Need to replace a Shimano crank set (no experience)

[Rekrul]

I just registered here to ask for help.

I have this bike;

https://www.bikepedia.com/QuickBike/BikeSpecs.aspx?item=91408

Which I rescued from the trash. I know how to do the basics, like changing a tube or tire, but I don't have a lot of experience replacing parts, or doing much bike maintenance in general. To be honest, I'm not a hardcore cyclist. To me, the bike is mostly just a way to get places when I can't get a ride. That said, I really miss not having it available when I want/need it.

Anyway...

The hole for the right side pedal is completely stripped. So far I haven't come up with any way to fix this, so I've come to the conclusion that it needs to be replaced. According to the above site, it's a Shimano Tourney FC-TY33, 28/38/48 teeth. Which seems to agree with what's stamped on the back of the left crank arm;



According to an old post here, you can replace this with a SHIMANO FC-M171 Altus Crankset (Black, 170-mm 48/38/28T 6/7/8 Speed) .

I see a few of those on eBay. What gives me pause is that they don't seem to fasten on like any of the tutorials I've watched. All of the videos show square/diamond shafts snugly fitting into a square hole, and then there's a hole in the end of the shaft that a bolt fits into. Mine has a threaded shaft sticking up through a square hole, secured with a nut, but it doesn't really look like the shaft itself is square. It looks more like there's a square hole that the threaded part sticks through, and that behind it, it might be more open/rounded.

I tried to get photos of it, but I'm not sure how helpful they are;



With the nut in place.



Nut removed.

You can see that the shaft doesn't seem to fit the hole.

Is this some weird setup? Will the Shimano FC-M171 work on this?

Note that I don't currently have a crank puller to take it off and look at the shaft behind it. I was planning to order one when I ordered the replacement cranks.

Any help is appreciated.

[Painkiller]

you merely have and old school nutted axle with cups and bearings. Today most BB are cartridge style. Once you get your crank arms off you need to measure the length of your spindle from the edge of the square part, Not the treads. The new crank if you go with the fc-171 requires a BB spindle length of 122.5 mm. That is the length i hope you already have or you should replace your Bottom bracket at this time. which would require more tools to remove the old and install the new. Bottom bracket spindle length is determined by the crank and size is determined by the shell of the frame..i.e. 122.5x68 or72

[Rekrul]

Thank you for the reply.

(10-19-2019, 08:49 AM)Painkiller Wrote:  you merely have and old school nutted axle with cups and bearings.

OK, but it still fits the same crank sets, correct?

(10-19-2019, 08:49 AM)Painkiller Wrote:  Today most BB are cartridge style. Once you get your crank arms off you need to measure the length of your spindle from the edge of the square part, Not the treads.

I don't currently have a crank puller. Locally they run about $20, but I can order one from eBay for under $10. Is there anything special I need to look for in a puller or are they all pretty much universal?

(10-19-2019, 08:49 AM)Painkiller Wrote:  The new crank if you go with the fc-171 requires a BB spindle length of 122.5 mm. That is the length i hope you already have or you should replace your Bottom bracket at this time. which would require more tools to remove the old and install the new. Bottom bracket spindle length is determined by the crank and size is determined by the shell of the frame..i.e. 122.5x68 or72

That's the length from one side to the other? I can't measure it accurately with the cranks on it, but for what it's worth, I stuck a tape measure on it and it's definitely longer than 72mm. Actually, it looked like it might even be longer than 122,5mm, but that may just be my inexperience and inaccurate measuring.

As for replacing the bottom bracket, I wouldn't even know where to begin. The more things I need to replace, the greater the chance that I'll screw something up. I'm leery of messing with things too much because if I make a mistake that's not immediately obvious, something could end up going wrong at the worse possible time.

Another question I had; Do I absolutely have to use a Shimano crank set, or will crank sets from other manufacturers work, as long as the measurements, mounting hole and number of teeth on the sprockets are the same? Is Shimano the best, or doesn't it make a huge difference to a casual rider?

