wrong front derailleur.

Also, it depends on which generation Tiagra triple you have. If it's a 4600 or older, yes the granny bolt circle is 74 mm and you can fit as small as a 24T chainring. If it a 4700 , the granny chainring is bolted directly to the middle chainring with a 92 mm bolt circle and 30T is the smallest that will fit.
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Old 03-12-18, 10:07 AM
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Originally Posted by HillRider View Post
Your analysis is correct. It's not just the indexing that differs between road and MTB front derailleurs. MTB fronts have a deeper inner cage plate intended to work with chainring of smaller diameter and greater tooth difference than road derailleurs. Your crank has a 10 tooth big to middle chainring difference so if the outer cage plate is set properly above the big ring, the inner plate is too deep to clear the middle chainring. Basically, you have the wrong front derailleur.

Also, it depends on which generation Tiagra triple you have. If it's a 4600 or older, yes the granny bolt circle is 74 mm and you can fit as small as a 24T chainring. If it a 4700 , the granny chainring is bolted directly to the middle chainring with a 92 mm bolt circle and 30T is the smallest that will fit.
thanks alot for that feedback. i should have perhaps specified that i am using bar-end shifters, so the front is friction, not indexed. and the question on the granny gear change was for a different crankset (50-39-30) on another bike. no problems with that one at all, just wanted to drop that granny down a bit for my wife !
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Old 03-12-18, 10:13 AM
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.... with a 50-39-30 crankset: how much smaller of a granny gear can i go ?
Yes, It depends on how the 30 t is attached... I have my granny half the tooth count of the big chainring ..

because the 3rd chainring is on a 74mm bolt circle.. [50,40,24] touring bike .. (a)110-74, (b) <c> race triple 135-74.

bar end shifters, freewheels , so 50:13 top gear.. (c) 110-58; 48,36,22t




..

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Old 03-12-18, 10:16 AM
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Originally Posted by adablduya View Post
thanks alot for that feedback. i should have perhaps specified that i am using bar-end shifters, so the front is friction, not indexed. and the question on the granny gear change was for a different crankset (50-39-30) on another bike. no problems with that one at all, just wanted to drop that granny down a bit for my wife !
I wasn't concerned only about the indexing mis-match, but mostly the tooth difference incompatibility between your crank and front derailleur.

As I mentioned above, the 50/39/30 crank can either have a 74 mm granny chainring bolt circle and use a 24T chainring or not and be stuck with the 30T. Earlier Tiagra triples had the 74 mm bcd while later ones did not. Also, the 5700 105 crank was the last Shimano road triple to have a 74 mm granny bolt circle.
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Old 03-12-18, 10:48 AM
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Originally Posted by HillRider View Post
I wasn't concerned only about the indexing mis-match, but mostly the tooth difference incompatibility between your crank and front derailleur.

As I mentioned above, the 50/39/30 crank can either have a 74 mm granny chainring bolt circle and use a 24T chainring or not and be stuck with the 30T. Earlier Tiagra triples had the 74 mm bcd while later ones did not. Also, the 5700 105 crank was the last Shimano road triple to have a 74 mm granny bolt circle.
i'll have to take a closer look at the 30t bolt spacing on the 50-39-30, and then decide. thanks for that info.

so, i'm looking to change out the Tiagra 52-42-30 crank with something else, not sure yet what. BUT, what would be an appropriate / correct FD for that crankset, just for my education ? i sniffed around on the net yesterday, but couldn't find one that spec'd to that crankset.....
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Old 03-12-18, 09:58 PM
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Originally Posted by HillRider View Post
I wasn't concerned only about the indexing mis-match, but mostly the tooth difference incompatibility between your crank and front derailleur.

