What length square taper axle do I need?

[@BikeGremlinUS]

EDIT 2024: If you have any questions, please use the BikeGremlin forum (I try to respond to every comment, but KZbin sucks at notifications, especially when it comes to any follow-up questions): www.bikegremlin.net/ Here is a better explanation (with a drawing) of the difference between the ISO and JIS taper standards: bike.bikegremlin.com/1634/bicycle-bottom-bracket-standards-explained/#jis-vs-iso Relja

[@MrBuzzgrow]

Very helpful content and well explained. I was fitting BB this morning and couldn't find length explained. Thank you. I was fitting Sunrace FCM300 on 118mm VP bottom bracket and it pretty much worked well. As you mentioned 122 would probably be good choice as well.

[@weeringjohnny]

Very clearly explained in a language which is not his own. Good job!

[@xxTosteRxx]

I am changing cranks on a bike and every part of it is from different bin. I felt lost but you made it all perfectly clear thanks man.

[@BikeGremlinUS]

Cool - glad to hear that. :)

[@peterjurczyk61]

Thank you for your expert instruction...just perfect for sizing appreciated quite sure I will order the right part...Thank you hope your well have super evening....

[@jimflammer9370]

I have been looking for a video like this.

[@Inverted_NL]

Exactly what i need! Thank you

[@jaycahow4667]

Here are some comments from over 45 years of working on bikes. You can check your chain line by looking backwards through the gap between your chain rings at the cluster. Another way is to slide a stiff metal yard stick between the chain rings and lay the back end of the yard stick on the cluster. I have a number of older bikes (road and mountain) that still use tapered cranks. I long ago dumped all their original bottom brackets and replaced them with Phil Wood Sealed Cartridge Tapered Bottom Brackets and their associated Cups. While these are expensive you cannot purchase a better looking and operating tapered bottom bracket and they literally last for decades. They come in all style tapers, axle lengths and threads to fit any model frame and crankset. Their proprietary Cups use a special wrench and actually totally thread into the bottom shell from both sides and grab the cartridge allowing the cartridge to be moved back and forth somewhat to finis your chain line when installing. They last for ever and can be rebuilt for minimal cost by the factory. They also have longer tapers on their axles which allows reuse of cranksets that are bottoming out on regular tapered axles (which can happen after to many removals and installs). I have some that are 40 years old and still working and they spin better the more they are used without any play. I cannot recommend them enough other than the initial costs (cartridge, cups, and wrench over $200) but they are literally a set and forget item which pays off in the long run as little or no maintenance. www.philwood.com

[@BikeGremlinUS]

Great points. From my perspective - Europe, Serbia: Phill Wood BBs are difficult to source, and cost almost as much as half of my countrymen earn per month. Shimano square taper BBs cost about $12 to $15 and often last for a decade (depending on mileage and riding conditions). Relja

[@KarlosEPM]

Cool vid. I believe I have read your article on chain line, good stuff too. Chain linen can further be affected by how much you tighten the crank arms into the BB axle, but newer Shimano BBs have a disc at a determined portion of the axle (drive side only) and call it something like chain line keeper.

[@KarlosEPM]

I would like to ask you something regarding ball bearings. I recently acquired a bike with Shimano 105 wheel hubs (1055 series, from the 90s) and want to overhaul them. However, I find online that one can purchase carbon steel as well as stainless steel ball bearings. The hubs in question aren't listed as compatible with either of the two, maybe because of their age. Which would you recommend? (And why?) FWIW the bike will mostly be ridden in Belgium, so hitting pot holes is a real danger. Thanks in advance!

[@BikeGremlinUS]

Hi Carlos, I don't use stainless steel. Bearing balls are well protected from water/rust by the grease in the hub. As far as I know, when rusting is not a problem, carbon steel bearings last longer compared to similar-quality stainless steel ones. My article on bicycle bearing balls: bike.bikegremlin.com/2255/standard-bicycle-bearing-ball-sizes/

[@KarlosEPM]

@@BikeGremlinUS Wow, thanks for such quick reply. I appreciate your advice, have a great evening!

[@mikeharvey9811]

Very clear, thank you so much. Mike in Bristol Uk

[@jimmytorpedo6690]

Good video, thanks!

[@raio_omega]

Nice ! thank you to help me !

