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Changing Crankset to a midcompact

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Changing Crankset to a midcompact

Old 06-07-17, 01:59 PM
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Boondocksaints
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Changing Crankset to a midcompact

Hello people,

I am very close to ordering a bikes direct Titanium bike that comes with Ultegra 6800 parts, except for the crankset which is a Compact Double 50x34T FSA.

I have decided I want a matching Ultegra crankset instead so will order that. However, I want a semi-compact (Mid-Compact) 52/36 crankset instead.

My question is this: Do I need to also get a matching Ultegra bottom bracket or can I keep the FSA one that comes with the bike.

Secondly, do I also need to get another chain since I am changing from a 50x34 Compact to a 52/36 Semi-Compact crank.

And finally, would I need to change the derailleurs?

Any help or advice is greatly appreciated. I don't want to order a $200 crankset and then I can't use it. Thanks in advance!


Below are the specs of the bike I am ordering (and which I want to replace with a mid-compact Ultegra crank)

Crankset - FSA N11, Gossamer Compact 50x34T, HG C-Ring , W/ ALLOY BLK ANOD. CTL Crank 170/172.5/175mm for 50-53/55/58-61CM

Bottom Bracket - FSA BB-6200 MEGA EXO BB (68mm)

Front Derailleur - SHIMANO FD-6800 ULTEGRA FOR FRONT DOUBLE & REAR 11-SP BAND TYPE(31.8MM)

Rear Derailleur - SHIMANO RD-6800, ULTEGRA GS 11-SP, COMPATIBLE 28-32T FOR DOUBLE

Shifters - SHIMANO SHIFT/BRAKE LEVER, ST-6800, ULTEGRA

Cassette/Freewheel
- SHIMANO CASSETTE, CS-6800, ULTEGRA, 11-S, 11-12-13-14-16-18-20-22-25-28-32T

Chain - SHIMANO BICYCLE CHAIN CN-HG701-11, FOR 11-SPEED

Last edited by Boondocksaints; 06-07-17 at 03:33 PM.
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Old 06-07-17, 02:59 PM
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trailflow1
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The FSA BB would not be compatible with 6800. You'll need to remove (unscrew) the FSA megaexo BB and fit any Shimano Hollowtech 2 BB (Tiagra,105,Ultegra,Dura Ace) to work with the 6800 crank.

The chain might not need changing either. It all depends how much it was shortened when it was installed. Alot of times, factory bikes come with chains that are too long. So you might be good. I would try it first. Before spending money. If the chain is too short. Only the big/big combo would likely be unusable. That combo is easily avoided. Even if its temporary until you buy a new chain.

All the others parts will work fine. They do not need changing.

The FD may need to be re-positioned higher to clear the 52t chainring.

Last edited by trailflow1; 06-07-17 at 03:05 PM.
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Old 06-07-17, 03:34 PM
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Boondocksaints
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Originally Posted by trailflow1 View Post
The FSA BB would not be compatible with 6800. You'll need to remove (unscrew) the FSA megaexo BB and fit any Shimano Hollowtech 2 BB (Tiagra,105,Ultegra,Dura Ace) to work with the 6800 crank.

The chain might not need changing either. It all depends how much it was shortened when it was installed. Alot of times, factory bikes come with chains that are too long. So you might be good. I would try it first. Before spending money. If the chain is too short. Only the big/big combo would likely be unusable. That combo is easily avoided. Even if its temporary until you buy a new chain.

All the others parts will work fine. They do not need changing.

The FD may need to be re-positioned higher to clear the 52t chainring.
Thank you!

What do you mean by "big-big" combo though?
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Old 06-07-17, 04:41 PM
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Big/Big means using the big chainring in combination with the big cog on the cassette (cross chaining). When doing so, the chain is at an extreme angle and the RD cage will be at its maximum extension. If the chain is too short and the RD cage is fully extended and cannot spring back. Spinning the cranks in this combo will tighten up the drivetrain/chain and it will make alot more noise, worst case scenario it will lock up the drivetrain or at least make the chain hard to turn. That's how you will know the chain is too short. So it's best to check it while in the workstand beforehand. Not out on the road.

Big/big is not a combo that should ever be used for long periods. or ever if yuou can help it. Because it causes premature wear of the chain. And it is the noisiest gear combo.

But the chain still needs to be the correct length if you ever do click into that combo by accident.

Last edited by trailflow1; 06-07-17 at 05:32 PM.
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Old 06-07-17, 04:46 PM
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Originally Posted by trailflow1 View Post
The FSA BB would not be compatible with 6800. You'll need to remove (unscrew) the FSA megaexo BB and fit any Shimano Hollowtech 2 BB (Tiagra,105,Ultegra,Dura Ace) to work with the 6800 crank.

The chain might not need changing either. It all depends how much it was shortened when it was installed. Alot of times, factory bikes come with chains that are too long. So you might be good. I would try it first. Before spending money. If the chain is too short. Only the big/big combo would likely be unusable. That combo is easily avoided. Even if its temporary until you buy a new chain.

