Compact Cranks

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Compact Cranks

Postby DavidH » Thu Dec 20, 2007 10:11 pm

Is there anyone on this forum that is currently using a compact (50/34) crankset? And more importantly, is there anyone that can share their experience with replacing a 53/39 crankset with a compact crankset?

I have two road bikes, both running 53/39 cranks, but one has an 11-23 cassette and the other a 12-25 cassette. If I'm heading off on a ride that involves any difficult climbing (e.g. 10% or higher gradient) I will ALWAYS use the bike with the 12-25 cassette since I prefer to climb with a higher cadence (and hey...it's just easier to climb with the smaller gear).

Now the bike with the 11-23 cassette has a worn out bottom bracket, and the chainrings have seen better days (while the chain and cassette are less than a year old). I'm going to replace the BB anyway, but at the same time I could move to compact cranks which would give me a higher high gear and a lower low gear than the other bike.

Sounds nice in theory, but firstly, would the existing FD work (and I mean work well) with the compact cranks?

My other concern is hard to describe, but I guess it's about the "ideal chain line". I've been riding this bike for years and I know which are my best cruising gears, and which combination of gears are best to minimise "cross chaining". For example, I cruise a lot in 39-15 which puts the chain smack in the middle of the cassette. If I were to use a compact crank this would be a similar gear to either 34-13 or 50-19, but would require a more indirect chain line in both cases.

I sent a lengthy email to my trusty LBS guy hoping for some advice...he sent a one line reply..."bring in the bike and I'll take a look". I'm going to take it to him on Sat but in the meantime I'd love to hear from anyone who has had practical experience with compact cranks.
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by BNA » Thu Dec 20, 2007 10:44 pm

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Postby sogood » Thu Dec 20, 2007 10:44 pm

I've been running a CT setup on one of my bikes since the middle of the year and will be converting my other one to CT soon (parts are in the mail).

A few issues,

1) Most likely your FD isn't CT compatible as regular FDs aren't designed for a 16 teeth drop. Yet again, I understand there are people who just live with it. Not sure about Shimano and SRAM, but Campagnolo has just this year brought out a combo FD that can handle both regular and CT chainsets. Fortunately, FDs aren't too expensive (see PBK).

2) I wouldn't worry too much about the chain line with modern 10 speed setup. With 10 speed chains, it's more flexible and can accommodate the varying chain angle better. As for wear, the difference is not that significant. So don't worry about it unless you hear the grind.

3) CT will give you two extra lower gears for the same cassette but you'll also lose some at the top. Top end loss can be resolved with a 11-25 cassette.
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Re: Compact Cranks

Postby thomas_cho » Fri Dec 21, 2007 6:43 am

DavidH wrote:Is there anyone on this forum that is currently using a compact (50/34) crankset? And more importantly, is there anyone that can share their experience with replacing a 53/39 crankset with a compact crankset?

I have two road bikes, both running 53/39 cranks, but one has an 11-23 cassette and the other a 12-25 cassette. If I'm heading off on a ride that involves any difficult climbing (e.g. 10% or higher gradient) I will ALWAYS use the bike with the 12-25 cassette since I prefer to climb with a higher cadence (and hey...it's just easier to climb with the smaller gear).

Now the bike with the 11-23 cassette has a worn out bottom bracket, and the chainrings have seen better days (while the chain and cassette are less than a year old). I'm going to replace the BB anyway, but at the same time I could move to compact cranks which would give me a higher high gear and a lower low gear than the other bike.

Sounds nice in theory, but firstly, would the existing FD work (and I mean work well) with the compact cranks?


Shimano does not have a dedicated compact cranks FD. So your existing one will work. You might have to shorten your chain a bit as well.

If you are getting the compact crank with external bearings, the bottom bracket (on the frame) needs to be flush to allow the bearings to fit squarely. Chances are they would be .. but you should check it out with the bike shop.