[Painkiller]

yes your old style spindle will fit new square taper cranks. you measure the length of the spindle only, end to end . threads do not get measured, they only poke out to put a nut on to hold crank arms secure, they have nothing to do with the length of the actual spindle.
The best tool to get for removing cranks is the Park tool CWP-7 as it will be useful for removing other types of cranks you may encounter in your lifetime.
get the cranks off and get a proper measure of the spindle, if it is 122.5 you are good to go other than if you would like to service and re grease the bearings while it is apart. If it is not the proper length then get back and we can go from there.
You may buy other brands but the shimano are as good as any others and they plainly state the proper spindle use in Shimano Tech Docs. Other brands are vague in this info for their cranks.

[Rekrul]

I'm sorry, I didn't mean to ignore this thread. I never got an alert that you had replied again.

(10-19-2019, 05:16 PM)Painkiller Wrote:  yes your old style spindle will fit new square taper cranks.

Good to know.

(10-19-2019, 05:16 PM)Painkiller Wrote:  you measure the length of the spindle only, end to end . threads do not get measured, they only poke out to put a nut on to hold crank arms secure, they have nothing to do with the length of the actual spindle.

Understood.

(10-19-2019, 05:16 PM)Painkiller Wrote:  The best tool to get for removing cranks is the Park tool CWP-7 as it will be useful for removing other types of cranks you may encounter in your lifetime.

OK, I'll have to order one.

(10-19-2019, 05:16 PM)Painkiller Wrote:  get the cranks off and get a proper measure of the spindle, if it is 122.5 you are good to go other than if you would like to service and re grease the bearings while it is apart. If it is not the proper length then get back and we can go from there.

I'm a little confused about how the length of the spindle affects what cranks you can use. Could you explain in a little more detail why the length dictates what crank you can use?

(10-19-2019, 05:16 PM)Painkiller Wrote:  You may buy other brands but the shimano are as good as any others and they plainly state the proper spindle use in Shimano Tech Docs. Other brands are vague in this info for their cranks.

You mean as in what length spindle they work with?

[Painkiller]

The spindle length is determined by the crank set. The manufacturer of the crank, (i.e. Shimano) will tell you the length they recommend for a particular crank. It is all about proper chain line. If you end up with a new crank and do not know what size spindle they recommend, you can work around it by measuring from the edge of your down tube to the inside of your big ring of the crank you have on now. Then install your new one and measure it, compare what you have to your original. if it is + or- 1 or 2 mm you should be fine. if it is way long then you need a shorter spindle and if it to short you will need a longer spindle. 122.5 if yours is that is on the long side. get it apart, get proper measurements and go from there. But while your crank is still attached get the measurement from the tube to the teeth because it sounds like you going to go with another crank other than Shimano. So you can do the math when the time comes.

[Rekrul]

(10-21-2019, 09:52 PM)Painkiller Wrote:  The spindle length is determined by the crank set. The manufacturer of the crank, (i.e. Shimano) will tell you the length they recommend for a particular crank.

I just assumed that regardless of the spindle length, the square taper on each end would be the correct distance from the frame to hold the crank where it needed to be, so that you pick the right spindle hole, number of sprockets/teeth and you're good to go.

(10-21-2019, 09:52 PM)Painkiller Wrote:  It is all about proper chain line. If you end up with a new crank and do not know what size spindle they recommend, you can work around it by measuring from the edge of your down tube to the inside of your big ring of the crank you have on now. Then install your new one and measure it, compare what you have to your original. if it is + or- 1 or 2 mm you should be fine. if it is way long then you need a shorter spindle and if it to short you will need a longer spindle.

Hopefully it's the right size because I really don't want to start rebuilding the bike.