As I mentioned above, the 50/39/30 crank can either have a 74 mm granny chainring bolt circle and use a 24T chainring or not and be stuck with the 30T. Earlier Tiagra triples had the 74 mm bcd while later ones did not. Also, the 5700 105 crank was the last Shimano road triple to have a 74 mm granny bolt circle.
Thanks again for the helpful info. Question: where do you guys get all this detail on crankset model numbers / bolt patterns, etc. ? Another poster mentioned Tiagra 4600, 4700; you mentioned 5700 105 was the last for the 74mm granny bolt pattern. Where can i get this level of info ?? I looked on my cranks, and donít see these model numbers (maybe not closely enough ??)

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Old 03-12-18, 10:57 PM
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Look on the arm backside about the pedal threaded hole. Most all Shimano cranks in the last 20ish years have had this as the model location. Then with this model number Shimano's website give you the rest. Of course you have to have been around a bunch of years and memorized this or know how to mine their site. There are other on line sources for out of date Shimano info, if you have the time or drive. Andy

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Old 03-14-18, 10:32 AM
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Originally Posted by Andrew R Stewart View Post
Look on the arm backside about the pedal threaded hole. Most all Shimano cranks in the last 20ish years have had this as the model location. Then with this model number Shimano's website give you the rest. Of course you have to have been around a bunch of years and memorized this or know how to mine their site. There are other on line sources for out of date Shimano info, if you have the time or drive.
Andy (and others): thanks a lot for your inputs. Been very helpful. Man, i was thinking you were encyclopedic, rattling off series numbers and such.

So, hereís my deal: due to health considerations, me and my wife acquired a couple of recumbent trikes. Big fun. Anyway, mine has the Tiagra 52-42-30 crank and the (incompatible) XTR FD. Hers has a 50-39-30 with a triple 105. Works beautifully. Mine, not so.

So, im getting her a new Deore 591 48-36-26 and FD. Iím taking her 105 50-39-30 and FD, and going to swap the 30t for a 26t. She needs lower gears and I need gears that work !!! My trike also has a SRAM 3-speed hub, so very nice low gears.....
-

Thanks again.
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Old 03-14-18, 11:35 AM
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Originally Posted by adablduya View Post
Andy (and others): thanks a lot for your inputs. Been very helpful. Man, i was thinking you were encyclopedic, rattling off series numbers and such.

So, here’s my deal: due to health considerations, me and my wife acquired a couple of recumbent trikes. Big fun. Anyway, mine has the Tiagra 52-42-30 crank and the (incompatible) XTR FD. Hers has a 50-39-30 with a triple 105. Works beautifully. Mine, not so.

So, im getting her a new Deore 591 48-36-26 and FD. I’m taking her 105 50-39-30 and FD, and going to swap the 30t for a 26t. She needs lower gears and I need gears that work !!! My trike also has a SRAM 3-speed hub, so very nice low gears.....
-

Thanks again.
Don't do it. If you are going to go through the trouble, make it worth it. The difference between a 30 and a 26 is just perceptible. For the same money as the 48-36-26 you can get a 44-32-22 or a 46-34-24, either of which would be a better choice for the wife IMO. For yourself... what issues exactly are you having with the front shifting? Moreover you have not even mentioned what RD you are using. It matters. You are about to change the 30T for a 24T without making any change to the big ring. This is going to increase your total wrap by a couple to several teeth. I wouldn't lose any sleep over it, but I would be at least aware of it. Also, it isn't because you are using a 3sp IGH why you have 'nice low gears' it is because the size of the rear cog (which is?) that is on the 3sp hub works for you. You can change it. I can't personally see how you can get by with so few speeds, but that's me. The rest of my advice is sound though, I think.

