skids929

My whole bike has 105 with the exception of the crank. I notice the higher gear in the front gets a little dodgy and loud, which may just be an adjustment but caused me to think about it a little and the potential of changing out the FSA for Shimano. In addition if I changed the crank it would give me a full Shimano group which I think would look nicer as well. My question is:

1) would Shimano 105 be an improvement over the FSA Gossamer Pro?

2) would I have to switch out my bottom bracket or could I mount to the one I have

3) my current tooth config is 48/32, which I don't think Shimano has they have a 50/34 which is closest. Would this make a huge difference or would it be negligible.

Thanks for the advice!

DomaneS5

My Gravel bike is loaded with 105 components except for the crank which is a: FSA, Gossamer Compact 50x34T

I have the Shimano 105 crank on my Trek Domane...also 50x34. I can't tell much difference between the two. The Gossamer is most likely a few milligrams heavier and beefier for gravel use. Both are good cranks.

skids929

Good point..And I do use my bike for some light trails/gravel, didn't really think about it that way. But I do like the 105 matching and I love Shimano stuff, thought I'd turn it all into one group.

andr0id

As long as you have an English 68mm bottom bracket, you can easily convert it.

You can also use converters for most press fit BBs.

The Praxis converters are well reviewed and the people that have posted about them say they are solid and squeak free. That is because of how they expand when assembled.

There was a time when there seemed to be complaints about the FSA left crank getting loose. I have one on my tandem and have not had a problem, but I don't like the way they assemble very much.

mstateglfr 

What does 'a little dodgy and loud' mean? The crank really shouldnt make any noise...ever. At worst, the crank may make a clicking noise which is usually a chainring needing to be tighter.
Other clicking noises can be the bottom bracket not secure or something within the pedal release mechanism(i assume you use SPD or similar).

The crank is really just a piece of metal on either side of the bike...not much there to make noise or be 'dodgy'.



32t vs 34t could be noticed if in the largest cog. I say this based on my knowing there is a difference between my old 36t inner ring and my current 34t inner ring on one of my bikes. That 2t difference is noticeable on climbs when I am using the 36T cog in back.



The reason why FSA cranks are used on so many road bikes when Shimano is spec'd is because a lot of bikes us PF30 bottom brackets and Shimano cranks cant attach to PF30. An adapter is needed to use a Shimano crank.
my opinions follow-
- PF30 is absurd and serves no benefit for most all users.
- PF30 is more difficult to service compared to BSA threaded bottom brackets.

If you get a Shimano crank, you will need an adapter for the bottom bracket style. Just know that going in and do your homework.
...or figure out what is actually 'dodgy' about your current setup and tighten it.

skids929

Thanks...Yeah I agree I need to look at what adjustment it may need. I don't use the part of the crank as much so haven't been in a rush to do it.

I can't see what the BB is for this bike (has a gold cap if that helps), I need to call Specialized (it's a Sirrus Expert) to see what they put in there since they don't list it in their spec. I just assume replace it with an Ultegra BB if that is more compatible for the 105 crank, they don't seem too pricey. CORRECTION: they do list it in their spec it's a BB386 EVO.

I just thought maybe the 105 would be smoother overall and match into the rest of the components better than the FSA. but if this is a more fragile crank I may keep it as is. Not sure why Specialized doesn't use 105 and swaps in FSA components on alot of their models, I assume $$.

Scooty Puff Jr

Thats pretty much it, its all about cost vs profit.

skids929

yeah that figures. Seems to be mixed reviews on FSA, some love it some don't. I haven't had it ling enough to say one or the other. What I can say is that 105 shifts like butter, so for me I'd have no issue complimenting what I know is already awesome with the 105 crank. Even though yes it may not have huge impact.

They apparently make a CX version of that too which my LBS is suggesting for me since I do some gravel travel.

Marcus_Ti

The CX Shimano crank will have a higher (harder) low gear than the Ultegra compact.

Std compact: 50/34
CX: 46/36

Whereas you presently have a 48/32.


So the changes are that the Ultegra compact will have a slightly higher high and low gear....and the CX crank will have a much lower high, and much higher low gear.

If you want a 48/32, Praxis Works makes one that is very reasonably priced: https://www.praxiscycles.com/product/alba-m30/

skids929

Yeah I was thinking I could do just the chain rings with Praxis and install those, but this is a nice option too. I don't have experience with Praxis but safe to assume the quality is better than FSA? Or same?

mstateglfr 

I have a CX50 on my gravel bike mated to 105 derailleurs. $13 on ebay will get you an Ultegra 34t 5 hole chainring to drop the inner ring down.
46/34 gearing that way.

The crank is plenty light, stiff, and durable for my gravel riding. Best of all, its 5 arm still instead of the fuggo 4arm things they now sell.

skids929

Yeah sounds like a good idea..I have to decide if I will miss the 48. I do use, but not often unless I am cranking downhill and want to add speed, which I usually just rest or tuck instead of pedaling.

mstateglfr 

48x11 is 1.2mph faster than 46x11 when spinning at 80rpm. As you mention, its a rare day when the large ring and small cog are used for extended periods of time(or even short periods). Once you are on a hill, tuck and rest is a pretty common decision, so that little bit of extra gear isnt then needed.

Few in this world need 50/11(much less 48 or 46) when they(me included) arent then also spinning at 80 or 90rpm in that gearing for many minutes on end.