[@Soapmctowelish]

nice informative vid! thanks

[@TheSpeegy]

Very helpful, thanks. Just in the process of deciding on the right size. I had 2, one of 122.5 which worked, but there was too much space and made gear changing "clunky". I fitted my spare, which is 110, but now the smaller gear is only about 0.5mm from the frame, even with a small spacer added (although gear changing is excellent".). Think I actually need something like 113 or 116.

[@artoutlawphoto]

this is the follow up video that Simion from GCN did not include in the video Bottom Bracket Standards Explained, he was to tired to explain how many bottom brackets "Standards" are there.

[@BikeGremlinUS]

OVER 9000!!!! :)

[@rafriedman]

Excellent video! I just pulled the bb from a Zizzo folding bike with one ring (I’m upgrading to a double) and it 120mm! Maybe there was a supply chain issue?

[@BikeGremlinUS]

Could be. Most modern square taper cranks fit the JIS taper standard and I would look for a 117 ~ 118 mm Shimano bottom bracket as a replacement for that one.

[@rafriedman]

@@BikeGremlinUS Sounds right! Thanks!

[@deltafour1212]

I have an odd size threaded squared tapered bottom bracket that is hard to find 68 x 119 Closes I come is 68 x 118 & 68 x 120. Which size would you recommend.

[@BikeGremlinUS]

Hi, If the search of bike.bikegremlin.com website doesn't provide a satisfactory answer, please post the question on the bikegremlin.net forum, so that the answer(s) can be easily searched and help everyone else with the similar dilemma. Relja

[@mzr.johnny]

Can I use 68mm in 73mm shell? (square bottom bracket)

[@BikeGremlinUS]

Hi, Please use the BikeGremlin forum for technical questions: www.bikegremlin.net/ Relja

[@randy1817]

On a Shimano un300 BB, does the inside of the crank seat up against the chain stabilizer collar?

[@BikeGremlinUS]

Hi, Please use the BikeGremlin forum for questions - it also allows easy picture uploads (when needed): www.bikegremlin.net/ Relja

[@Tuan6969]

I have 7 gears at the back and want to convert to 1x chainring, how long do i need for it ?

[@BikeGremlinUS]

Hi, Please use the BikeGremlin forum for questions: www.bikegremlin.net/ Relja

[@zsoltmarosi7546]

question! how do I confirm that my BB has a 24TPI or 26TPI thread? the bike in question is an old BSA made in late 80's and desperatly wants an upgrade from cup & cone to sealed bearings. THANKS

[@BikeGremlinUS]

Measuring the BB shell’s width can be telling. Common diameters and shell widths: bike.bikegremlin.com/1634/bicycle-bottom-bracket-standards-explained/#3 Also, besides counting, there is a tool for measuring the pitch: www.amazon.com/Grip-Thread-Pitch-Gauge-SAE/dp/B004ROIU2A

[@luigiprovencher]

What happens if you can't find the length you need? I've got a 125mm that seems to be an odd ball size.

[@BikeGremlinUS]

I look for the closest match in that case. 123 and 128 are more common lengths. The choice depends on the desired chainline, drivetrain usage (large vs small chainring usage) and FD cage movement range. Relja

[@luigiprovencher]

@@BikeGremlinUS This is off a BCA SC29 Mountain Bike. A POS in my opinion. The fixed cup of the bottle bracket is so frozen onto the frame it's not even funny. Been trying for at least a week if not more to get it off so that I can replace it to no avail. Rounded it off with the spanning tool and am now trying the unorthodox methods found on here and haven't had any luck yet.

[@BikeGremlinUS]

If it’s an aluminium frame, BB cups can seize so the removal is not possible without damaging the frame’s threads. :(

[@luigiprovencher]

@@BikeGremlinUS Figures. Yeah. It's an aluminum frame.

[@BikeGremlinUS]

Try this: Put the bb tool in a vice. Put the frame on the tool. Improvise some washers and a rod to keep the frame pressed/engaged on the tool. Use a heat gun with up to 180 C temperature on the BB shell. Try turning the frame to unscrew. Over the past decades, I came across a few frames where even that would not help. If it works, a thread chasing tool will be needed to clean the threads. If the threads are British standard, and they get ruined beyond repair, you can cut new Itslian standard threads. Use anti seize paste on all threads that are aluminium-steel combination. kzbin.info/www/bejne/jpOaf3iYmJimi6ssi=rAeK3u8MgBlkeoUN

[@loonation2185]

hello, i have a problem with my new crankset that i bought, it seems that the square holes of it is much bigger than my old one as it just slides through to the entire length of the spindle, for reference my current bb spindle length is only 103mm which works well with my old crankset, does crankset square hole sizes differ too?

