PatrickGSR94

I got my wife's bike from BD a few months back, and recently noticed the pedals wobbling while riding and turning the cranks. I thought maybe it was the cheap POS plastic pedals it came with. So I picked up some alloy Wellgo bear traps the other day, and wow the bearings are like night and day difference, and surprisingly about 100g lighter for the set than the plastic pedals.

Well I noticed as I was threading the new pedals in that the pedal again wobbled as I turned the threaded spindle into the cranks. I'm thinking the crank holes are drilled out of square or something?

So anyway now I'm looking for a replacement triple crankset, preferably 48-38-28 to match what's on there. What would be a decent quality one to look at? The bike has Tourney parts on it, but the steel crank arms look even worse than the Shimano Tourney triple cranksets. Any other ones I might consider other than Tourney, that won't break the bank? Probably don't want to spend more than about $40-$50 for the crankset.

PatrickGSR94

Also when the cranks turn, it looks like the chain rings are slightly off-center, so the rings move eccentrically around the BB spindle, which causes constant fore-aft movement of the RD jockey wheel arms. Basically the whole crank setup on the bike is a total POS.

How can I tell what BB the bike has? All I know is it's a square tapered spindle.

FBinNY 

As long as you have a sq. taper spindle, just about any crank you're likely to find will fit.

The key is spindle length, and you can measure that once the cranks are off.

Greyryder

If it's wobbling as it's being threaded in, I have to think it's the pedal, not the crank arm. Doesn't matter what angle the hole is drilled at, it wouldn't cause the pedal to move back and forth as it's threaded in. I think all pedals that don't use cartridge bearings have some innate wobble. Or at least, the cheap ones do.

Asi

Simple explanation: the crank is bent (most likely inwards from a fall)

Or the pedal axle is bent (but for 2 different pedals? I doubt)

Homebrew01

I was thinking the exact same thing.

If the hole is drilled at an angle, or the crank arm is bent, you will notice while riding. Your foot will tilt inwards and outwards as it goes arond.

Retro Grouch 

Try threading in your new pedals from the wrong side of the crank. If they look OK and start easily with just your fingers, run them all the way into the crank arm. That will repair any minor thread damage in your crankarm.

PatrickGSR94

Doubt it's the pedals, because as was mentioned both sets of pedals do the same thing.

Bike has never taken a fall as long as we've had it. Crank arm bent out of the box? I wouldn't even doubt that for a second. I really hate the look and feel of the steel crank arms on this bike. When turning the pedals, the chain rings and everything seem to wobble both laterally and radially. The RD jockey wheel arms move fore-aft constantly due to the radial wobble of the chain rings, and the chain seems to always touch one or the other FD plate at some point in the rotation because of the lateral wobble.

Could any of that wobbling be coming from the BB itself? Just wondering if I would need to replace that in addition to the crankset.

Homebrew01

The BB bearings could be loose. The cranks could be loose. Can you post a picture of the crankset ? Sounds like some odd problems there.

HillRider

My first thought is to contact Bikes Direct with your problem.

PatrickGSR94

I can get a picture later. Here's a link to the bike on BD, but even this one has better-looking crank arms than on my wife's bike: https://www.bikesdirect.com/products/...white_2100.jpg

Here's my wife's bike, I'll have to get a closer pic of the crankset later. The crank arms just have a really rough texture on part of it, with black paint on it, almost like it wasn't machined very well, and then just spray painted.

PatrickGSR94

BD website pretty much says after 30 days it's not their problem, and to contact the manufacturer instead. We bought it in February of this year.

achoo

Well, that's the bad thing about Bikes Direct. They're inexpensive because they don't have any real customer service.

Were it my bike, I'd just get another crankset and if necessary a bottom bracket and replace it myself. That's not a high-end crankset on that bike. You should be able to get a much better one for not too much. Maybe like this:

https://www.amazon.com/Shimano-FC-M17...d_sim_sbs_sg_1

PatrickGSR94

Yeah I didn't plan on going through anyone about this, but instead just getting the required parts which will be an upgrade anyway to what's on there now.