I have been swapping my cranksets around, and external bearing cranks are very easy to fit and remove.
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Postby DavidH » Fri Dec 21, 2007 8:45 am

sogood wrote:Most likely your FD isn't CT compatible as regular FDs aren't designed for a 16 teeth drop

I've read conflicting reports on this one and this will be one of the main issues I raise with the LBS. But as you say, FDs aren't overly expensive and if it needs to be replaced then so be it.

sogood wrote:I wouldn't worry too much about the chain line with modern 10 speed setup

Good advice...except that the bike I'm converting is Dura-Ace 9-speed :D (the groupset is about 5 years old, which includes octalink BB and cranks). In any case, I'm still not sure that my chain line concerns are warranted.

sogood wrote:CT will give you two extra lower gears for the same cassette but you'll also lose some at the top

I can live with losing some at the top (but it will still have a bigger top gear than my 53/39 & 12/25 setup on my other bike, which was a surprise to me when I did the calculations).

sogood wrote:...and will be converting my other one to CT soon

I explained to my wife (who rides too) that the CT conversion will be the last modification for a while. She just rolled her eyes and said that if it works out then I would probably convert the other bike as well. She knows me too well.

thomas_cho wrote:Shimano does not have a dedicated compact cranks FD. So your existing one will work

This is the impression I get from my Google searches on this topic. Fingers crossed then!

thomas_cho wrote:If you are getting the compact crank with external bearings

It doesn't currently have external bearings since it's an older 9-speed groupset, and I will most likely replace the BB with a similar octalink style BB.

Thanks for the feedback. I'm still in the "will I or won't I?" stage.
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Postby sogood » Fri Dec 21, 2007 9:18 am

DavidH wrote:I can live with losing some at the top (but it will still have a bigger top gear than my 53/39 & 12/25 setup on my other bike, which was a surprise to me when I did the calculations).

How can that be possible if the cassette is unchanged? If you pair CT with 11-xx cassette, then yes, it'll have higher gears than regular with 12-xx.
I explained to my wife (who rides too) that the CT conversion will be the last modification for a while. She just rolled her eyes and said that if it works out then I would probably convert the other bike as well. She knows me too well.

I am fortunate in this department as I just bought my wife a frame of her own for BD and Christmas. I'll use the present triple on her new bike and swap in a new CT setup for mine. This way she's happy and I'll be happy too. :)
thomas_cho wrote:Shimano does not have a dedicated compact cranks FD. So your existing one will work

This is the impression I get from my Google searches on this topic. Fingers crossed then!

I stand corrected on this issue. Didn't know Shimano had a universal FD.

I think the key issue is whether you are keen to experiment. I argued and schemed before my first CT too and only got a true feel for the setup after I've used it and fortunately, I am happy with it. The other issue that one should point out is the bigger drop and less overlap b/n the gears provided by the two chainrings. Typically I need to drop 4 cogs or more for chainring change. This may irritate some people but is something that one can anticipate and adapt to.
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Postby MichaelB » Fri Dec 21, 2007 10:14 am

My bike (LeMond Torumalet) runs a semi-compact set. It came witha 39/50 & 12-25 for a 105 9sp Groupset.

To aid in hill climbing, I fitted a 38T inner chainring, and have a 12-26 cassette on the other set of wheels. This gets me though most things within my capability at the moment, but not any hills with seriously long or steep climbs.

My chiro just recently changed to a ompact Campag setup (Record) as he loves climbing hills, but he is mad.

In changing to a compact setup, do you not have to look at the capacity overall with the RD as well ?

How many teeth can a typical short cage RD cope with ?


Oh, and how do you get from a Copact Crankset to CT ?
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Postby sogood » Fri Dec 21, 2007 10:27 am

MichaelB wrote:My chiro just recently changed to a ompact Campag setup (Record) as he loves climbing hills, but he is mad.

Mad about changing to CT or his love of hill? Or just plain mad? :shock:
In changing to a compact setup, do you not have to look at the capacity overall with the RD as well ?

Yes you do and I remember looking this info up recently for a fellow forum member. With Campag's setup, a short RD paired with regular or CT chainset can cope with any cassette below 13-29. So I suspect that pretty much covers everything that's in common use. Check Shimano and SRAM, I suspect they are similar.
Oh, and how do you get from a Copact Crankset to CT ?

CT is compact.
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Postby MichaelB » Fri Dec 21, 2007 10:34 am

sogood wrote:
MichaelB wrote:My chiro just recently changed to a ompact Campag setup (Record) as he loves climbing hills, but he is mad.


Mad about hills. Loves things like 15% + gradient. He is a bit nuts as well in general .... :lol:
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Postby DavidH » Fri Dec 21, 2007 10:51 am

sogood wrote:I think the key issue is whether you are keen to experiment. I argued and schemed before my first CT too and only got a true feel for the setup after I've used it and fortunately, I am happy with it. The other issue that one should point out is the bigger drop and less overlap b/n the gears provided by the two chainrings. Typically I need to drop 4 cogs or more for chainring change. This may irritate some people but is something that one can anticipate and adapt to.


