Advice Needed - Pedel Sheared Off Crank Arm - Images Included

[Cycling_Man]

EDIT - UPDATE ON CURRENT SITUATION BELLOW ORIGINAL POST- EDIT

ORIGINAL POST
Hi Guys. Thanks for taking the time to read this I just need some help. The bike I got has encountered an issue where the threads in the crank arm where the pedel screws into have completely shearn off. I camr to use the bike today and when I was putting presser on the pedel I could notice movement in the pedel. I looked down to see that the pedel was able to move. I thought this might off just been an issue where the pedel had come lose so tightened the pedel and it seemed to be fine. However stright away again the pedel came lose and when removing the pedel I could see the the threads inside had been shearn completely off due to the metal flakes inside and the the fact that threads were bascially smoth. I have no idea how this had happened. The other pedel seems complete fine. When removing the pedel there were no washers or anything I believe but not sure if that would be the problem. When I was doing a quick ride yesterday (just like 5k) I noticed the pedel has a little bump to it. I didn't stop to look which now I know is pretty dumb but I thought that I would just get home then have a look since I had no equipment with me because I was literally just going round the block. I got in and it was late so went to bed to look at it the next day and noticed what I described above.

I am not a "bike savy" person so am unsure of what to do. I know the best thing to do is to take it to a bike shop to get it looked at but I wanted to ask you guys first incase I get ripped off for parts that I don't need if there is another way to fix this or if they are just stright up overcharging me. From the research I have done it looks like I will need a new crankset. Like I said above I am not "bike savy" but they look to be fairly expensive and I will most likelyl have to pay for the cost of labour too unless I could figure out how to do it myself which I don't mind but I don't want to make things worse. I do not know what crankset the bike has at the moment, maybe you guys could help with that too.

Have any of you guys expericed this issue? If so do you know why it occured, what you did to fix it, and how much it roughtly cost you. I have linked a few images bellow so you can see what I am describing.Thanks in advance, Cycling_Man.

Bellow Are Some Images Of The Issue

EDIT - STORY UPDATE

I have taken the bike to a few places (3 in total) and here is the update.

The first shop I went to was good. They told me that they would need to replace the whole chainset and if they did that they would have to replace the chain too. They also told me that if they might have to change the rear cogs/gears too. All in all they said for parts I would mmost likely be looking at around £100. I suggest to a part that another user on this post said would work, a new chainset without the chains, just the cranks and through axel (https://spacycles.co.uk/m8b0s109p4710/S ... ple-Cranks) and he said that would work if the measurements matched. He was helpful in giving me the information I need, not giving me so much and explaining it, saying that this part would work if it meausred up right and also told me the bike has a square bottom bracket. When I said what they would do with the bike if I was to go with them they said that they would replace the crankset, so I believe they wouldn't order the part and change it.

The second guy was okay but I found it hard to get a word in. He seemed to talk a lot, kind of overloading me with information and as a person who doesn't know much about bikes it was kind of a lot to take in and when I tried to suggest something he would start talking again. Anyway, he told me that I would have to replace the whole chainset, get a new chain, new rear gears and maybe even a new bearing. He gave me a rough estimate that it would probably cost upwards of £200 and I don't even know if that included labour. I suggested the part that I suggested to the shop above and he didn't seem to convinced. He didn't seem to be as helpful as the other guy and just felt hard trying to communicate with him.

The third guy I went to was super friendly and helpful. I brought the bike down and he told me that the teeth on the chainset looked good so I woudn't need a new chain most likely if I bought a new one and also told me that I could put the old teeth on the new chainset, meaning that I wouldn't for sure need a new chain and rear gears. He was also very helpful and seemed like he wanted to work with me. He told me the bike had a 110 BCP (from his rought measurements) and told me information to try to find parts myself which he could fit. I didn't even ask him to do this. He just told me what I needed to know if I was going to look for a new crankset which made me like this guy even more. He also tells me that it is possible to change just the crankarms and use the old crank rings. He took my number and literally a few hours later he had sent me a part which was a crankshaft that contained no rings, just the arms and the through axel which he said would work and would be the only part I needed to change if the measurements were right which was great because the part was around £25. The only incrimental thing is the colour. It is silver and I would prefer it be to black to match my black bike but if I can't find any then I guess I will just go with this solution for now because it is only around £25 +labour to get the bike back up and running and I guess I could upgrade the crankarms or the whole crankset when I need to replace it.