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Old 03-14-18, 12:37 PM
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Originally Posted by Leisesturm View Post
Don't do it. If you are going to go through the trouble, make it worth it. The difference between a 30 and a 26 is just perceptible. For the same money as the 48-36-26 you can get a 44-32-22 or a 46-34-24, either of which would be a better choice for the wife IMO. For yourself... what issues exactly are you having with the front shifting? Moreover you have not even mentioned what RD you are using. It matters. You are about to change the 30T for a 24T without making any change to the big ring. This is going to increase your total wrap by a couple to several teeth. I wouldn't lose any sleep over it, but I would be at least aware of it. Also, it isn't because you are using a 3sp IGH why you have 'nice low gears' it is because the size of the rear cog (which is?) that is on the 3sp hub works for you. You can change it. I can't personally see how you can get by with so few speeds, but that's me. The rest of my advice is sound though, I think.
I did mention above that I have shimano XTR RD with the Tiagra 52-42-30. Additional: rear cog is 11x32 9 sp. The 3sp IGH helps a lot with going low. Iím not following on ďYou are about to change the 30T for a 24T without making any change to the big ring.Ď. My thinking was that iíd be good with changing to the 50-39-30, and swap the 30t with a 26t, as I could use lower gearing. Maybe going to an 11x34 on the back would be good, too. For the wifeís bike, she has a 11x34 9 sp. cogset. My thought with going down to a 48-36-26 would benefit her low end a lot, as well as giving her high-end a bit for the lower, since she doesnít use her 50t much.now, I would not mind myself going to a smaller crankset; was looking more to a save the $$ and recycle the 50-39-30.

So, not sure iím following your train of thought. Please feel free to elaborate, Iím all ears.
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Old 03-14-18, 01:12 PM
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Originally Posted by Leisesturm View Post
The difference between a 30 and a 26 is just perceptible.
It's more than "just perceptible" is a significant difference, giving a 15% lower gear. I agree that a 24 or 22T granny chainring would be even better but a 26 is a worthwhile improvement.
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Old 03-14-18, 01:44 PM
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Originally Posted by HillRider View Post
It's more than "just perceptible" is a significant difference, giving a 15% lower gear. I agree that a 24 or 22T granny chainring would be even better but a 26 is a worthwhile improvement.
15% significant? Depends on who you ask. Or what part of your body... a 15% difference in the feel of the knob of an audio component = significant. A 15% difference in the feel of a given gear = perceptible. But the cost of that difference is the cost of an entire new crankset and installation. The 26T granny gives one more useable gear that is just perceptible. The 22T granny gives two more for the exact same price. More even because the middle ring is lowered as well. Lower gears all around. I know what I am talking about because I have made the same mod before and I am about to do it again.
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Old 03-14-18, 02:00 PM
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Originally Posted by HillRider View Post
It's more than "just perceptible" is a significant difference, giving a 15% lower gear. I agree that a 24 or 22T granny chainring would be even better but a 26 is a worthwhile improvement.
Iím more interested in leisesturmís mention of changing chainrings, along with going lower than 26t. Iím less concerned whether 30 to 26 is Ďperceptibleí; Sure, it would be, but I also agree that the 24 might be a better bang for the buck.
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Old 03-14-18, 02:02 PM
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Originally Posted by adablduya View Post
I did mention above that I have shimano XTR RD with the Tiagra 52-42-30. Additional: rear cog is 11x32 9 sp. The 3sp IGH helps a lot with going low. Iím not following on ďYou are about to change the 30T for a 24T without making any change to the big ring.Ď. My thinking was that iíd be good with changing to the 50-39-30, and swap the 30t with a 26t, as I could use lower gearing. Maybe going to an 11x34 on the back would be good, too. For the wifeís bike, she has a 11x34 9 sp. cogset. My thought with going down to a 48-36-26 would benefit her low end a lot, as well as giving her high-end a bit for the lower, since she doesnít use her 50t much.now, I would not mind myself going to a smaller crankset; was looking more to a save the $$ and recycle the 50-39-30.

