I don't think so, because all the hollowtech cranks I see are ugly. I'd just get a sealed bb. All that flex could be your frame, you never said what it was, or how big it was. My Schwinn Probe would flex when I washes on it, it's the biggest size they came in.

I had the same experience upgrading a '97 Colnago steel frame from square taper to Campy Ultra Torque. It changed the chainline to improve the shifting esp on the front. Plus it looks cool :)

Absolutely just going from square to outboard bearings is huge! Do it!

Everything depends on where this bike fits into the scheme of things going forward. As an entry level bike, it may not be worth it. Especially when better pandemic bikes start hitting the used market at reduced prices.

I ride 8 speed, but my stuff is old, however the vast majority of people would not waste money on that level. If you see yourself moving on in a couple of years it might not make sense to “change” cranks.

As far as chain rub on a derailleur cage “only” when sprinting, I’d probably live with it. There is no guarantee that the new crank won’t do the same.

John

I wouldn't put much money into a bike equipped with Claris or similar. Small things like consumables are fine, brake pads, cables and housing make sense but cranks not so much. I might buy pedals and saddles but those I can transfer to a better bike down the road but beyond that I would save the money.

As others have said a nicer crank won't stop frame flex.

I have square taper on two road bikes (old Suntour on one, White Industries titanium BB with old school Dura Ace crankset on another), and BB30 with Ultegra Hollowtech on a third. Any difference I think I feel is due to the frame, not the bottom bracket. It doesn't translate to better performance for me. I'm not strong enough or fast enough, and we don't have any real mountains where some slight differences might matter.

Strong, heavy sprinters might notice some difference in stiffness of the BB and stiffer cranksets. I can't. My "sprints" are a pro's "loafing along in the grupetto" power.

But the swap is pretty easy. RJ the Bike Guy has an excellent video tutorial on YouTube.

^ this has been my experience also. 100%

Until recently I loved all the newer crank systems coming out because it orphaned so many square taper cranks. I'm 6'5" and I ride 180mm cranks. I have been able to stock up on older, good condition, high quality used square taper cranks. All my bikes now have these longer cranks thanks to the I gotta haves. I own one bike with an early ISIS crankset and I can't tell the difference between square taper cranks, ISIS, or even a Profile 180mm BMX crank I have on one bike. I started out on a one piece crank on a Columbia when I was a kid and all I remember about it was how durable and reliable it was. I'm in the wear it out camp. Frame flex is most likely your culprit but I have been wrong once or twice before.

A stiffer crank arm or crank axle should transfer more force to the frame, making the frame flex more while pedaling.

Thanks for all your insights, everyone :) I decided I won't be upgrading... until the chainring gets worn and needs replacing. In that case, I'd just replace the whole crankset with the Claris one.

Would an upgrade to compressionless brake housings make sense? I feel a bit of friction when using the rear brake lever; it's not as smooth as the front one.

I switched from a square taper bottom bracket to a Hollowtech on my Birdy. It and the new crankset are significantly lighter than the original parts. The installation is easy so long as you get the proper parts with the correct threads and width. You can get the tools on Amazon for less than what a bike shop will charge you to make the conversion.

Compressionless housing is not really primarily meant to reduce friction, but to act as less of a 'spring' along its length so brakes have a more rigid connection to the lever. If you feel roughness or friction, those are usually caused by housing that is dirty, kinked, or has a mangled coil at one end interfering with the inner cable, or a kinked or frayed wire in the inner cable. It is likely replacing the inner cable and cable housing with any lined housing will improve brake feel as long as it is properly cut and the ends finished correctly. Compressionless housing will give a bit crisper brake feel but I believe is of limited benefit to actual braking. Others may have a different perspective.

Tried Claris front derailleur and not impressed. Have FSA rings on one bike, and I am reasonably impressed--pretty much equivalent to Shimano 105 rings. I (as we all did) used square-taper for years and years and were much impressed with them compared to the old cotter-pin cranks.

Hollowtech is my absolute favorite non-pressfit BB system and according to engineers, is stiffer because the bearings are wider, closer to the load (crank/spindle attachment.) Can't say as I ever noticed a difference--except Hollowtech is a lot lighter .... but I am not, so spending money to save grams is silly, for me. Your mileage will vary.

Frame flex .... only one thing to change there, and that's the frame. But if all that is rubbing is the chain, and only on sprints .... not Too bad for a cheap-ish bike. Maybe ride less and lose fitness? ;)

As for upgrades ... Definitely. Save up for a better bike.

The thing is...

Even on entry level bikes, the frame is the same from Claris to 105. Unless different forks.
The cost difference being components.

