Shimano Hollowtech II Bottom Bracket Installation - BB-MT800

If you need to install a Shimano Hollowtech II BSA threaded bottom bracket, this video shows you how to do it, along with the tools needed and hints & tips.
The BB installed is a BB-MT800 for MTB use, which uses a smaller diameter Hollowtech II cup tool, the Shimano TL-FC37.
Check out our website for workshop info, Swiftwick socks, bikepacking products and more: www.vanguardcycles.com
Please get in touch and let us know what other workshop jobs you'd like us to cover!
Chapters:
0:00 - Welcome!
0:32 - Tools needed
2:48 - BB-MT800 Overview
4:48 - BB shell width measurement
5:32 - Drive-side installation
9:21 - Non-drive-side installation
11:17 - Cleanup
Sponsored Amazon links to tools and parts:
Shimano BB-MT800 bottom bracket: amzn.to/3IktJjN
Shimano TL-FC37 cup tool for MT800 BBs: amzn.to/3xdD0Up
Park Tool BBT-59.3 cup tool for MT800 BBs: amzn.to/3K4tN8A
Park Tool TW--62 bi-directional torque wrench: amzn.to/3IjD3Ev
Park Tool TW--2.2 beam torque wrench: amzn.to/3luwZA1
Moore & Wright digital vernier caliper: amzn.to/3E1tp6X
Sealey mini grease gun: amzn.to/3K32xHw
Mobil XHP-222 grease: amzn.to/3E1OePk
SATA 3/8" Ratchet handle: amzn.to/3YkT8yO
Adapter set: amzn.to/3HWdXes
Muc-Off high pressure degreaser for pre-installation cleaning: amzn.to/3YLP8ru
Finish Line absorbent mat: amzn.to/3jw8nGp
Yeti rambler mug: amzn.to/3HUPAg3
The above are affiliate links, which means we receive a small commission if you go ahead and make a purchase. The main purpose is to help you find the tools and parts you might need to carry out the job, but if you do make a purchase through a link, thank you very much for your support!
Shimano technical information: si.shimano.com
Park Tool bottom bracket tool finder: www.parktool.com/en-int/categ...

[@Harari_]

I never changed a bottom bracket and I was sure that It’s easy and I know how to do it. I was right, it is very easy, but it’s one of those videos that you are watching just to b sure that u r doing it correctly and I love them. This video showed EVERYTHING that u need to know and covered every little step that someone might just want to b sure about before he’s going to the next step even if he is 99% sure that he done that right. LOVE IT.

[@vanguardcycles]

I'm so glad! I really try to give as much information as possible, really happy it was helpful and well done on doing it yourself 😀

[@bs2592]

My sons crank is very wobbly. Does it mean the BB is broken or just needs tightening? Also, where do I get the tightening tool from?

[@ReValveiT_01]

The tool costs 35% MORE than the BB itself. Brilliant.

[@vanguardcycles]

Other (cheaper) tools are available for sure. It's often a good idea to pool funds with friends or local club members and collectively buy quality kit that will last for years for common jobs like this.

[@thawnhatzaw2343]

Super helpful video that covered everything you need to know. Thanks a lot. I took apart and serviced my BB using this video and others on youtube (Park tool, made to cycle and made good bikes). It went smoothly and was easier than I thought. Keep making videos they're very helpful for budding home mechanics!

[@vanguardcycles]

Really glad it helped! Also if there are any other topics you'd like to see us cover, please let us know 😀

[@dominicpayne4393]

Thank you so much dude. Much appreciated

[@bigpimpinbig1]

Best video out there. Thanks for the great details. Decided to invest in a decent torque wrench for this. I wouldn't have thought of getting one that can measure torque counter clockwise without you mentioning it! It really helps you mentioning the tools in the description - e.g. the adapters for the BB tool.

[@vanguardcycles]

So glad it helped out - my motto is that every day is a learning day :) Are there any other jobs or tech you'd like us to cover in the future? Ride safe!

[@bluetooth2000]

That's rocket science!

[@Blades-fm6ck]

Quality video, clear explanation, cheers

[@vanguardcycles]

Glad it helped 😃

[@julioscioville2308]

Excellent

[@vanguardcycles]

Thanka very much 😀

[@RosClan97]

thank you!

[@vanguardcycles]

You're welcome! 😀

[@khadijakhair591]

Good thank you

[@vanguardcycles]

You're welcome!

[@charliepizarro9450]

This gives me the confidence to tackle it myself. One question: my crankset specs show two figures for bottom bracket shell width: 68mm and 73mm. Does this mean there's a range? I'm replacing an existing BB with the same one, so I'll replicate the two spacers already on there, but I'd like to understand the numbers. Thanks for this excellent guide to the process.