So, not sure iím following your train of thought. Please feel free to elaborate, Iím all ears.
I guess I am the one who is not following... so you have a 52/42/30 x 11-32. Where does the 3sp IGH fit into that? Do you occasionally swap one for the other? In any case a 50/39/24 which is what you will have if you swap the granny of your wife's triple to 24T is a wider span than most FD are comfortable with. Personally I don't really care, but you seem to notice small degradations in shifting performance. The real issue is the total wrap of the front and rear spreads together. My Deore Shadow Mount super wide range RD is rated for like 47T of total wrap. I don't know anything about your XTR RD. As for your wife's trike that now has a 50/39/24... going to a 48/36/26 is not a terrible idea but how much does it really help? More to the point, for the exact same amount of money and effort spent in changing to the 48/36/26 you could just max out the capability of the 68mm bolt circle and get the lowest granny that works: 22T. Now she really has some climb anything gears to work with. And a decent top end for going down the other side. Clearer?
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Old 03-14-18, 02:03 PM
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Okay, so maybe this will help. My wife's road bike came with a road triple crank 30-39-50 and a Tiagra 4603 front derailleur. I swapped out the 50t for a 46t and that front derailleur is golden. I'm pretty impressed with how well it shifts with her brifters. I converted it from 10 speed to 8 and she is running Claris shifters. This is of no importance other than to further praise the merits of the 4603 FD. Because it has a 20t capacity I can go as low as 26-36-46 if I need to someday.

You can probably save yourself some $$ and headaches by just getting a 4603 front derailleur, and new chainrings if you want to change the gearing.

John

Edit added: I'm sure there are other Shimano road triples that will work just as well. I only mention this one because in my experience as you go up the Shimano food chain, triple road FD, if even available, do not play well with a 46t chainring. Others may have better recommendations.

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Old 03-14-18, 02:34 PM
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Originally Posted by Leisesturm View Post
I guess I am the one who is not following... so you have a 52/42/30 x 11-32. Where does the 3sp IGH fit into that? Do you occasionally swap one for the other? In any case a 50/39/24 which is what you will have if you swap the granny of your wife's triple to 24T is a wider span than most FD are comfortable with. Personally I don't really care, but you seem to notice small degradations in shifting performance. The real issue is the total wrap of the front and rear spreads together. My Deore Shadow Mount super wide range RD is rated for like 47T of total wrap. I don't know anything about your XTR RD. As for your wife's trike that now has a 50/39/24... going to a 48/36/26 is not a terrible idea but how much does it really help? More to the point, for the exact same amount of money and effort spent in changing to the 48/36/26 you could just max out the capability of the 68mm bolt circle and get the lowest granny that works: 22T. Now she really has some climb anything gears to work with. And a decent top end for going down the other side. Clearer?
Another question: what is Ďtotal wrapí? New term to me.

Ok - to recap:

I mistyped earlier: with the current 52-42-30, the bike has a Shimno XTR FD. It is not compatible with the Tiagra 52-42-30; the inner bottom of the FD wonít clear the 42t., as well as not permit >50t. so looking initially for a FD that will work with this crank. It appears this is hard to find. My bike also has a 11x32 9 speed cassette AND a SRAM 3 speed hub. I like to use the hub because A) the crank shifting is poor and itís easier to use instead and B) i like the low-end when using the 30t chainring. So, deciding to replace the crankset and FD altogether with smaller cranks to get a better range of gears for me.

The wife has a shimano 105 50-39-30 crank and FD, and a 11x34 cogset. So, deciding to replace the crankset and FD. I wanted to get her some lower gearing, so thought iíd Buy her the new crank (48-36-26 or lower) and FD, and I would use her 50-39-30 and FD and swap the 30t for a 26t or 24t.

So, after the replies here, iím a bit confused as to my best actions to A) get one crankset and FD and B) recycle the 50-39-30 with either a 26 or 24. On the Tiagra, the 52/42 combo is not as low as iíd like.

Sorry to appear repetitive.

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Old 03-14-18, 03:09 PM
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Originally Posted by adablduya View Post
Another question: what is Ďtotal wrapí? New term to me.

Ok - to recap:

I mistyped earlier: with the current 52-42-30, the bike has a Shimno XTR FD. It is not compatible with the Tiagra 52-42-30; the inner bottom of the FD wonít clear the 42t., as well as not permit >50t. so looking initially for a FD that will work with this crank. It appears this is hard to find. My bike also has a 11x32 9 speed cassette AND a SRAM 3 speed hub. I like to use the hub because A) the crank shifting is poor and itís easier to use instead and B) i like the low-end when using the 30t chainring. So, deciding to replace the crankset and FD altogether with smaller cranks to get a better range of gears for me.