I think I am definitely going to go with the third guy since he was so helpful and went out of his way to try to help me come to a solution that wouldn't require me changing a load of parts and costing me lots.

[rjb]

That chainset is toast. You could have it repaired but it will cost as much as a cheap replacement chainset. Check the pedal you have is marked with an R to indicate its a right hand pedal. If it has an L on it its a left side pedal and would explain how the threads are stripped.
Sometimes the pedal installer can cross thread the pedal when screwing it in because its not been inserted square but at a slight angle which could be another reason for the failure.

[Cycling_Man]

That chainset is toast. You could have it repaired but it will cost as much as a cheap replacement chainset. Check the pedal you have is marked with an R to indicate its a right hand pedal. If it has an L on it its a left side pedal and would explain how the threads are stripped.
Sometimes the pedal installer can cross thread the pedal when screwing it in because its not been inserted square but at a slight angle which could be another reason for the failure.

Hi, thanks for getting back to me. The pedel is the right pedel and so was the right pedel from that arm. Do you happen to know how much this could cost me and where I could potentially get some decent parts. What would you suggest for me? Like I said I am not a bike savy person but I do know that this part is pretty vital (obviously haha) so think it is going to cost a bit. I know you can't say for sure but if you were to give me a rough quote on the price something like this would cost what would you say and would you suggest I try to fix it myself or pay for someone to?

Thanks.

EDIT

Just to throw it out there I know there is a £50 voucher you can claim for the government to help get your bike back on the road if you are using it for work which I will be so this would help reduce the cost if I pay for someone to fix it instead of trying to fix it myself and buy the part out of my own pocket if I am reading correctly so might actually be cheaper to get someone to fix it.

[jimlews]

Time for a new right hand crank, I'm afraid.

The good news is:

https://spacycles.co.uk/m8b0s109p4710/S ... ple-Cranks

As long as your existing crank set is either 165 or 170mm crank arm length ( it will be marked on the inner face of your crank arm) and square taper bottom bracket axle, these should be more than good enough. Buy a pair of pedal washers while you're at it. When you refit the pedals, DON'T torque them up too tight. Or get a competent bike shop to fit the whole thing for you.

Make sure there is no alloy from the old crank in the pedal threads when you come to refit. Pick it out with the point of a bradawl or something. A smear of grease on the thread after you've cleaned it is a good idea.

[Cycling_Man]

Time for a new right hand crank, I'm afraid.

The good news is:

https://spacycles.co.uk/m8b0s109p4710/S ... ple-Cranks

As long as your existing crank set is either 165 or 170mm crank arm length ( it will be marked on the inner face of your crank arm) and square taper bottom bracket axle, these should be more than good enough. Buy a pair of pedal washers while you're at it. When you refit the pedals, DON'T torque them up too tight. Or get a competent bike shop to fit the whole thing for you.

Thanks for getting back to me.

Are you saying that I do not need to purchause a whole new crankset as if so that would be good.

As someone who doesn't know much about bikes I am not sure what you mean when you are talking about the bottom bracket axle but I looked at the inner face of the crank arm and it has written (stamped) 170UA01. Would these be compatitble? I don't know much about bikes and at the moment there is a government sceme where you can get a £50 voucher to get your bike back on the road if you use it work work so that would help reduce the price and would mean I won't be able to break anything haha.

Thanks for your help and look forward to hearing back from you again, Cycling_Man.

[jimlews]

If you check the link, you will see that that crank set is only available as a set. So if you decide to buy that, you might as well replace both arms. If you are unsure of your mechanical abilities, take it to a competent bike mechanic.

I think that the 170 bit means that your crank arm is 170 mm long (Centre of the bottom bracket axle to centre of the pedal axle)

[rjb]

The fix your bike voucher would give you £50 towards a repair. i think this is the best way forward in your circumstance.

[Cycling_Man]

If you check the link, you will see that that crank set is only available as a set. So if you decide to buy that, you might as well replace both arms. If you are unsure of your mechanical abilities, take it to a competent bike mechanic.

I wouldn't mind buying both and having to replace then but I wouldn't know if they would be compatable since I don't know much about bikes.

