thirdin77

I put a 46/34/24 crankset on my Tricross Sport because I wanted those ring sizes and they have worked out well.

At #185, though, and with a tendency to often get out of saddle to sprint, I've found that even after getting my chainline right and installing my Stronglight Impact crankset with a Shimano UN54 square taper bottom bracket per the instructions on bicycletutor.com, that it had developed a tendency to rub the chain on the front derailleur when I sprint out of saddle.

I actually have reinstalled the bottom bracket once and I've kept the crank bolts and chainring bolts tight.

As well, I had a Shimano Octalink triple which would would give me chain rub when I was out of saddle. Same thing, I removed/greased/reinstalled it and it was quiet for a few rides and then went back to chain rubbing.

Has any other 'heavy person' come to the conclusion that the old-style, cartridge bottom bracket-style crankset won't work for them?

Simply so as to get a stiffer crankset, e.g. an integrated spindle and outboard bb cups, I'm choosing between a Tiagra 50/39/30 or a Tiagra 50/34, with either a 12-26 or a 11-32 cassette. Yes, I've spent way too much time playing with Sheldon's gear calculator.

BTW, if anyone knows of a triple, 110 bcd cransket with an integrated spindle, outboard bb cups and will allow me to run a 45mm chainline, let me know. Or if there's a way to run one of the 50mm chainline MTB cranksets like the XT 48/36/26 crankset with my 130mm road hub, let me know.

JohnDThompson 

Why do you think the problem is the bottom bracket rather than the cranks?

tatfiend 

The problem could also be frame flex in the bottom bracket area. IMO this is most likely to be the culprit rather than the bottom bracket spindle flexing.

thirdin77

Never said it was the bottom bracket rather than the crankset.

I can't disprove this though my bike has a large, triangulated downtube and large-diameter chainstays so I doubt it's the bb area. I guess I could inspect for cracks.

I installed my JIS bb and crankset according to the instructions on bicycletutor.com and I used a torque wrench.

Should I have a bike shop reinstall them? Will the outcome be different?

Mondoman

It's usually tricky to figure out these things without being able to watch it happen and inspect the setup first-hand for stiffness, tightness, etc. I'd take the bike in to an LBS with a good rep and ask to talk directly with a mechanic -- that way they're focused on the actual issue rather than just reinstalling a component.

After a week of rain (and snow in the mountains!), I'm jealous of the fact that it's already been summer for a while on the Peninsula!

operator

How about telling us if the FD is adjusted properly to begin with...? Some combo's WILL rub, notably cross-chain combo's, and there's nothing you can do about it except stop riding a triple. WHICH front chainring/rear cog setup is causing rub when you sprint?

davidad

use the limit screws to allow the fr. der. to move slightly outboard. This may solve the problem. Not too far or it will overshift. You won't find much difference in the "stiffness" of the different cranks no matter what hype comes from the manufacturers.

Heckboy

I've got a tri-cross sport as well which I use for my 50 mile round trip commute. I'm a big guy with big legs and I often stand to run over little hills like freeway overpasses. I get some chain rubbing on the front derailleur when I'm doing this if I'm at or near the extreme positions on the cassette. It happened with the OEM FSA cranks and chain rings and it does it with the Sugino cranks and T.A. chainrings that I've put on the bike.

Frankly I'm not sure if it's the bottom bracket or the frame flexing and I don't care much. To me it's not a functional problem as I'm not getting any phantom shifts or other issues; just a little occasional rubbing. I've never owned or ridden a bike that didn't flex around the bottom bracket when hammering out of the saddle.

LAter,
HB

Road Fan

It sounds like a frame with a tendency to flex if two strong riders are finding this. But, Operator has a great point - you need to make sure the derailleur install is optimized. If it already is, fine. But if not, you might be alble to make it a liveable situation.

I also weigh around 185, but nowhere near racing strength. I have made my steel Masi and Trek flex noticeably in early season, when my pedal stroke is still a bit rough and I tend to mash. Later on I smooth out, and get no more derailleur rub on those bikes. Technique is another possibility. On the Masi I use the original vintage Campy NR crankset, and on the Trek I use a 1st generation Chorus. Both have Campy BBs. Problems like the OP speaks of do not show up when my pedal stroke smoothes out.

fuzz2050

It could also be chainring flex. smaller bolt circle diameters mean weaker chainrings (in equivalent sizes, of course). That's the main reason those fancy TA cranks never made it into wide circulation.

Wordbiker

If you want to check for lateral bottom bracket flex, stand beside the bike with one hand on the saddle and one on the bars. Backpedal the crank to 6:00, put your foot on it and push away from yourself. Just about any bike has some give in this direction, but as a big guy myself (230 lbs), I am particularly sensitive to excessive deflection, whether it causes derailleur rub or not.

Grand Bois

Which cranks are you referring to? The Pro 5 Vis?

thirdin77

I'm getting the chain rub at the front derailleur when I'm in my smallest or second to smallest cogs, the 12 and 13T cogs on my 12-26 cassette, while I'm in my middle ring which is a 34T.. which I've thought of changing to a 36T.

The chain rub is worst when I'm sprinting out of saddle though if I'm (not deliberately) mashing, I sometimes get that chain rub when I'm in saddle.

I could just shift into my 46T ring but I'm often either too forgetful or lazy to. That and because I'm used to sprinting out of saddle in my road bike's 39/12 and not getting any chain rub.