(10-21-2019, 09:52 PM)Painkiller Wrote:  122.5 if yours is that is on the long side. get it apart, get proper measurements and go from there. But while your crank is still attached get the measurement from the tube to the teeth because it sounds like you going to go with another crank other than Shimano. So you can do the math when the time comes.

At this point, I'm just collecting information and weighing my options.

I was in Savers the other day and they had an adult bike for $20. This holiday season I can probably find a new bike for Around $100 or so. On the one hand I like the idea of fixing this one, but on the other, if it's going to end up costing me $50+ I have to wonder about the wisdom of fixing it versus just buying a new one that will be in better shape.

I do like this bike, but to be honest, it's not in the greatest shape. I suppose someone who is well-versed in bike maintenance could take it apart, clean it up, make sure everything is working perfectly and make it like new. On the other hand, it takes me about an hour to put in a new tube. The handlebar assembly has four screws in it at the base and I only know what one of them loosens up. If the shifter cable ever snapped, I'd have no idea how to put a new one on and get it adjusted properly.

I have another bike that I rode before this one. Somehow I screwed up the derailleur on it. The hanger looks straight, the derailleur itself doesn't look damaged, but it's tilted away from the wheel both vertically and slightly horizontally as well and have no idea which part is bent. It happened when I was in a higher gear, I stopped got off the bike, got back on, shifted back to a lower gear (yes, I know, I probably shouldn't do that), and then ended up backing up the bike a little before the chain had switched sprockets. It came off the teeth and I figured it just needed to be put back on, but the derailleur was all out of whack and I don't have the first clue why.

I bought a cheap chain repair kit at Walmart just to get the tool, which was a piece of junk. I used it to break the chain thinking that I could just shorten, it bypass the derailleur and have it be a 1-speed bike. It took me about an hour to get the chain re-attached because the tool was seizing up and the pin was wobbling all over the place when I turned it. Of course I got done only to find that the chain was too loose to stay on the sprocket and at the moment I don't even have a working tool to return it to its original length.

Shows how much I know...

[Painkiller]

there is no problem being a total noobie, every one of us was one too at one time. This site has many videos in the repair guide section to cover what you are dealing with. Pick a bike of better quality and stick with it. A free bike can cost up keep money too, all bikes can. you save money in the long run becoming and learning to be your own wrench. Y our problem is not that bad, just normal happenings of bike ownership. A new improperly assembled $100 bicycle can be even more displeasing than what you already have, just prettier and that gets you no where.
you should try to look for a local bike co op or a repair class offered at a local bike shop can help a ton. If you are young and plan on bicycling for many years, get the tools you need along the way. Many of the smaller tools can be purchased cheaper than the local bike shop labor for the said job. Start by believing in your self with an I can do it attitude, relax and think things thru and go from there. I know you can do it!

[Rekrul]

(10-22-2019, 07:12 AM)Painkiller Wrote:  there is no problem being a total noobie, every one of us was one too at one time. This site has many videos in the repair guide section to cover what you are dealing with. Pick a bike of better quality and stick with it. A free bike can cost up keep money too, all bikes can.

I've been fairly lucky in that I've found bikes that haven't been in too bad condition. I don't know how many other area have this, but twice a year we have Bulk Trash Pickup where the city will haul away almost anything you put on the curb for free. People use this opportunity to clean out closet, attics, basements, garages, etc. This last BTP my friend brought home three lawn mowers. My own came from BTP. Of course you have to get to the stuff quickly because the scrap dealers grab anything made out of metal.

I have some other bikes, but they're all in a state of disrepair. Another mountain bike has a front wheel that's not round and loose spokes. A road bike (skinny tires, curled under handlebars) has really tight steering, so much so that even someone used to that type couldn't ride it. Another, almost identical road bike had the rear wheel fall off in the shed and the derailleur is off. To be honest, I could never ride those type bikes. I brought them home because I thought I could get used to them, but that never happened.

I actually passed up a couple bikes that didn't look too bad this last BTP because I also have a hoarding problem and with all the ones I already have, I was trying to resist the urge to add even more. Now I'm thinking I should have grabbed them.