I would just like to ask you if you think that I can fix this issue with just purchasing new crankarms like this, or would I need a whole new chainset/crankset as others have said?

Thanks.

EDIT

Just to clarrify when I say "I can fix it" I mean I can fix it using new crank arms and not a whole new chainset being needed. I probably won't fit due to a lack of understanding on bike.

[Cycling_Man]

The fix your bike voucher would give you £50 towards a repair. i think this is the best way forward in your circumstance.

That is what I was thinking too.

I am planning on taking it to a place for them to have a look at either tomorrow or the next day and see what they say. I wanted to ask you a question quick. You said that the Chainset was toast but another user said that I could get this fixed with new crankarms and linked some that looked like they would work. If that is right it would probably be a lot cheaper than having to buy a whole new chainset so was wondering why you think a new chainset is required? Is it not possible to resolve this issue with new crank arms.

Thanks for taking the time to help, Cycling_Man.

[jimlews]

Assuming that your existing cranks are mounted on a square taper bottom bracket axle and the "toast" crank is 170mm length, you should only need to replace the R/H crank arm.

Another things to bare in mind is the length of your existing bottom bracket axle. The Spa cycles link says that the (new) crankset needs an axle that is 110 mm , check that yours is that length.

If you intend to do the job yourself, be aware that you will need several specialist bike tools, and the knowledge of their correct use. It may well be cheaper and safer in the short term for you to take the bike to a bike mechanic.

[slowster]

It should be possible to transfer the chainrings to a new crank arm, but:

1. The bolt circle diameter (BCD) of the new crank arm must be the same. I cannot say for certain looking at the photographs, but I suspect that the BCD of your existing crank and chainrings is 110mm, which is probably the most common size (and is the size of the Spa crank linked to above).

2. All too often bikes are assembled with insufficient or no grease/anti-seize compound, and failure to do so when mounting chainrings on cranks is not uncommon. That can make it very difficult to undo the bolts holding the chainrings on, and can be another reason for going to a bike shop, which is more likely to have the right/better tools and the experience/knowledge to do the task.

If you know what you are doing, and bolts are not seized because the bike was properly assembled, it's not a particularly difficult task. If you don't know what you are doing, and/or don't have the right tools, leave it to a bike shop.

Explanation of BCD - https://sheldonbrown.com/measure-bcd.html

Crank fitting/removal - https://www.parktool.com/blog/repair-he ... hree-piece

Pedal fitting/removal - https://www.parktool.com/blog/repair-he ... nd-removal

Lastly, as jimlews has pointed out above, bottom bracket axle lengths also vary, and the Spa cranks are designed for a 110mm length axle if used as a triple chainset. In your case you would not use third inner ring position and you would only be using the chainset as a double, and consequently would need a shorter bottom bracket axle, probably 107mm. If your current axle is significantly different in length, it will affect front derailleur shifts, possibly so much that the front derailleur will no longer work. Unless you know what your current axle length is, e.g. by reference to the manufacturer's specifications for the bike or the chainset, the only way to find it out is to take the crank(s) off the axle and then measure the axle length. In other words, it would be risky to buy the Spa chainset without first finding out what your bike's current axle length is, and what the BCD is of your chainrings.

In short, there are a number of variables involved in fixing the problem. They are not rocket science, but if you don't know what you are doing or buy the wrong product, it's very easy to make a mistake which will cost you more money.

[Cycling_Man]

Assuming that your existing cranks are mounted on a square taper bottom bracket axle and the "toast" crank is 170mm length, you should only need to replace the R/H crank arm.

Another things to bare in mind is the length of your existing bottom bracket axle. The Spa cycles link says that the (new) crankset needs an axle that is 110 mm , check that yours is that length.

If you intend to do the job yourself, be aware that you will need several specialist bike tools, and the knowledge of their correct use. It may well be cheaper and safer in the short term for you to take the bike to a bike mechanic.

How do I figure out if I have a square taper bottom bracket axel and how do I fiture out the length of axel. I looked under the bike near the chainset and it has these stampped onto it; "ADC8E00524" and "B (or an 8, not sure) - 1582BR. I'm guessing this is the number talking about the bottom bracket. Only beause it is BR and in my mind that means "Bottom Bracket" but I don't know haha. If so then would these not fit because it says 158, which I am guessing is 158mm. I have already looked and the length on the crank arms and it is 170mm but not sure on the square bottom bracket axle but maybe you know from what I have described. I don't know much about bikes so if you could explain it to someone who is a novice that would be great thanks haha.