[@BikeGremlinUS]

There are two different standards for the square taper spline shape: ISO and JIS. If your new cranks are made to match JIS standard, and your axle is machinet to ISO, it's normal for the cranks to "climb" higher. The simplest solution would be to find a Shimano cartridge square taper bottom bracket - as most modern cranks are built to JIS standard (Shimano and the likes). A bit more details on ISO vs JIS: bike.bikegremlin.com/1634/bicycle-bottom-bracket-standards-explained/#jis-vs-iso Also, depending on your cranks model and type, a new JIS-standard BB spindle may require a 110 or longer axle length in order to achieve the same chainline as before. More about chainline (chapter 6 deals with square taper axle lengths): bike.bikegremlin.com/1755/bicycle-chainline/

[@loonation2185]

@@BikeGremlinUS thank you very much

[@anonymously241]

R you Turkish?

[@BikeGremlinUS]

No. :) www.bikegremlin.com/about/

[@YT-Science]

i changed bracket and it say for 115 mm, but my spindle is 127 mm, what will happen?

[@BikeGremlinUS]

It will affect the chainline. Article on that: bike.bikegremlin.com/1755/bicycle-chainline/

[@everettbugg1443]

You did an excellent job! I have rebuilt a few bikes, perhaps 60 or so and I am considering moving an old Giant Perigee to a triple crankset using a bit longer bottom bracket. The original BB for a double Shimano Biopace crankset measured 116mm but I’m only going to move up to 118mm and see how much clearance is present. I wish I had looked at the clearance before I pulled the crankset but it won’t take long to reinstall and check the spacing. 118mm was a frequently given length for a triple crankset on the Harris Cyclery (Sheldon Brown) webpage. Thank you for making this video sir!

[@romanmentor9238]

I am having a Shimano triple in the front.The older bb was 120mm.I don't understand,they don't produce it nowadays? I neee to choose only between 122.5 and 117.5mm?

[@BikeGremlinUS]

It seems so. 122~123 mm is usually good with trekking/MTB triples paired with matching derailleurs. 117~118 mm usually works better with triple road derailleurs.

[@romanmentor9238]

@@BikeGremlinUS It's 48-38-28 teeth so more hybrid than mtb.I've tried 127.5mm the front derailleur couldn't put the chain on the largest chainring,no matter how I adjust it

[@BikeGremlinUS]

Yup, 127~128 is too long. 122~123 should be good.

[@seanmelvin5115]

Hello all. I have a bike with a M48 Bottom Bracket. I want to upgrade my drive train to shimano xt. The xt BB is obviously smaller so I’m wondering if they make some type of thread in step down or if another option is available?

[@BikeGremlinUS]

I haven’t seen that standard, so don’t have any ideas. :(

[@leftywedge]

Hello. Thanks for this explanation. It was helpful. I do have a situation with my bottom bracket and chainrings. My BB is a 115mm length (68mm) with a triple chainrings and unable to shift to the small chainring because my front derailleur (clamp on) butts against the seat post and therefore does not have the proper spacing. After listening to your information, I should consider a 122mm BB. For which I assume it will push the chainrings further away from the frame. Is that correct? The difference of 7mm between the 115mm and 122mm , is that split equally on both side of the frame? Thanks for your time.

[@BikeGremlinUS]

Hi, Short answer: If I had to bet, and/or were able to buy only one-size BB for testing, I'd give the 122 mm a go with a triple crank. Longer answer: I usually have all sizes at hand and can afford a bit of trial and error, but I always first try with the size I expect to be the right one most likely (122 mm for Shimano triple cranks). The length is not split evenly for every size. Picture 11 and the chart below it in chapter 6 of this article show how the length is "distributed" on each side: bike.bikegremlin.com/1755/bicycle-chainline/#6

[@ГеннадийРутковский]

смотрел как глухонемой --поучительно но жаль што ты на РУССКОМ не базаришь .

[@BikeGremlinUS]

Только сербско-хорватский: :) www.youtube.com/@BikeGremlinRS Relja Edit: Settings -> Subtitles -> Auto-translate -> Russian