I've only been riding casually for the last 10-15 years or so. And by casually, I mean maybe a few times a month to get to the store or the doctor. I sometimes go out on the bike during BTP, which is probably when I spend the most time on it. I have a luggage rack on the back with a plastic milk crate bolted to it for cargo because I'd kill myself if I ever tried to ride home carrying a gallon of milk.

(10-22-2019, 07:12 AM)Painkiller Wrote:  you save money in the long run becoming and learning to be your own wrench. Y our problem is not that bad, just normal happenings of bike ownership.

I talked to the bike shop again today and they had the puller you recommended for the same price as online. Previously they only quoted me the price for the larger tools with a handle. I stopped in and bought it.

I got both cranks off (I forgot to measure between the frame and the sprockets first though). The drive side was a pain. The pulled didn't want to thread in at first and it took me a while to get it caught. Once they were off, I measured the spindle and it's 122.5mm.

(10-22-2019, 07:12 AM)Painkiller Wrote:  you should try to look for a local bike co op or a repair class offered at a local bike shop can help a ton. If you are young and plan on bicycling for many years

I'm 52 and not in the best shape.

(10-22-2019, 07:12 AM)Painkiller Wrote:  get the tools you need along the way. Many of the smaller tools can be purchased cheaper than the local bike shop labor for the said job. Start by believing in your self with an I can do it attitude, relax and think things thru and go from there. I know you can do it!

Is there a reference online somewhere for which Shimano cranks fit which size spindle? I looked on the Shimano site, which is confuing, and all I found were PDF files listing the various components.

Since the Shimano FC-M171 28/38/48 seems to be in short supply and/or more expensive, I was wondering if one of these would work;

https://www.amazon.com/Altus-28x38x48t-170mm-Square-Guard/dp/B005531XR6/
https://www.amazon.com/SHIM-CKST-TOURNEY-TY501-GUARD/dp/B01M63HV33/

Or are they cheaper because they're lower quality? BTW, my rear shifter is 7-speed.

Also, one last question;

Does the crank length make a huge difference as far as how much resistance you feel while pedaling? In particular, I'm wondering if a 175mm crank would feel significantly harder to pedal when going up hills than a 170mm.

With my old bike, I struggled to get up some hills in 1st gear and often had to walk it up because I was too out of breath to continue. This bike (with 170mm cranks) I could pedal up the same hills in 3rd gear most of the time although I occasionally switched to 2nd. I wasn't specifically looking to increase the size (although I am 6' tall), but while looking, I see some that match the other specs, but are 175mm instead of 170mm. If the extra 5mm wouldn't make a lot of difference, I can go with either, but if it would make it harder to pedal, I'll be sure to get 170mm, like I'm used to.

[Painkiller]

Glad you got it off and measured, 122.5mm is sweet. Do not know what puller you bought but the one with the handle offers no leverage, is tough on the hands with stubborn cranks. the one I said to get can be used with a wrench and just works better down the line.
170mm vs 175mm is longer is more leverage so should be easier to peddle slightly. assuming the gearing is the same. no biggie either way.
If you can, go for the FC-m311 and it will be an upgrade and also it will use the 122.5mm spindle. you are good to go!

[Rekrul]

(10-24-2019, 05:27 PM)Painkiller Wrote:  Glad you got it off and measured, 122.5mm is sweet. Do not know what puller you bought but the one with the handle offers no leverage, is tough on the hands with stubborn cranks. the one I said to get can be used with a wrench and just works better down the line.

I got the Park Tool CWP-7. Luckily I had an old adjustable wrench to put on it, since most all the wrenches and sockets I have are imperial, not metric. I have a few smaller assorted metric sockets among the few tools of my grandfather's that weren't tossed/sold/given away, but usually every size except what I need.