Keen to experiment, but not to keen to spend $$ on a failed experiment :roll:

Good point about the smaller overlap and having to anticipate chainring changes with a greater number of rear cog changes.

Hmmmmm <- me mulling it all over in my head :?
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Postby sogood » Fri Dec 21, 2007 11:00 am

DavidH wrote:Keen to experiment, but not to keen to spend $$ on a failed experiment :roll:

Good point about the smaller overlap and having to anticipate chainring changes with a greater number of rear cog changes.

Hmmmmm <- me mulling it all over in my head :?

Bad isn't it? It's all about experimentation and tuition fees. At least there's some technical numbers you can go by with chainring selection. With saddles, that's a real wild guess.

Anyway, I picked up a new alloy Campag Centaur CT chainset from PBK for around $170. Not too bad given a new cassette may come close to that or more. Worse comes to worse, you can always eBay it off.
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Compact conversion

Postby wayno » Sat Dec 22, 2007 7:37 am

Hi all,

I just bought a new Shimano R600 compact crank on ebay for $110 delivered, a little bit more expensive than a new 10 speed cassette but a good price. I'm just going to give it a go over this holiday break.

Unlike other compact cranks it is ok to use standard front deraillleur, it will have be lowered though, Shimano have excellent installation instructions.

I will also change my cassette from 12-25 to 11-23....I think this will be perfect for me.....bring on those big hills.

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Postby DavidH » Sat Dec 22, 2007 2:21 pm

wayno wrote:I just bought a new Shimano R600 compact crank on ebay for $110 delivered, a little bit more expensive than a new 10 speed cassette but a good price. I'm just going to give it a go over this holiday break.

I'm looking forward to hearing about your experiences with the new cranks. If it's a 50/34 crankset then I think your decision to change the cassette to an 11-23 is a good one.

I took my bike to the LBS guy today to get his opinion on moving to a compact crank. He thinks it's a good plan and is confident that my existing FD should be fine. His only advice was to buy the cranks first and bring them in to the LBS with the bike. That we he can install them on the existing BB, check the setup, and based on the results ensure that the appropriate new BB is purchased. He believes that chain line issues (if they arise) can sometimes be resolved by getting a BB in a specific width. Makes sense to me, but the downside is that I was planning to buy the parts from PBK which would mean paying for postage twice. I'll need to do some more shopping around to determine the most cost effective way of getting the "bits".
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Postby thomas_cho » Sat Dec 22, 2007 2:30 pm

I think you are worrying too much about chainline. Shimano have designed their compact cranks to work successfully with their existing FD. I think FSA ones required a specific FSA FD to work properly.

There could be a potential issue tho ... if your frame requires a braze on FD, it could restrict the proper positioning of the deraileur, as in you may not be able to move the derailleur down enuf. Having said that I have build up an old bike (mid 80's) with a current day compact crankset, and did not have a problem with the FD shifting.

Also the R600 uses a external bearing system. Provided you have this on your bike already, there is no way to "try it" as your LBS suggested.
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Postby DavidH » Sat Dec 22, 2007 4:21 pm

thomas_cho wrote:I think you are worrying too much about chainline

I suspect you're right. Time will tell. :D

thomas_cho wrote:Also the R600 uses a external bearing system. Provided you have this on your bike already, there is no way to "try it" as your LBS suggested.

No, it's an old Dura-Ace 9-speed groupset so it's not an external bearing system. I don't see any problem with the LBS guy removing the existing cranks and popping the new ones on.

I had planned on buying a Ritchey Pro Road V Crank Chainset from PBK. With shipping it comes to a total of $165.06. I took a quick look at Chain Reaction Cycles (which I normally avoid since their shipping costs are so high) and they have the same cranks on sale. Even with their crazy shipping costs it's $144.35. Cheapest so far.
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Postby thomas_cho » Sat Dec 22, 2007 10:18 pm

If you are keeping to Octalink then its not a problem to try.

I guess my point was since you are going to change out the BB as well ... it might be worth considering the new crankset with the external bearing cups. They are supposed to be a better more durable design.
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Postby wayno » Mon Dec 24, 2007 10:26 pm

David,

I think my 10-Speed conversion is fairly simple. I do have to wait for my bits from Ebay though. Have you tried searching in ebay for the crank?
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Postby DavidH » Tue Jan 08, 2008 8:43 pm

My Ritchey Pro Road V Crank Chainset (50/34) arrived yesterday and I've just finished putting it on the bike (using the existing BB). Will have to wait till tomorrow for a test ride (sadly) but have a few points worth noting so far.