I looked at the cranks length on the bike and they are 170mm I believe. On the inside of the crankarms it says "170UA01" believing me to think these are 170mm cranks but could be wrong. I just need to know if the bike i have has a square taper bottom bracket axle but not sure how I figure this out.

Thanks, Cycling_Man

[Cycling_Man]

It should be possible to transfer the chainrings to a new crank arm, but:

1. The bolt circle diameter (BCD) of the new crank arm must be the same. I cannot say for certain looking at the photographs, but I suspect that the BCD of your existing crank and chainrings is 110mm, which is probably the most common size (and is the size of the Spa crank linked to above).

2. All too often bikes are assembled with insufficient or no grease/anti-seize compound, and failure to do so when mounting chainrings on cranks is not uncommon. That can make it very difficult to undo the bolts holding the chainrings on, and can be another reason for going to a bike shop, which is more likely to have the right/better tools and the experience/knowledge to do the task.

If you know what you are doing, and bolts are not seized because the bike was properly assembled, it's not a particularly difficult task. If you don't know what you are doing, and/or don't have the right tools, leave it to a bike shop.

Explanation of BCD - https://sheldonbrown.com/measure-bcd.html

Crank fitting/removal - https://www.parktool.com/blog/repair-he ... hree-piece

Pedal fitting/removal - https://www.parktool.com/blog/repair-he ... nd-removal

Lastly, as jimlews has pointed out above, bottom bracket axle lengths also vary, and the Spa cranks are designed for a 110mm length axle if used as a triple chainset. In your case you would not use third inner ring position and you would only be using the chainset as a double, and consequently would need a shorter bottom bracket axle, probably 107mm. If your current axle is significantly different in length, it will affect front derailleur shifts, possibly so much that the front derailleur will no longer work. Unless you know what your current axle length is, e.g. by reference to the manufacturer's specifications for the bike or the chainset, the only way to find it out is to take the crank(s) off the axle and then measure the axle length. In other words, it would be risky to buy the Spa chainset without first finding out what your bike's current axle length is, and what the BCD is of your chainrings.

In short, there are a number of variables involved in fixing the problem. They are not rocket science, but if you don't know what you are doing or buy the wrong product, it's very easy to make a mistake which will cost you more money.

Thanks for replying and giving some adivce and useful links. I don't think I will try to fix this myself since I don't know much about bikes so it might be a little tricky. I just wanted to know if this would require me to buy a whole new chainset with new cranks and everything or if I can just change the cranks themselves. Would you happent to know this.

If it helps I looked at the bike and I have a few details.

The Writing Stamped On The Inner Crank Arm - 170UA01
The Writing under what I believe to be the bottom bracket - "ADC8E00524" and "B (or an 8, not sure) - 1582B

Thanks, Cycling_Man

[slowster]

Thanks for replying and giving some adivce and useful links. I don't think I will try to fix this myself since I don't know much about bikes so it might be a little tricky. I just wanted to know if this would require me to buy a whole new chainset with new cranks and everything or if I can just change the cranks themselves. Would you happent to know this.

As I said, it should be possible to transfer the chainrings to a new crank arm, provided the new crank arm which you buy or which the bike shop sells has the same bolt circle diameter (BCD), and providing the bolts can be undone/are not completely seized.

[Cycling_Man]

Thanks for replying and giving some adivce and useful links. I don't think I will try to fix this myself since I don't know much about bikes so it might be a little tricky. I just wanted to know if this would require me to buy a whole new chainset with new cranks and everything or if I can just change the cranks themselves. Would you happent to know this.

As I said, it should be possible to transfer the chainrings to a new crank arm, provided the new crank arm which you buy or which the bike shop sells has the same bolt circle diameter (BCD), and providing the bolts can be undone/are not completely seized.

Ok I see. I just didn't know if the make of chainset I had didn't allow for this. Sorry if I am sounding dumb or if you are having to repeat yourself haha. Thanks for your help. I will take it to a shop / ask what they think and then I will report back on the thread probably to see haha.

Thanks for your help, Cycling_Man