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Bottom bracket replacement

Hello, I have a bike with CDN gates belt and alfine 11 gear hub. I had to replace bottom bracket twice during 5000km is that normal? It uses BSA 68-120mm thun zumba jis:

https://www.google.com/search?q=BB+THUN+ZUMBA+GBL+440+BSA+JIS+Urban&rlz=...

which is really not standard and I am struggling to find some quality alternative to this.

Can you suggest me something? Money is no object:)) bun not much more than 100-150 USD:))

Also can this be fixed with something more standard like 68-118 and use some washers or something?

Thanks.

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12 comments

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Secret_squirrel | 1 year ago
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Double check the spindle length with calipers, and also confirm its symettrical in the frame.

There is a lot more choice at 119mm and you can usually offset it in the shell to get the extra 1mm if needed, if you choose a BB with a flangeless non-drive side cup.  1mm of Q factor wont make any difference and clearance will probably be unaffected.

Royce, Phil Wood and Stronglight do a 119mm JIS that should work and the more expensive ones will have massive warantees on them.

royceuk.co.uk

Otherwise have a post on Retrobike.co.uk and get a quality used or new old stock one.  There'll be some one with a hundred of them in their shed.

Looks like  Campy did 120mm JIS bb's at some point too.

 

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Morignus replied to Secret_squirrel | 1 year ago
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Hi,

thanks for the advice, it is exactly 120mm so I guess the 119 would be best option

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Morignus | 1 year ago
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I have found this one: https://www.amazon.com/OMNI-Racer-LIGHTEST-Cromoly-Ceramic/dp/B08ZC2CM32... but don´t know manufacturer

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IanMSpencer | 1 year ago
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Those type BBs are pretty standard on cheap bikes, but they went out on quality bikes 20 years ago. That one you link to is likely to just be any old Chinese made version that they've bought a heap of.

I had good experience with SunRace BBs. The "tech" such as it is is similar across all brands, there is a BB width and a spindle size, (threads all seem to be "British").

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Drinfinity replied to IanMSpencer | 1 year ago
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Token do some good square taper bottom brackets, I have three on the family Islabikes. The bearings needed to be replaced after a couple of seasons of cyclocross abuse, but that's to be expected.

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Morignus replied to IanMSpencer | 1 year ago
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Thanks for the tip. I will try to find 68-120 from SunRace or Token and if not found I will give it a go with 68-118 potecially using washers.

I have found one with correct diameters on Amazon: https://www.amazon.de/-/cs/gp/product/B07V6YLWJK/ref=ppx_yo_dt_b_asin_ti...

so I will try that one too.

I was suprised that Canyon use this BB but I have looked at the Gates instruction and they recomended for CDN belts but they say that CDN belts are designed for low-milage commuting.

Perhaps I will consider to convert it do CDX or even CDX:EXP belt.

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HoarseMann | 1 year ago
2 likes

I'd also make sure the belt is not too tight. I can imagine there's not much margin in getting the tension just right. An over tensioned belt won't skip, but will likely place undesirable loads on the BB.

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Morignus replied to HoarseMann | 1 year ago
1 like

Thanks, I've just ordered the tension meter from gates as I do not fully believe that the mobile app is precise

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bobbinogs | 1 year ago
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How long consummables last on a bike are a bit like the 'how long is a piece of string' question.  There are a lot of factors that come into play like how you might clean your bike (jet wash, etc.) and the weather you ride your bike in...and the dust/sand around on the roads.  I haven't any belt drive experience but get through an Ultegra threaded BB on a normal road bike every ~18 months...but that is on the winter bike after ~8,000km. 

Is your bike an e-bike?  I am not sure how that affects things.

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Morignus replied to bobbinogs | 1 year ago
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Hello, no, it's not a ebike, it is Canyon Commuter 7: https://www.canyon.com/cs-cz/hybridni-kola/commuter-kola/commuter/commut... I ride it for work all year about 25 miles a day thru mixed terrain mostly gravel and pavement but couple miles thru forest road. So there is a lot of mud half a year. That is one of the reason I got a bike with belt.

And I do not wash it with preasure washer, only normal hose.

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huntswheelers | 1 year ago
3 likes

Hey.... I feel your pain, I have a customer with a Cube Hyde Hybrid on Alfine 8 with CDN belt. Over the past 3 years we've been through many many bottom brackets. The Thun BB's are decent but my customer is a runner too and very heavy footed and a grinder on the gears.....we've tried XLC, Shimano, VP and other brands mainly for Dutch bikes, which take a pasting weather wise.....but the best we have used and currently in use is an FSA Power Pro bottom bracket which are advertised as "oversize balls" in the bearings and has been in use for 6 months now. This guy rides 15,000 miles annually on this bike, hence no chain and hub gears as his choice. I opt for a 118mm or closest for him, the belt drive does kind of allow a bit of flexibility on the "chain line" of a millimetre or so. Hope this helps

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Morignus replied to huntswheelers | 1 year ago
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Hello,

thanks for the advice, I will try to find it but there is another problem, all the bike shop has 0 stock levels  7

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