After ordering the cranks I took a close look at the service manual :roll: for the front derailleur and it says that it should be used with a crankset of 15 teeth difference or less. The 50/34 compact cranks have a 16 teeth difference, but it seems to work OK with the bike on a bike stand. It's a brazed-on and I had to move it to the lowest possible position which places it about 3mm above the biggest chain ring, which is fine.

I also had to remove a couple of links out of the chain, which was no drama as I'm using a Wipperman Connex link on a Shimano chain.

I'll take it for a short ride the morning and see whether it was money well spent (or whether the Ritchey Cranks are the first components on my next project bike :lol: ).
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Postby wayno » Tue Jan 08, 2008 9:23 pm

Hi DavidH,

I received my tools today for my compact conversion. Being a Shimano Hollowtech II BB it was really easy, only took 1.5hr. Remove the old crank, grease the new and tighten screws...thats it. I didn't have a torque wrench though but have one coming soon.

Other bits I had to do were, lower the front derailleur, retension and take off 2 links (52-50=2). I'll adjust the front and rear derailleurs tomorrow on the workstand (a piece of rope hanging on the garage rafters which I hang my seat on).

I can't believe how easy it was. My only regret is not getting the Ultegra SL compact crank as the silver R600 stands out like dogs balls. Also beware the R600 crank weighs 850g!!!! Even a 105 crank (52-39) weighs in at only 750g.

Bring on those big hills
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Postby wayno » Tue Jan 08, 2008 9:29 pm

Oh my only concern is that I re-used the shimano pin. Should I be worried?
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Postby DavidH » Tue Jan 08, 2008 9:40 pm

Hi wayno,

Where did you order your torque wrench from? It's on my wish list :)

Replacing the Octalink cranks on my bike was a bit more of an ordeal. It's a long story, but I had some "issues" removing the old cranks (mainly due to over tightening on my part...hence the need for a torque wrench!).

The Ritchey cranks are black and my bike is black, which is a bonus. But I seem to recall that you got your cranks at a bargain price on Ebay so I wouldn't worry too much about the "look".

I'm pretty sure you're not supposed to reuse Shimano chain pins so I'd keep an eye on that one.

Looking forward to swapping tales of our first compact crank rides!

David
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Postby Mulger bill » Tue Jan 08, 2008 10:01 pm

wayno wrote:Oh my only concern is that I re-used the shimano pin. Should I be worried?


Not recommended by Shamino. Their pins have flared ends and widen the hole fractionally when pushed out. Replace that pin and link with a SRAM or Connex link and it's all good...... assuming you can find it again... :wink:

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Postby wayno » Tue Jan 08, 2008 10:23 pm

I have a brand new SRAM chain sitting on my desk but wanted to re-use the 'old' (1 month old) chain.

Its easy to tell which was the connector pin on Shimano, its the only full solid pin, the others have a routed circle on them. The pin is in pretty firm, I know the standard pins cannot be used as the flange snaps off but I think the connector pin is ok. Hey its only a disconnected chain...right!!
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Postby Bnej » Wed Jan 09, 2008 8:01 am

wayno wrote:...The pin is in pretty firm, I know the standard pins cannot be used as the flange snaps off but I think the connector pin is ok. Hey its only a disconnected chain...right!!


You're not supposed to reuse that either, as pushing connector pins through the same link multiple times damages the link and can lead to breaking the chain - the connector pins are harder and will bend the side plates as you push it out.

You're meant break the chain on a new link each time and then push a new connecting pin through (couple of dollars from your LBS). If you're removing it often you should use a powerlink or similar.
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Postby wayno » Wed Jan 09, 2008 9:42 am

Bnej wrote:You're meant break the chain on a new link each time and then push a new connecting pin through (couple of dollars from your LBS). If you're removing it often you should use a powerlink or similar.


Thanks for that Bnej, I was following T7 maintenance tips (bad move hey), I'll run up to my LBS today or use my new sram link
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Postby DavidH » Wed Jan 09, 2008 6:11 pm

Had my first ride with the compact cranks...up and down the road in front of my house. Surprisingly I didn't have to make any further adjustments to the FD and it shifts as well as the old 53/39 cranks :D

So far, so good.

I have an early morning ride tomorrow with a few other riders so it will get the full workout then.
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