elcruxio

So I broke my bb30 gossamer crank yesterday.
Broke off the bolt shoulder (might have overtightened it a bit...) I did not think that cranks broke so easily, but apparently everything is possible.
Well, a new crankset is coming so I have a few questions.

Firstly the old crankset was a compact 48/34 so I ran out of gears when reaching 50km/h speeds. Then again the ratios were kinda nice on steep uphills, but where I live now there aren't too many of those.
The new crankset has a double 53/42. Am I in trouble? I mean can I expect to handle such high gear ratios (in time sure, but right now)?
Is there a possibility of me getting faster due to the bigger rings? I know it's a silly thought, but there might be some extra motivation to develop to achieve the standard 90rpm on the larger ring without crosschaining.

I checked and the apex FR I have should be able to handle both compact and standard doube. But I expect I have to raise the FD a bit and do some extra adjustments?

Now it's official. Due to the crankset switch this bike is no longer a CX in any way except the frame...
If only there were 1 inch larger wheels and tires... I could have a very cool large dude experiment with proportional wheels and components. But that's irrelevant.

Never getting anything with gossamer written on it again...

igknighted

Google for a gear-ratio calculator... going from a 34t to a 42t is a major change, expect to work a lot harder climbing. Frankly, I am amazed you found a BB30 crank with that gear ratio, that exceedingly uncommon these days. You could swap chainrings (trade the 42t for a 38t or 39t for example), or reconsider a different crank model (compact with 50/34 or 52/36 are most common now).

As for geting faster... in short, no. When the road gets steep, even the pros reach for smaller gears. You may see you muscles get bigger, but you would get faster quicker and with less chance of injury by keeping the gear in a range that you can keep the cadence confortable, and with any kind of real hill, I would be shocked if that was possible with a 42t as your smallest chainring.

Also, if you are putting a wrench on anything on a modern road bike, get a torque wrench or else expect to replace a lot of stuff... not that Gossamer parts are particularly highly thought of, but generally words like "heavy" and "overbuilt" would be used, not "fragile".

Homebrew01

"... Am I in trouble ?.."

As mentioned look on a chart. Find the lowest gear with your new crank and see what it equates to with your old crank. Only you know if it is low enoigh.

rpenmanparker 

OP, I don't understand why you went with a larger small ring when you appreciated the small ring you had for climbing and only needed a larger large ring. I would have tried the common 50-34 combination. Maybe 50 wasn't enough bigger than 48 in your estimation? You don't say anything about your cassette range, and I suspect this is what the whole problem is about. Does it go up from a high of 11 to a low of 27 or 28 teeth? The 11 tooth cog is the secret weapon for wide range from climbing gears to fast high gears using a compact crank. I think you attacked your problem at the wrong spot. I doubt you would spin out a 50/11 which is actually higher than a 53/12. Why does it matter? Because the 50 tooth front can be used with the 34 front while the 53 can't. So with the 50 you can have both higher and lower gears as you seem to desire. If you can cancel your order and rethink this whole thing, you may be more satisfied in the long run.

elcruxio

Price

I'm a poor student and just didn't have the 350€ to dish out on a new crankset. I got a deal on a FSA energy standard for 100€ and I jumped for it.

rpenmanparker 

I'm sorry. I do understand your situation, but wrong is wrong at any price. Based on your information, I don't see how you will satisfactorily ride the 42 tooth small ring. I believe you should have held out for a similar deal on a compact crank. Lower end FSA compact cranks can be had on ebay for less money than you paid, especially if you are willing to take a slightly used one or one taken off a new bike for replacement.

elcruxio

I hope it won't be that bad. It's not like I live in the mountains. Although in the north where I generally live I can get something like 500m of vertical climb in 50km.

And I'm young, adaptable and getting stronger every day. I calculated that since I have the 11-32 rear cassette and I have the 15 and 17 tooth cogs as primary cogs, I should get speeds from 21kmh to 35km/h with the four combinations of the two bigger rings. My atm sustainable endurance speed is 31/32kmh so it will take a bit of training yet to spin 90rpm with the 53 ring and 15 cog. I know it's doable in time and hopefully this will get me closer to my ultimate goal (40km in one hour time trial)

Rons

Back in the day we rode 52-42 all the time. Lots of guys rode that with a 12-21. I couldn't hack that and usually had a 24 in the back. Unless you are really heavy or climbing mts you should be okay.

topflightpro

Why not just buy a new bolt if that is all that is broken?

buffalowings

Well, if you haven't installed the crankset yet, you can still return it. Another possibility is a cassette in the rear with easier gears (12-28 or 30)

elcruxio

Apparently a new bolt costs as much as the offer I got on the fsa energy chainset. I moved fast since it's a limited time only offer and I didn't want have the bike on the docks for a month on the best road season.

The cassette is 11/32 ten speed apex so that eases it up quite a bit hopefully.
Today I checked that my commuter roadbike has a 52 as the big ring. I usually use the smaller ring with it at the moment, but that's because the saddlepost is too short and zero setback and the bike has no modern ergonomics. I can't put any power down with or if I try it feels like me knees will explode.
(Not to worry, modern stuff and a new seatpost are in the mail so comparisons can be made when the bike fits.)
It's a five speed, but I have no idea about the rear cogs or toothings.

elcruxio

And I of course mean that the non driveside crankarm is shot, not the bolt. The place where the crankarm broke is in such a place and made of so thin alloy that I lost all trust for fsa gossamer cranks.
I hope the energy set has a better design. If it's the same I just have to be super careful and go a bit below the torque recommendation

buffalowings

11-32 should be fine, I use a FSA energy 50-34 (bought for $100 shipped as well) with a 12-30 and the hills are killer where I live but I rarely used the lowest granny gear combo, with one particular hill, I had to get off halfway through the climb (it was really short but very steep).