The wife has a shimano 105 50-39-30 crank and FD, and a 11x34 cogset. So, deciding to replace the crankset and FD. I wanted to get her some lower gearing, so thought iíd Buy her the new crank (48-36-26 or lower) and FD, and I would use her 50-39-30 and FD and swap the 30t for a 26t or 24t.

So, after the replies here, iím a bit confused as to my best actions to A) get one crankset and FD and B) recycle the 50-39-30 with either a 26 or 24. On the Tiagra, the 52/42 combo is not as low as iíd like.

Sorry to appear repetitive.
So you have a Dual Drive rear hub. Maybe you mentioned that. I admit it. I'm late to this thread and haven't read all the prior posts. But you could help us out by being more precise: "I like the low end when using the 30T chainring". And which ratio on the DD? If its the low speed those are some truly low gears indeed. Or maybe you are in the smaller teeth (crosschaining?). I don't know... anything is possible but stupendously low gears on a bicycle can be impractical simply for balance reasons. I have trouble believing you could not get by with your present setup, it is already more gear range than most (two wheel) bikes will ever have.

In your situation I would: Buy the wife the Deore crankset I linked to or similar and the Deore FD to go with it. Take her 105 FD and her crankset. Call it very good. The only reason to change the 30T granny to a 24T would be if you didn't already have an IGH in the rear hub with a 75% reduction. But you do, so I'm not sure of why you want to do this.
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Old 03-14-18, 03:16 PM
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Originally Posted by adablduya View Post
Another question: what is Ďtotal wrapí? New term to me.
Your chain needs to be long enough to wrap around your crankset's biggest chainring and your cassette's biggest cog. Whenever you shift to a smaller cog or smaller chainring, that adds a little slack to the chain. It's the job of the spring-loaded cage on the rear derailleur to take up that slack. Since that slack can be created by shifting the rear or the front, the derailleur specs need to take the total of both front and rear gearing into account. The way we quantify that is the derailleur's wrap capacity.

To calculate wrap capacity, take the difference between the biggest and smallest cog on the cassette and add it to the difference between your biggest and smallest chainrings on the crankset. For example, let's say you've got a 12-29 cassette and a 30-39-52 crankset. You'd need a rear derailleur with a wrap capacity of 39 teeth or greater, as calculated below:

(cassette range) + (chainring range) =
(29-12) + (52-30) = 39
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Old 03-14-18, 03:27 PM
  #21  
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Originally Posted by Leisesturm View Post
So you have a Dual Drive rear hub. Maybe you mentioned that. I admit it. I'm late to this thread and haven't read all the prior posts. But you could help us out by being more precise: "I like the low end when using the 30T chainring". And which ratio on the DD? If its the low speed those are some truly low gears indeed. Or maybe you are in the smaller teeth (crosschaining?). I don't know... anything is possible but stupendously low gears on a bicycle can be impractical simply for balance reasons. I have trouble believing you could not get by with your present setup, it is already more gear range than most (two wheel) bikes will ever have.

In your situation I would: Buy the wife the Deore crankset I linked to or similar and the Deore FD to go with it. Take her 105 FD and her crankset. Call it very good. The only reason to change the 30T granny to a 24T would be if you didn't already have an IGH in the rear hub with a 75% reduction. But you do, so I'm not sure of why you want to do this.
We have recumbent trikes, for among several reasons, to eliminate any tipping concerns at slow / low-gear climbing. also, I never cross chain ! And what is Ďtotal chain wrapí ? Also, to be clear, yes, I like the low end with the 30t with the IGS low settting.

So, youíre concluding what I pretty much planned to go with initially. The only change I considered was going lower than 30t to get really low, if needed, with a touring load.

