Daisads

Hi all,

could do with some advice on repairing my spin bike. In short the pedal hole on the crank arm has completely worn away therefore I need to need replace the whole crank arm itself. I have taken the nut off and exposed the bolt but I can see the thread (as in pic) is worn somewhat. I have bought all the tools, have install the crank arm puller part and got it in but when I start turning the lever (the other part on the crank puller) it only goes so far and then stops. Therefore I am unable to remove the crank arm and don’t know what to do next!?!?
any ideas?

HillRider

You can't post pictures until you have 10 or more postings. I'll assume you are pulling a common square taper crank arm with a "nutted" bottom bracket spindle and have removed the crank fixing nut and threaded in the puller. First, be sure there isn't as washer still in there. If not, the puller will indeed get tight as you turn the screw-press handle as it has got to generate a lot of force to pull the crank arm. They are on there very tight if installed correctly. If the outer part is threaded fully into the crank arm, just keep turning the handle and the arm will indeed pop off.

Daisads

huge thanks for your prompt reply. How tight does the puller have to go in then? As I have put it in as much as I can and then I presume need to use a adjustable spanner to screw in even further? How many threads should be showing? Also is it right that I just removed the crank nut and there is still a spindle showing?
why is the handle not turning then when I don’t hAve the puller in far enough?
thanks again! Legend.
Dave

dsbrantjr

Most pullers have an outer threaded part which has to be screwed into the threaded opening in the crank arm, and an inner threaded screw which drives against the spindle to drive the arm off of its tapered mount. First back the screw part out of the outer part or even remove it. Make certain that there is not a washer left in the crank arm. Then screw the outer part as far as you can by hand, it should come to a firm stop after a few turns, don't stop until it is firmly seated to avoid stripping the threads. Then put the screw part back in and turn it until you meet resistance; it is now bearing upon the end of the crank. Now turn farther to force the crank arm off of the taper, it will likely take a good amount of force with a wrench if the inner part does not have a handle. At some point the arm will come free of its taper and you can back out the screw and remove the tool from the arm.
Here is an article with some photos from a trusted source, I find it better than YouTube videos: https://www.sheldonbrown.com/tooltips/cotterless.html

Daisads

Hi all, huge thanks for your advice, very helpful. From your comments seems I didn’t have the puller in enough, meaning I had to hammer the lever around three more times and then it came loose and off!!!! Brilliant. Now I can’t get the crank puller out of the old crank arm, it’s jammed in... any ideas bar good old wd40? Thanks again!

JoeTBM 

Try looking at this video

Miele Man

There should be a flat surface where you can put a wrench to unscrew the main body of the crank puller. It'll be on the part that you first threaded onto the crankarm.

Cheers

Daisads

Thanks for all your help. I have now done it. Have a good day.

Barry2 

Note: when purchasing a new crank arm, be sure to purchase one of correct length.
Those tapered square holes are not all the same either.
You might do well taking it to a store for help in getting the correct replacement or the bikes manufacturer.

Barry

Daisads

Hi all, I have tried three retailers inc Amazon to get a replacement Crank Arm and every single one has been too heavy and the square tapered hole is too big! I know it’s a 170mm In length but is there anyway of categorising the right one? I am told what I have is an Alloy crank arm for a spin/exercise bike. I have asked the retailer I bought it from but their communication has been non existent!! All the ones I have bought seem to be heavy Aluminum, the one that I have is far lighter and less bulky.

any ideas? And if so where can I buy it??
i need a spin bike 170mm RIGHT crank arm.

Thanks!

Dave

p.s. Why are left crank arms so much easier to get than right!!!!????

Barry2 

Dave,
look at any bike pic, the right side crank arm is integral to the gears that drive the chain.
so as far as bike parts are concerned, only the left side is available as just an arm.

Some of our crank arms connect to a square tapered shaft. Problem is that there are several standards for “square taper” sizing.
The shaft dimensions vary by Brand and country.

Our crank arms are under huge stress. Think 200lb guy, stomping down on a crank with the bike not moving.
Because of the stress, you may find our cranks are heavier and over engineered.
I suspect a spin bike does not develope the same levels of resistance to that 200lb guy, and so cranks could be lighter.

Hade a generic crank worked for you, great. But it is possible the your square taper does not comply with one of our standards.
The spin bike manufacturer may be the only compatible replacement source.

your other chance may be to repair the arm you have. Threads in aluminum can be replaced using a “helicoil”.
The resulting repair is stronger than the original.
Problem is, it is costly to have done. You may need an engineering type friend you could bribe with beer and a home cooked meal.

If you still wish to pursue a bicycle crank as a replacement, you are going to need to accurately measure the square taper and the holes in the cranks you have.
If your taper is significantly smaller, it is unlikely to be a known bike standard.
you may find this interesting...https://sheldonbrown.com/bbtaper.html


I hope this helps

Barry

Daisads

Barry huge thanks for your detailed response.
ok so I could use the Helicoil and May try that but I am determined to get another crank arm. The problem i have is I bought the spin bike from UK sports imports and I am genuinely not sure what the brand of the bike is!!!! I have emailed them and asked them but so far nothing.
upon your advice I have measured the square tapered hole and on the crank arms I bought from Decathlon they are heavier and measure 2cm. On the crank arm I have the tapered hole is 1.5cm. The dilemma continues as I am sure the retailer won’t give me the dimensions of the hole!?
if you know anywhere then please recommend, your help is much appreciated.
if not then I’ll look at repairing the existing one, I never in a million years thought it would be that difficult to replace!!!

Thanks again Barry,

Dave

Barry2 

The photo shows the hole in one of my cranks.
~13.47mm across the flats on the larger inboard hole.
The smaller outboard hole is ~11.75mm
After all the hole is tapered.

These measurements are not totally accurate. Even an alternate manufacturers crank, designed to fit my Square Taper bottom bracket, may measure slightly different.

But if you original crank measures significantly different, then you likely don't have a regular bicycle standard for your spin bike Square Taper.

Barry2 

This thread is well worth a read
https://www.bikeforums.net/bicycle-m...saver-kit.html

Barry

DaddyCycle

In August 2020 I purchased a Sunny brand spin bike for exercise in my living room. This past summer of 2021, the original brake pad had turned black and started to make a loud squealing sound. I tried to find a factory-spec felt brake pad either made or endorsed by the original manufacturer, but after combing the web I had to settle for one on Amazon which measured as close as I could find (Abadoam brand).

The curvature of the replacement brake pad was slightly too narrow, but I’ve been able to “mold” it to the 40lb flywheel by keeping the brake knob at 100% pressure/stoppage when not in use. However, even six months later, the new pad doesn't make full contact when I'm biking, and still makes a lesser (but still annoying) squealing sound which I can only mitigate by fine adjustments to the brake pressure knob while exercising. While I can cope just fine using background noise from my TV or just putting in my earbuds, my wife dislikes the noise, and the dog desperately paws our back door in an effort to escape my cardio workouts. Any advice???

> Bike Model: Sunny Health & Fitness Spin Bike Belt Drive Indoor Cycling Bike with LCD Monitor, 40 lb Chrome Flywheel, 265 lb Max Weight - SF-B1423, Gray

> Replacement Brake Pad: Abaodam 2 Pcs Spinning Bike Brake Pads Professional Exercise Bike Felt Brake Pads Bicycle Caliper Brake Pad Hairy Pad Bike Brake Ground Fitness Bike P


Thanks!

JanMM

Your problem/issue has nothing to do with the topic of this sleeping resolved thread. I would suggest starting a new thread in this sub forum or in the Indoor and Stationary Cycling sub forum. (I have no idea how to fix your issue.)