All the others parts will work fine. They do not need changing.

The FD may need to be re-positioned higher to clear the 52t chainring.
Not sure 'by the book' if one could determine how short the chain is if the original chain was sized correctly, but is it an option for the OP to get 2 or 3 quicklinks to extend his chain length?
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Old 06-07-17, 05:04 PM
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That's an option. Some people do that and get on fine, 1 Quick link will be fine but a 2nd i think would add another weak point to the chain. Quick link are not as strong as proper links and can fail sometimes. I've witness both KMC and Sram links do it. So you kinda increase the chances of link failure the more you add. That's just my view. I suppose it all depends how much you trust those extra quick links. If you were to do it. I wouldn't join two together at the same spot if two were needed. I'd put them a good distance from each other.

Trouble is, quick links can be expensive when bought separately. It can be more economical to buy a chain that includes a quick link.

Last edited by trailflow1; 06-07-17 at 05:23 PM.
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Old 06-07-17, 06:31 PM
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Originally Posted by trailflow1 View Post
That's an option. Some people do that and get on fine, 1 Quick link will be fine but a 2nd i think would add another weak point to the chain. Quick link are not as strong as proper links and can fail sometimes. I've witness both KMC and Sram links do it. So you kinda increase the chances of link failure the more you add. That's just my view. I suppose it all depends how much you trust those extra quick links. If you were to do it. I wouldn't join two together at the same spot if two were needed. I'd put them a good distance from each other.

Trouble is, quick links can be expensive when bought separately. It can be more economical to buy a chain that includes a quick link.
A 6-pack of 11s KMC missing links goes for about $15, so I guess it depends. Whatever happened to the old saying that a chain is only as strong as its weakest link? If you have 1 or 20 quick links making up the chain, isn't the chain just as strong (or weak) either way?
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Old 06-07-17, 07:02 PM
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Originally Posted by Sy Reene View Post
Not sure 'by the book' if one could determine how short the chain is if the original chain was sized correctly, but is it an option for the OP to get 2 or 3 quicklinks to extend his chain length?
Keep in mind that the difference between 50 and 52 teeth is one link and also that on any chainring only half the teeth are engaged with the chain so that amounts to one half link. Unless the chain was sized at its extreme limit, odds are very high that the chain is fine
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Old 06-07-17, 08:28 PM
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Originally Posted by Sy Reene View Post
A 6-pack of 11s KMC missing links goes for about $15, so I guess it depends.
I've never found the 11-speed links available for less than $6 each from US sellers. I've seen 4-packs from the UK/Asia for $20, if willing to wait a few weeks for them to arrive. Two fifty a link sounds pretty great.
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Old 06-07-17, 08:35 PM
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Originally Posted by DrIsotope View Post
I've never found the 11-speed links available for less than $6 each from US sellers. I've seen 4-packs from the UK/Asia for $20, if willing to wait a few weeks for them to arrive. Two fifty a link sounds pretty great.
hmm.. to be honest, I've only ever bought a 6-pack once, at the first link I found on Amazon. However, clicking back to the product on my order, it's showing as unavailable, and can't even find 11s 6-packs on Amazon (sold by any seller). 10s 6-packs available though at $14.

Anyway, it was actually $16 for 6.
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Old 06-07-17, 08:39 PM
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It must have been awhile ago, because 6-packs on Amazon and eBay are now around $30... unfortunately.
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Old 06-07-17, 09:09 PM
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Originally Posted by DrIsotope View Post
It must have been awhile ago, because 6-packs on Amazon and eBay are now around $30... unfortunately.
about a year ago (July, 2016).. even so, are 11sp links that much higher priced than 10 speed? A bit odd..
https://www.amazon.com/KMC-Missing-L...d+missing+link
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Old 06-07-17, 09:16 PM
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Yeah, it's definitely a kick in the ass. I got an early Father's Day gift-- upgrade to 11-speed. The parts themselves was around the same or even cheaper in some instances compared to my Shimano 10-speed group, but the price of quick-links from SRAM, KMC, and FSA are nuts. Even on Amazon, usually around 8 bucks apiece. Wipperman/Connex makes a reusable 11-speed link that goes for $25-30.

And as I just started experimenting with hot wax for my chain, I either need a line on cheaper quick links, or to knuckle down and buy the criminally-priced Wipperman.
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Old 06-08-17, 06:18 AM
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Originally Posted by trailflow1 View Post
Only the big/big combo would likely be unusable. That combo is easily avoided.
I would advise against ever running a too-short chain. If you forget and try to shift into that combination, and you will eventually, you can do serious damage to your drivetrain and possibly your frame, before you know it. Always test this by slowly turning the cranks by hand and carefully shifting; STOP if you start to strain anything and remedy the situation before riding the bike.
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