So, to conclude; get my wife a 48-36-26 (or more likely a 44-32-22...) and matching FD for her trike. On my trike, dump the Tiagra 52-42-30 and XTR FD, and use her 105 50-39-30 and FD. Swap the 30t with something smaller, even with the IGS. Now, perhaps keep the 30t ring and change the cogset from 11x32 to 11x34 to go lower ??? How about that idea ? Seems sound to me, but iím no guru....

Last edited by adablduya; 03-14-18 at 03:35 PM.
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Old 03-14-18, 03:55 PM
  #22  
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Originally Posted by adablduya View Post
So, to conclude; get my wife a 48-36-26 (or more likely a 44-32-22...) and matching FD for her trike. On my trike, dump the Tiagra 52-42-30 and XTR FD, and use her 105 50-39-30 and FD. Swap the 30t with something smaller, even with the IGS. Now, perhaps keep the 30t ring and change the cogset from 11x32 to 11x34 to go lower ??? How about that idea ? Seems sound to me, but iím no guru....
Granny rings can be very cheap, no pins, no ramps. More money gets you a better grade of aluminum (stronger). You can get them in the teens of dollars from somewhere like Dimension or FSA, in the low 20's from Salsa. A cassette otoh.. I have to think you are in for much more spent and for what, two teeth? That is half a gear in that range of tooth count. And I'm all for geeking out on the mechanics of it but changing individual cogs of a cassette is just not something I suspect you are prepared to do. So. Granny ring swap it is. FWIW. Total wrap is simply the complete front range and the complete rear range together. The rear derailleur has to wrap all the excess chain when you are in the small front and the small rear. BTW cross-chaining on most recumbents is a non-issue because of the very long chain run. It isn't a 'best practice', but I do it all the time. I didn't know you were riding a recumbent.
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Old 03-14-18, 09:53 PM
  #23  
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Originally Posted by adablduya View Post
We have recumbent trikes, for among several reasons, to eliminate any tipping concerns at slow / low-gear climbing. also, I never cross chain ! And what is ‘total chain wrap’ ? Also, to be clear, yes, I like the low end with the 30t with the IGS low settting.

So, you’re concluding what I pretty much planned to go with initially. The only change I considered was going lower than 30t to get really low, if needed, with a touring load.

So, to conclude; get my wife a 48-36-26 (or more likely a 44-32-22...) and matching FD for her trike. On my trike, dump the Tiagra 52-42-30 and XTR FD, and use her 105 50-39-30 and FD. Swap the 30t with something smaller, even with the IGS. Now, perhaps keep the 30t ring and change the cogset from 11x32 to 11x34 to go lower ??? How about that idea ? Seems sound to me, but i’m no guru....
"Total chain wrap" is the amount of chain the rear derailleur must absorb between the small chainring, small cog and large chainring, large cog combinations. Like this:
(large cog - small cog) + (large chainring - small chainring)
In the case of your wife's trike:
(34t - 11t) + (48t - 26t) = 45 teeth total wrap.

The reality is that you can fudge this some- most people don't use the small chainring and small cog combination, so if the chain hangs slack there it's tolerable. It just looks icky and can cause chain drops, especially with a trike's convoluted chain routing.

IMO, your original combination of large "road" chainrings and XTR derailleur is wonky. It needs front derailleur whose cage is shaped to fit the larger chainrings. If you have a 52-42-30 triple, you need a Shimano FD-R443 front derailleur. This is out of production, but some shops still have them. Consult with recumbent-oriented shops, like Hostel Shoppe. You don't want the newer FD-R453, which has a cage shaped for a 39-tooth middle chainring.

FWIW: I have a couple of the FD-R443 derailleurs on bikes in my garage: my wife's and my Gold Rush recumbents. Both bikes are set up with 24-42-52 cranksets and the FD-R443 derailleur shifts perfectly, even with index shifters.

Where are you? I'm familiar with most of the recumbent-oriented shops around the U.S. I may be able to point you at a helpful shop.
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