[@vanguardcycles]

Really glad to have helped! You're quite right about the sizing. If you check the BB Dealer Manual, for example - si.shimano.com/en/pdfs/dm/MDFC001/DM-MDFC001.pdf - you'll see on page 11 the spacer setup is illustrated. Let me know if you need any more advice 😀

[@charliepizarro9450]

​@@vanguardcycles So they're saying that BBs generally come in two widths, and they're giving you info for both. Now I understand why we should measure. Makes perfect sense! Thanks from Oakland, California, for your excellent video!

[@vanguardcycles]

Yep that's right. Well, in fact cranksets and bottom brackets come in lots of different widths, so it's always best to measure. I'd also say if you're working on a used bike, it's always worth checking the setup with spacers etc, as they aren't always installed correctly!

[@sufyanm4661]

When tf did they change the tool and why is it so hard to find the right tool without videos like this. I’ve been using Shimano bbs for years and now all of a sudden my bb wrench is useless so I have to wait 3 more days and pay more shipping to replace my seized BB. Nice one shimano

[@vanguardcycles]

I know, it's really annoying. There's also a different tool for road Dura-Ace too!

[@sufyanm4661]

@@vanguardcycles ah well, I caved and bought an adapter, at least I have a spare bike for now, but I was planning to go for a ride tomorrow haha. First world problems

[@namdarbolour9890]

Does greasing the threads defeat the purpose of the white compound we see pre-applied at the factory on the threads of the bearings?!

[@vanguardcycles]

That's a good point. Whilst things like factory-applied thread lock can help prevent corrosion, in real life a good coating of quality grease or anti-seize is much better. The cups are torqued so high in the frame that they are very unlikely to loosen. In addition, in British threaded (BSA) frames the thread direction coupled with the precession gives a "self-tightening" effect. The key is to prevent the cups seizing, especially if you have a steel frame.

[@stevebennett3587]

Can i run this bottom bracket with my shimano M5100 deore crankset🤔and if so, what spacers would i need for 12x148 boost spacing on a 1x10 deore set up please sir👍

[@vanguardcycles]

The spacers you need depend on the width of the bottom bracket shell (of the frame). Your crankset works with this BB, but the cranks need to be the 148 Boost version if that's your setup.

[@Gleeleeglee]

On video you had L and R cups opposite of the plastic tube? 3:30

[@vanguardcycles]

Aha well spotted! I had taken it apart so many times for the video but I didn't re-shoot the footage 😀

[@SgtJoeSmith]

thats what i just noticed too

[@gregmoxham2120]

@@SgtJoeSmith They are interchangeable but you're right, they were switched. They didn't go in the bike like that, even though it shouldn't make any difference. Good spot!

[@shaknit]

I have an old trek navigator and the bottom bracket measures out to be 73x116mm cant seem to find any that size. Any suggestions.

[@vanguardcycles]

I guess you mean it's a square taper BB? (rather than something like Octalink). Shimano make a 73x118 BB-UN300 which may well be OK, it will probably make very little (or no) difference to the chainline. If it's a case of installing that vs. writing off the bike, I'd go for it. Hope that helps?

[@Gleeleeglee]

Is the threaded part of the mt800 aluminum/plastic?

[@vanguardcycles]

The cups are aluminium

[@Mrpablotortas]

what's the difference between BB-MT800a and BB-MT501 beside the installation tool?

[@vanguardcycles]

The BB-MT800 is an XT level part, with better quality sealed bearings. The 501 is Deore level. Hope that helps!

[@8bitoperator]

Since the base of this grease is lithium, can it react with aluminum? I meant Mobilgrease XHP 222

[@vanguardcycles]

Quite genuinely in this application, and with a quality stable grease, it really isn't an issue at all. However you could also use a copper anti-seize or something like Park Tool ASC-1, which I believe is aluminium-based.

[@bonifacioivcomilang1038]

Hi good evening do have a video of how to remove the bearing fron the bb?know the size of the bearing?

[@vanguardcycles]

Hiya! Unfortunately Shimano specifically state that the bearings shouldn't be removed from their BB cups, so I don't have that info.

[@AnotherMrLizard]

They’re integrated into the cup on most. Get a hope 24mm bb then it’s just 2 mr2437 each time.

[@chiefengineer6288]

a good video will show the dissasembly as well. Good video it you buy a bike without a crank....

[@vanguardcycles]

Ah we've got videos showing both removal and installation of HTII cranks on the channel. Removal is here: kzbin.info/www/bejne/iKPHp5x_ebZ_hKc Assembly is here: kzbin.info/www/bejne/h52ZknmZhc6JetE Hope this helps!

[@chacmool2581]

Is the width of BB cups the same between Road and MTB?

[@AnotherMrLizard]

For shimano no they are slightly different.

[@victorromarioholguinoquisp545]

What is the width of the BB-MT800?

[@vanguardcycles]

It's for 68mm and 73mm BB shell widths. You use the spacers to set it up, depending on your frame, as described in the Shimano Dealer's Manual (DM): bike.shimano.com/en-EU/product/component/deorext-m8000/BB-MT800.html