I believe the front derailleur is installed correctly in terms of height and its stops though I probably should recheck the rotation and I've been incrementally increasing the cable tension.

My experience is similar to that of Heckboy, I'm getting chain rub but not auto shifting or any functional problems.

I guess I could just live with it but I'd rather have a crankset that's as flex-prone or noise-prone in the first place.

That being, if anyone knows of a 110/73 or smaller bcd crankset with an integrated spindle, outboard bearing cup and a 45mm chainline, I want to know about it .

Garthr

What you may be experiencing is crank arm flex, not axle flex. You can see how much they flex just by standing next to your bike and applying pressure to one pedal. See how the ring moves with it? This isn't the axle, it's the arms. If tapered axles flexed so much, all bearing assemblies would wear out quickly from the intolerances. Outboard bearing assemblies are no better than traditional. The extra stiffness, if it can really be felt, would come from the larger axle and stiffer arms. That's the theory anyways.

Contributing to this....using you smallest cog with the 34 tooth small chainring. I'm surprised the chain doesn't rub on the 46t chainring. As operator stated, crossover triples don't have the clearance of a double FD. They always have a contoured cage that is supposed to help shifting, but it's really just a PITA. the very first triples in the early 80's were more or less a long cage double, with straight sides. They worked fine. I didn't invent the crossover triple.... so I'm just speculating here.... but when they were thought of, it was 5 and 6 speed freewheels. No problem to use the whole cluster. Now, with 8 and 9 speeds, you're asking for wider angles, and you cant' have it both ways. You can't have the "performance"(which is why they have the contoured cages), AND the wide cage needed to clear the angles.

One thing to try, is a double front D. If you don't have one laying around, they can be had used on eprey cheap. Yes, it's not supposed to work. So what..... I use a 105 double with 26/44/48 rings. the shift between the 26 and 44 is flawless. this will give your chain some extra clearance. If that doesn't work, look for an old school triple FD like a Shimano FD-MT60 that doesn't have all the contour of a modern one.



BTW, yes I do know of a 110 integrated triple crank you can run with a 45mm chainline. Surly Mr. Whirly. I've spoken to them about this. The short, 68mm spindle is designed for a 47.5 chainline. All you do is remove one of the driveside 2.5mm spacers, and you have the 45mm. Your crank will be offset by that 2.5mm to the left. If that bothers you, forget this idea. https://www.surlybikes.com/files/Surl...structions.pdf

Mr. Whirly's 100 triple is 58 BCD for the small rings. 20-24t.

I don't know if a new integrated crank will help you here. What you may get is nice new crank with the same FD rub. Try a different FD first.

BTW.... 185lbs isn't heavy.

Finally, is your frame Aluminum? Even it flexes. Combine all the attributes of the arm and frame flex, poor FD performance, and a strong rider riding a chain at severe angles ..... well..... how can that be a surprise it rubs?

Garthr

I'm sure those are the ones he's referring to. That's the only TA crank that flexes like a wet noodle, at least in the 185 arms I tried. The FD needed constant adjustment. They seem okay in the shorter lengths and small rings, but the rings really needed to be thickened with the small BCD. White Industries VBC cranks are an example of how to do it well.

The recent and new TA cranks are super. I use a Zephyr ,and am about to get a Carmina or possibly a Vortex(A 110 bcd compact), as they make the both in a 185mm size.... the only production cranks left for very short(155mm and long 185mm sizes). Otherwise it's custom.

professorbob

Frame flex.

illwafer

my vote is for frame flex. this happens on all my bikes (they are all steel), and i'm 180. you can either take it easy or adjust the FD so it gives you a little cushion.

Grand Bois

I'm questioning the statement that they never made it to wide circulation. They're probably the most popular touring cranks ever. You can still buy them new. Versions with the same BCD were made by Stronglight, Nervar, Sugino, Shimano and probably more.

https://www.velo-orange.com/pro5viscr.html

tatfiend 

Try riding with some of the old derailleurs such as the Super Record. Riders needed to trim the front derailleur after every 2 or 3 rear shifts due to the narrow rear of the FD cage. IMO FD shifters, including brifters, should have trim capability included in the design.

fuzz2050

ok, perhaps my statement is not as accurate as it could have been. TA cranks have long been sought after because the small bcd allows for very flexible gear ranges within a reasonable q-factor. Because of this, there are a few cyclists, evenly distributed around the world, who swear by the design. The design is indeed widespread.

However, the design posed problems, both from front derailer interference (Although sugino fixed that one), but primarily from the flexiness of the larger chainrings making shifting difficult. Those cranks are widespread, but uncommon.

And on a side note, I've never seen the Shimano version, care to post a link?

sunburst

According to the National Center for Health Statistics, the average weight for an adult male in the United States is: 189.8 pounds. Of course, in this world of cycling, where many of us look close to emaciated ...

bigbossman 

I weigh 230#, and have Campagnolo triple square taper cranks on all my bikes. I get up and mash on them every now and again, and do not have the issue you have.

I'm thinking frame flex, too.

DMF 

There's some frame and ring flex, but the issue is also (perhaps mostly) FD adjustment. Since you get it on the *middle* ring, the limit adjustments aren't relevant. Just trim the FD a little and it will stop rubbing.

In other words, **** happens. This is not a problem.

operator

190 pounds over what? The entire height spectrum? That statistic is as worthless as the quote without a context.

ScrubJ

This