I bought a sora bike over 105 for the color. Sora came with qt.
I threw on Ultega Outboard. Bought a praxis crank.
So I stiffened it 2 ways , 1 being the bb and 1 being crank/chainrings.
And I also regeared at same time. Win, win win.

My loss being it was a 1100 bike. Then I sold it for $700.

So while I do argue for changing the bb / crankset. $25 bb , and $50-100 for used crank.

A decent used bike with 105 could be had for 600-800

While you might get 300-400 out of yours.

I tinker all my bicycles though. It is the hobby I spend money on. It is just part of life.


If you can afford it... do the upgrade.

Some of us will buy 3 chains per cassette.

While others won't buy a chain until they need a new cassette, new rings and a chain.

Some won't buy tires until they see cords.

Some people ridecrubber garden hoses. I'll take brand new garden hose tires off, and buy gp5000 tires.

It is your ride, make it into what you want to ride!

The alternative being ... Smart Shopping.

Anyone who cares .... will look at the frame .... Particularly if the frame was the whole issue.

Why would anyone who bought an entry-level bike and was unsatisfied with the frame buy The Same Model, just with better components?

The whole point about buying a better bike is ... Buying a Better Bike.

A lot of manufacturers used to (I haven't bike-shopped in a few years) sell a couple entry-level models, then a better model, then a CF model. Giant's Contend comes to mind. The first model (or maybe the first couple models) had a basic Al frame, then the next model had an upgraded Al frame, then there was a couple CF models.

If the guy bought a bike with a weak frame, why sink money into the components? Sure, it's only $25 for the BB, but them also the cranks, and the cheapest I can find (Claris, pre-tax and shipping) is $105? Now he is $130 into the bike and guess what, the only issue, which was the rubbing chain, is Still There. Changing the BB and cranks won't In Any Way stiffen the frame. Nothing will.

So yeah .... tolerate a little rub while sprinting, and save up for a better bike with better everything. Not the same model with better components. Only an unsmart shopper would do that.

Funniest part is where you say ..... So … he could Not blow $130-$150 (tax and shipping) on parts which In No Way address his problem ….. sell his old bike for $400, save for a month, and shop around for a quality used bike with a better frame and better components …….

But some people suggest he sink $150 into a bike which he already knows doesn’t work for him and never will ……

I tinker with my bikes too … but if I have a problem I need to fix, I fix it. I don’t replace non-involved parts with more expensive parts and let the problem remain.

But that’s just me. When I fix things, I like to start with the things that Need fixing.

We what frame does he have?

I speak facts and real experience, when I say yes will fix his chain rub. Will it magically turn it into mi himod with hollowgrans spiderweb stiffness. No!

When I ditched my QT and fsa for a praxis plus ultegra outboard it totally fixed chain rub,

So in my experience it was worth fixing it via fixing bb and cranckset/chainring.

I was wondering. When changing bottom brackets, would facing be necessary?

Very few bikes get hammered in the same way a track bike does. Small tracks have high g forces , standing start events put a lot of power through the crank, and short, fast sprint events put a strain on drivetrain parts. Plus, some of the sprint specific track guys are 200 lb guys who squat 400 lbs (or more) and put from 17 or 1800 watts (local fast guys) to 2500 watts (pros) through the cranks

Lots of square taper bottom brackets still being used. For high level usage, the Dura Ace track crank is probably the most popular, but the Sugino 75 and Campagnolo Pista are not far behind, -- The Campy and Sugino products are still square taper


Point being : Upgrade to your hearts desire - we all do it, but just dont kid yourself into thinking any performance gains will be had outside of possible weight reduction

I didn't care about flex on my capo knock off Kinese made aluminum frame. Because for 1 it never interfered with shifting...
For other people there really isn't a good option other than QT for getting the correct chain line on a track bike. See photo.

On my Dawes sst kinese made with canndale capo chain stay knockoffs. I ran it free wheel. I had a cx50 crank sitting around an older still good ultegra bb.

For giggles I put it all on and with the absolute back 52 oval chainring my chain line while not perfect was close enough. Close enough that the oval never pulled chain off, even on the bumpier of roads.

So basically I am 2 : zero on hollowtech being better and improving efficiency.
Funny thing is I was too lazy to just buy a new st bb. And the life expectancy of a bikes bb being ridden in all weather, humid weather, with a square taper, will be less than that of an outboard bearing bb. start sawing on them, and that life drains fast!
https://cimg8.ibsrv.net/gimg/bikefor...756582d8d1.jpg

Edit: the downfall of an oval on a singlespeed, is anything north of 120 rpm gets difficult to spin.

Btw, what is your bike? Year brand