I think I looked at that one last night. Some of them say "requires 123mm BB" which I assume is the length of the spindle. What's the best way to check that? If I remove the crank arms I'm not sure my digital calipers are deep enough to measure the spindle length of the installed BB. They might, though.

PatrickGSR94

Dang I would probably order that Altus crank today if I thought I could get it here before we leave on our trip Friday. Probably not possible, not without a ton of shipping costs anyway.

FBinNY 

You don't need calipers. You make one from a sheet of cardboard with a cutout to clear the BB. Extend the cutout until it matches the spindel, then measure with ruler.

SkyDog75

You could sign up for a free 30-day trial of Amazon.com's Prime membership and get no-cost two-day shipping. The following items are available via Amazon Prime and you could have them by Thursday:

Shimano M131 Crankset (170mm, 48/38/28) - $24.20
Shimano UN55 Square Taper Bottom Bracket (68x122.5mm) - $19.27
XLC Crank Arm Extractor - $7.99
Park Tool BBT-22 Shimano Sealed Cartridge Bottom Bracket Tool - $16.95

You'd need a Crank arm Extractor to remove your current crankset and a bottom bracket tool to install the bottom bracket, so I listed Prime eligible options you could include in the same order if necessary.

You might not need a bottom bracket if your current one is the right length, but you may not know its length until you remove your cranks and measure. If you can reuse your existing bottom bracket, great! Just return the bottom bracket and tool at your convenience.

fietsbob

Bikes Direct seems to buy use of old familiar names , then gets Asian Factories to use them, on bikes .

had you not skipped the dealer , in quest of a bargain , they would be there to help you..


though for a fee they can get the crank that was a defective 2nd, replaced , without buying all your own tools..

PatrickGSR94

Crank extractor? Couldn't I just knock the old crank arms with a good 'ol hammer?

What's better, the M131 Tourney crank or the M171 Altus? Reason I ask is that I can't seem to find the M171 sold/shipped directly by Amazon.

I'm not going to worry about it right now, I'll wait until after our trip. I don't want to have my wife's bike all in pieces on Thursday afternoon when we're leaving at around 6 AM Friday morning.

SkyDog75

I tried that once on a frame I was going to toss anyway, just for kicks. While it was fun trying, I couldn't get the crank arms off with a four-pound hammer or a pickle fork.

The only substantial difference I can seem to find between the M131 and M171 cranksets is that the M131 is only available in a 170 mm length while the M171 is made in 170 and 175 mm versions. And the plastic chain guard is cosmetically a little bit different. Otherwise, they mate to the same bottom brackets, require the same spindle length, come in the same chainring configurations, and even share the same PDF documentation on Shimano's web site.

PatrickGSR94

hmmm wonder which one is lightest

PatrickGSR94

Went ahead with the M131 crank with the silver arms. I put all that stuff, plus the FR-1 freewheel removal tool, on a Save For Later list. Will probably order when we get back in town next week.

onespeedbiker

Do you just assume the pedal has been wobbly from the beginning and your wife has never ridden the bike without you being present? As mentioned, the usual suspect of a wobbly pedal is a bent crank and a steel crank arm bends easier than aluminum. I know you already bought a new crank, but you may want to try to bend the steel crank arm out as if is was bent in. I have done this with steel crank arms before and it doesn't take that much effort; just get a piece of pipe that is big enough to slip over the the end of the crank arm.

SkyDog75

OK, now I'm curious, too... According to one retailer's web site:

M131 = 955g
M171 = 1063g

PatrickGSR94

I can tell you for a fact that she has never ridden it by herself, because she's not really prone to riding unless it's with me and I suggest we go ride. Plus there are no blemishes whatsoever on the crank arms, pedals, or anywhere on the bike for that matter.