19 January 2009

Everything you always wanted to know about compact cranks. Or perhaps not.

One of the recent posts on this blog about the pros and cons of standard and compact cranks really hit me. I started to think day and night about cranks and I could barely sleep, drink, eat or ride my bike, activities which are said to be the mission of the Positivo Espresso team. In case you forgot, please look at the backside of your team jersey.

Lately I have been attested to have only "decent knowledge of bicycles" by an the Japanese outpost of a large US bicycle company, which name is similar to the German word DRECK. So before making any further statements about compact cranks and which one to buy, I did a long research on the web which lasted until today. Probably there are many things you know already, but perhaps there is the one or other guy out there with the same poor level of bicycle technology level as I have.


The reasonable choice : Shimano Ultegra SL FC-6650-G
Yes Shimano, which is not really considered cool because everybody has them, but otherwise everybody would agree that most of the products they are doing are of very good quality and durability and reasonably priced. In particular if you don't buy them in Japan. Also the Ultegra design is in my viewpoint good, much better than the bulky Dura Ace design which I really, really dislike. And do you hear often of quality issues or product recall with Shimano components? And you can get spareparts everywhere in Japan on short notice- try this with Champagnolo or Side (my experiences).

This one is all aluminium but has a hollow crank which helps to reduce weight to 808gr, including bottom bracket. This compares to around 650 gr for more expensive products without bottom bracket weight. No need to resort to carbon here.

One can have different crank arm length between 165 and 175 mm, but chainrings are available only in 50/34. But this should be OK. The BOD [bolt cicrle diameter] is 110 mm (standard crank 130 mm) so you should be able to use chainrings of other makers as well.

Is designed for a bottom bracket of 68/70 mm with English threads - the standard we all have. And can be bought for example here for 161 Euro / 20.000 JPY which is very reasonable indeed.

So enough talked, I went to Nagai-San's shop this week and ordered one to replace my Lehman-Force, sorry SRAM Force standard crank.

The Carbon One : FSA SL-K Light Compact Road
Apart from the usual suspects Shimano, Campagnolo and SRAM, FSA has a very wide range of cranks in their product portfolio, road compact cranks alone account for 8 types.

This one is already on the bikes of Ludwig and Bryon mounted and so far experiences have been good. Although the outside of the crank is carbon and it is described as "hollow" is it not: There is an internal I beam (made of aluminium?) inside, providing the required strength and stiffness.

Thus the weight with bottom bracket is 780 gr, not too much lighter than the much more cost competitive Ultegra. But the design looks good with the carbon crank which is available with length between 170 and 180 mm.

For a carbon fork the price tag of 455 Euro / 57.000 JPY is in the middle of the competition, being more expensive than a Shimano Dura Ace (not Carbon) and in the same class as a Campagnolo Record.

There are not so many infos on the FSA site about other techical specifications. It seems that you can also use this crank with a bottom bracket of ceramic bearings of which Bryon was much impressed.

Let's spend heaps of money : THM Clavicula
THM is a German manufacturer of high performance carbon components. This crank called Clavicula (I guess it means collor bone) weights only 410 gr, of course without the chain rings which needs to be purchased separately (BCD 110 mm). Can be mounted an English threads bottom brackets 68 mm, cranks are available with 170 to 175 mm length.

It looks perfect, very sleek, question is if this is really needed.
Please dive deep into your pockets: 920 Euro / 115.000 JPY needs to be paid. Perhaps it would be better to buy another cheap bike with compact crank for this amount of money.

Apart from this, there are many other makes on the market for compact cranks, I list below the most interesting ones:
And it is also interesting to note that some makers do not sell their cranks any more, for example DEDA and Ritchey.
I summarized a lot of the information in an xls file, if you are interested to get it, please send me a quick note.


Manfred von Holstein said...

Good research. Sounds very convincing to me. I bought the crank set with the bike and without selecting anything other than its size, so wouldn't swear on FSA carbon as I have no comparison. Still amazed by the retail prices for these things. That's something like 15% of the price of an entire, expensive bike - for what is just one of so many components.

James said...

I know you've made your choice after much research and given that David has been using the same crank I am sure it is a good one. Just for info., you can pick up the FSA SLK Carbon Lite for Y34,000 (shipping incl.) from the UK. The benefits of a very weak British Pound.

TOM said...

The FSA SLK Carbon Lite is certainly attractive design-wise; I also like the looks of the Fulcrum compact. Have not been entirely happy with Campagnolo (Centaur compact) and FSA (Team Edition compact) though. On both cranksets, the outer chainwheel produced and unacceptable wobble to the point I busted 3 front derailleurs in the process (probably entirely due to my inability to keep the pedals turning in a smooth and fast way) and had to be replaced. I am now using Shimano 105 chainwheels on both cranksets and so far no wobble!