The majority of my tools were inherited from family members and with a few exceptions are the usual hodge-podge of mis-matched and incomplete sets that families often end up with. Need a certain size screwdriver? Let's dig through the junk drawer to see what we can find!

(10-24-2019, 05:27 PM)Painkiller Wrote:  170mm vs 175mm is longer is more leverage so should be easier to peddle slightly. assuming the gearing is the same. no biggie either way.

I went with 170mm just because it was easiest.

(10-24-2019, 05:27 PM)Painkiller Wrote:  If you can, go for the FC-m311 and it will be an upgrade and also it will use the 122.5mm spindle. you are good to go!

I just placed an order for the FC-M311 from Amazon. Estimated delivery Oct. 28-30. So hopefully I'll have a working bike by Halloween.

What I hope to do is to get this bike working again, then get my old bike (the one with the messed up derailleur) fixed and once I have a spare, maybe I'll try doing a little more maintenance on this one. Cleaning off the caked-on grease would probably be a good start. It didn't have a kickstand when I found it and the black one I put on from K-Mat is now all rusty. It still works fine, but looks like crap. Plus the BB could probably use fresh grease, although at the moment the only thing I know about that is that it can be cleaned and re-greased. I have no idea what's involved in doing that yet.

Hopefully, I can also restore the other bikes I have to working order. I'm one of those people who hates to see something go to waste if it can be fixed up and used by someone.

BTW, this is my old bike, no idea of the year;



I put a different, wider seat on it some time after this photo was taken because sitting too long on that one started feeling like I'd been straddling a 2x4. I'm not crazy about the shifters on it. They're not "indexed"(?), so you just kind of move the lever until you feel the chain switch sprockets. Occasionally the screw holding the shifter together loosens up and it starts changing gears on its own until you tighten the screw.

[Rekrul]

I just realized that I never posted a conclusion to this thread.

The crankset came back in the end of October, around Halloween, I put them on, screwed in the original pedals and all seems good. I've ridden it a few times since then, although I'm not sure how much I'll be using it now that the weather has turned cold.

I did notice that when it's in 7th gear and the chain is on the smallest rear sprocket, the chain rubs on the front derailleur cage. I rarely go to even 5th or 6th gear, so I'm not sure if it did that with the old cranks or not. I imagine that I can adjust it as it's only rubbing very slightly, but I haven't even thought about it since I never even use 7th gear. Pedaling in the higher gears can take a lot out of me, especially if it's on even a slight incline.

Anyway, success! Thanks for all your help!

[Rekrul]

I could use a little more advice...

I installed the new crank set months ago and have been riding the bike occasionally since then, although not as much since the weather turned cold and rainy.

The other day it was nice out and I rode my bike to the store. I didn't notice anything out of the ordinary, but on the return trip, the left (non-drive) pedal didn't feel right. When I stopped to check it, I saw that the entire crank arm was loose. In fact, it fell off in my hand. Somehow the nut had worked loose. If I hadn't put the plastic dust cap on when I changed them, I would have lost the nut somewhere. I didn't have any tools with me, but I managed to screw the nut on a tiny bit, made it halfway home and walked the rest.

When I put the crank back on, it would only go on a tiny amount and the threaded shaft only stuck up into the hole a tiny bit, just barely enough to catch the nut on. It was this way when I first installed it as well, although I don't remember if the original was like that. I used a rubber mallet to gently but firmly tap it down a little more and managed to get about half the threaded shaft to protrude into the crank. I put the nut on and tightened it literally as tight as I could get it using a large (like 1') socket wrench, but the crank didn't go on any further. The end of the threaded shaft isn't even flush with the surface of the nut. In other words, the nut is only screwed on about halfway.

It's tight at the moment, but I imagine it will eventually loosen up again.

Is this a known problem that has a definite fix? Should I just put thread locked on the threads before screwing on the nut? I'm reluctant to take the crank off and file the hole to make it fit down more because I don't want to do it unevenly and cause the crank to have a sloppy fit on the shaft.