[pepckat]

hi, has anyone tried to change from a stock (shimano 105) compact 50-36, 170mm to a standard (shimano ultegra) compact 53-39, 172.5mm? what happened is, i found this Ultegra w/BB from competitive cyclist that they sold brand new for only $120 (this is the only size available), which i think they made a price mistake, last tuesday. it arrived thurs and had it installed friday. i know it was a good deal that i didnt want to pass on. i did a 40 mile ride today and had a bit of a hard time climbing the mountains. now my hips are aching a little. i am 5'6 with 29-inch inseam. is this crank ok for my height? if yes, do i just need to get used to a 53-39 from 50-36? need your opinions please....

 

[Pitts Pilot]

Well - you changed your gearing such that your lowest gear is not as low as it was before. This is more likely the culprit than the slightly increased crank length, although someone of your height probably didn't need to be lengthening their cranks. I don't mean to rub salt in any wounds, but going through the trouble to "upgrade" from a 105 compact to an Ultegra Standard is a questionable choice. Much more important is whether you want/need a compact vs. a standard crankset. I don't know enough about your ride today to comment, but if you spent a bunch of time in your lowest gear and it was not as low as the lowest gear you normally have and your hips hurt - yeah, maybe it's the problem. That said, maybe today was just a bigger ride than you normally do, as you were eager to try out the new stuff - kinda hard to know. Some days I hurt more than others for no apparent reason at all. (Getting old sucks.)

Spin to Win!

 

[SystemShock]

+1 to Pitt's take on it.

Given your height and inseam, 172.5mm is a bit of a long crank for you, yes. But the increase in gearing probably played a part in your aches and pains too.

You may be able to adapt to the new crank length and gearing in time, but whether or not it's optimal for you is something only you, with some more time and experience with the new setup, can truly say.

Also, don't buy stuff 'cuz 'its a good deal'... buy it because it's right for you, your build, and your riding style.

The guy who buys a $10,000 top-of-the-line super-uber-bike for $5000 is still a fool if the bike doesn't fit him, for example.

 

[locustfist]

All good thoughts.

You got such a good deal on it, you could sell it for that or maybe a bit more on Craigslist.

I gather that predominant opinion around RBR is that, unless you are planning on racing, a standard crank is un-necessary.

 

[pepckat]

ok, i'll give a couple of more rides and return or sell it. good that i still kept my 105, maybe it was not a good deal anyway. thanks for the suggestions guys!

 

[cxwrench]

ok, i'll give a couple of more rides and return or sell it. good that i still kept my 105, maybe it was not a good deal anyway. thanks for the suggestions guys!

return it? do the right thing and sell it. returning 'used' parts is lame, especially when you blew it by buying it.

 

[Randy99CL]

Did you remember to lower your saddle to compensate for the longer crankarms? If you didn't it is possible that you are rocking your hips now, may have cause the pain?

Longer crankarms require a larger range of motion that may take some getting used to; at the top of the stroke your foot is 5mm higher than before. Not a lot but enough to make a difference.

Don't forget that you are now 2.5mm more likely to scrape the arms when you pedal through a corner.

I agree with the others that for most of us big rings aren't really better than compact. A 50-11 is a little bit bigger gear than 53-12 anyway and since you didn't say you changed your cassette then you're probably riding a 53-11 big gear and that is pro level.
To get closer to the gearing you had before you need a bigger large cog on the cassette and if you already have an 11-28 you're now into mountain bike range and probably have to change your RD.
And weight-wise you're going in the wrong direction. Longer arms, bigger rings, bigger cassette and long cage derailleurs (at the same level) all weight more than compact.

Having said all that, my opinion is that 172.5 is too long for you. I am 5'8", 30" and like 170 and would like to try a 167.5 or even 165. There are lots of good articles on the net discussing crank length and I think that most people will recommend you go back to the 170s.
Final edit: I ride close to the same size frame as you and I doubt that any manufacturers put 172.5s on that small a frame. They can't all be wrong.

 

[pepckat]

agree and thank you. i would just go back to 170mm 50-34 and just sell the Ultegra. maybe the 120-gram shaving would not justify this. i was just so happy when my bike weighed 16.4 lbs total after the upgrade. i changed my chain too so i spent $200 total including installation. i would probably just put my 105 back or maybe look for a used ultegra or an FSA light to maintain my bike's weight.

 

[mikerp]

Longer crankarms require a larger range of motion that may take some getting used to; at the top of the stroke your foot is 5mm higher than before. Not a lot but enough to make a difference.

In this case he is 2.5mm higher.

In general this wasn't a good buy for the OP as he isn't in the "inseam" bracket to make use of longer cranks.

 

[Kerry Irons]

hi, has anyone tried to change from a stock (shimano 105) compact 50-36, 170mm to a standard (shimano ultegra) compact 53-39, 172.5mm? what happened is, i found this Ultegra w/BB from competitive cyclist that they sold brand new for only $120 (this is the only size available), which i think they made a price mistake, last tuesday. it arrived thurs and had it installed friday. i know it was a good deal that i didnt want to pass on. i did a 40 mile ride today and had a bit of a hard time climbing the mountains. now my hips are aching a little. i am 5'6 with 29-inch inseam. is this crank ok for my height? if yes, do i just need to get used to a 53-39 from 50-36? need your opinions please....

Pitts Pilot gave you the best answer except the bit about the cranks being "too long" for you. There is no credible evidence for crank lenght correlating to anything. Our bodies adapt and crank length preference is just that. The only thing you can say with some certainty is that shorter cranks encourage you to spin a little more since it's all about foot speed. Some people tell you that 2.5 mm is really significant while others say they can't tell the difference. If you keep these cranks you definitely should lower your saddle a bit to compensate for that 2.5 mm greater distance to the bottom of the pedal stroke.

 

[pepckat]

oh. this gives me a little hope... wait, i just adjusted my saddle higher. now youre saying that it should be lower. i'll do that and ride tomorrow. my hips are ok now, prbobably it was just one of those tiring rides, crank teeth adjustment and getting old. my cassette is 11-28 i think. also i signed up for gran fondo d'italia here in pasadena, ca on june2. i think there's a 4600ft climb on the course. im not racing anyone but myself. it would be a challenge for me and my 39 year old body. it will be my first event, any advise from an expert? thank you so much!

 

[Randy99CL]

In this case he is 2.5mm higher.

In general this wasn't a good buy for the OP as he isn't in the "inseam" bracket to make use of longer cranks.

Once he lowers his seat 2.5mm, his foot will be rising to 5mm higher than he's used to.

 

[Randy99CL]

I just ordered the FSA Energy Compact cranket from Nashbar last week.
The usual price is $129.99 but I got it on sale for $100 (retail is $275).

Energy has FSA's best (hollow forged) aluminum crankarms and it comes with the external bearing MegoEXO bottom bracket.

Everything I've read and heard about it has been positive.

Weight is right around 700gm with another 100gm for the BB; that is lighter than some cranksets with carbon arms.
I'll actually remove over a pound by replacing the crankset (with steel rings) that came on my bike.

 

[mann2]

Two things:

1. If you're into climbing mountains, yep, revert to the compacts. You're not gonna be a happy camper after grinding a 39T crank up something steep.

2. the 170 vs. 172.5 debate(or 172.5 vs 175 for that matter), has been going on forever and still there's no solid conclusion on its effects or lack thereof as a lot of people swear to both sides of the argument. Belonging to the 170mm tribe and having used the 172.5's for a limited time, i can definitely say that it's definitely a change for the better to get the right sized crankarms. That said, the 172.5 cranks were still pretty much rideable.

 

[pepckat]

Yes, I will train a little bit with the 39T to gain more power and switch back to 34T later on. Thanks for the input!

 

[Kerry Irons]

it would be a challenge for me and my 39 year old body. it will be my first event, any advise from an expert? thank you so much!

You'll get no sympathy here for your 39 year old body. Some of us have been riding since a decade before you were born.

As with any challenging ride the advice is the same: pace yourself, hydrate well, keep your electrolytes topped up, and keep fueled.

 

[pepckat]

thanks for the great advise! btw, asking for sympathy? all i said is: "it will be a challenge for me and my 39-year old body", meaning I'm challenging myself. if i said "my 18-year old body" would it have a different approach? just saying...