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A riding buddy of mine has a new Shimano crankset (not 100% sure which).
When he shoves the spindle through his (old style - not the newer, smaller ones) BB cups, the free end comes up 5mm short of where it should to have the other crank push on and do up. The preload can't engage, the safety pin thing cannot either.
I've run older (5-10 year) cranks through both the new and old BB cups (I even had to mix and match for one ride due to a spannering cockup) and it went fine.
I'm left wondering if these newer cranksets have some kind of narrower recess for where they contact the BB faces - so the end he is shoving in first is actually being held away from the BB face by a part of the spider/crank.
I'm pretty sure Shimano have not changed the length of their spindles, but I could be wrong. There are extensive exploded diagrams available on the t'interwebz, but none I can see show useful stuff like actual real-world dimensions.
Any help gratefully accepted.
What sort of BB is it? Is it the right one. With press fit particularly there are a number of different sizes (widths). Sounds like the bb might be too wide?
This needs more information.
What frame & year.
What crank set and what length spindle.
What bottom bracket and how many spacers.
What changed in the system - did he replace just one part?
Saint cranks have a longer spindle (for 80mm bottom bracket?). Google seems to suggest some road cranks come in two spindle options 'for different sized seat tubes' but I don't trust anything that comes from AI on google.
Does your mate own a tape measure and/or camera phone?
Have Shimano created incompatibility?
Does the pope **** in the woods?
I don't know about crank axle lengths specifically but everything they ever do seems to involve a new 'standard', I hate it. I had to buy a special tool just to remove some XTR cranks the other day. A tool which fits only those cranks and which I will never need again.
I had to buy a special tool just to remove some XTR cranks the other day
an 8mm allen key?
Shimano have 3 axle lengths depending on the chain line required, everyone else has a standard crank axle and their chainrings are "boosted" to achieve the desired chain line.
Eg:
FC-M8100 - 142 or 148 O.L.D. (hub spacing) and a 52mm chain line
FC-M8120 - 148 boost spacing, 55mm chain line
FC-M8130 - 157 super boost spacing, 56.5mm chain line
The right crank with spindle determines the spacing, the left crank will work for any spindle.
Yes, but all the above fit the same BB. Some need spacers that come with the cranks, but all fit.
Shimano have 3 axle lengths depending on the chain line required, everyone else has a standard crank axle and their chainrings are “boosted” to achieve the desired chain line.
Eg:
FC-M8100 – 142 or 148 O.L.D. (hub spacing) and a 52mm chain line
FC-M8120 – 148 boost spacing, 55mm chain line
FC-M8130 – 157 super boost spacing, 56.5mm chain line
What I don't get is that even if you're the size of Shimano surely having such a large number of SKUs when you could achieve the same thing with fewer works against their own (and dealers/retailers) profitability. I had a direct mount and a band mount XT mech in my hand recently - they have a completely different top part whereas it would have been trivial to make one that could work either with a band or without.
I’m the riding buddy the OP is referring to.
Will try and keep this is brief and non-confusing as possible!
2 bikes: older Whyte T130 was running RF Turbine cranks with a Hope BB but as I was having issues with it I swapped to Shimano. Older style BB cups (wider diameter tool) with a borrowed XT 32t 8120 crank - running fine. 73mm BB shell.
Gen 1 Privateer with newer style XT BB (diff diameter tool needed) with Deore 12 spd crank in 73mm BB shell. Decided to buy new a XT 8100 crank - Deores came out and easy straight swap.
The issue arose when I put the Deore cranks in the Whyte - basically it was way too short so I can’t get the preloader in or obvs the plastic relocating tab. Thought I must have done something wrong but no, after measuring all cranks the older borrowed XT cranks have 120mm axles, the more recent Deores and the brand new XT which both fit the 141 are 115mm. Despite being told Shimano don’t do different axle lengths, they’re def different.
Happy the new XTs fit the 141 as intended but my plan to run the Deores on the Whyte hasn’t gone to plan.
There is a workaround (I think) - the Whyte has a BB mounted chain guide that’s roughly 5mm wide and a spacer on the NDS. Removing that spacer and using a narrower chain device means I might be ok with the shorter Deore. The 141 has ISG tabs so chain guide not an issue.
My mate will want his cranks XT cranks at some point plus the Deores are 30t and kinder to my legs if you’re wondering why I’m swapping them out!
A first world problem but not one I’d even thought would present itself…
If it’s a 73mm shell it should only have one 2.5mm spacer (or guide of same thickness) on the DS, and none on NDS.
It was mentioned above that 8120 have a longer axle than the 8100 for a wider chainline using the spacers that come with them.
an 8mm allen key?
Well, yes, one of those, but I already have one of them. XTR M970, and as far as I know, only M970 need special tool TL-FC35 in addition to the Allen key. As far as I know it has no other use.
It really, really annoys me.
I also have six different BB tools, four of which are for Shimano BBs...
8120s run with axle spacers. The Deores will not.
Is the BB on the Whyte fitted with one spacer behind the DS cup and no others?
TL-FC35 was shipped in the box with the M970 cranks. I think I might still have two kicking around in my garage (though only one set of the cranks still in use).
Have re-read, and basically if its as you described, 73mm shell, 2.5mm spacer NDS and BB mounted chain guide DS taking up 5mm that's not a standard setup Shimano wise.
The chain guide is the issue for fitting the Deores. For 73mm shell they need a 2.5 BB spacer and nothing else. The 8120s run axle spacers and sounds like the chainguide is in place of them essentially
Rockthreegozy - yep, there’s a thick chain guide on the DS and a spacer on the NDS - I didn’t fit them! At least your reply confirms there ARE different axle lengths unlike I was told…cheers
What I don’t get is that even if you’re the size of Shimano surely having such a large number of SKUs when you could achieve the same thing with fewer works against their own (and dealers/retailers) profitability
It is deliberate to increase profitability by making you buy new stuff rather than reusing old stuff
I’m not sure that last point is entirely fair TJ. (Specifically shimano chainsets, as opposed to the general case of standards moving on making you buy new stuff).
Sram do different offsets in the chainring, shimano in the crank. Personally, I buy more chainrings than I do cranks so making all the chainrings the same makes more sense to me. Should mean shops don’t have to carry as many different spares etc.
What frustrates me is that I thought we’d got away from all of this when I stopped having to worry about getting the right shell width and spindle length for internal bbs because 9 out of 10 cases with external was just a case of fitting the right number of spacers.
Thanks Scotroutes, but I've bought one now.
The cranks came fitted to a bike I bought so sadly no tool included. I've left it in the toolbox with the umpteen other weird ones I might use once in the next twenty years when someone asks me to fix their bike
swanny - shimano chainrings are not all compatible even non boost 104 bcd ones
It is deliberate to increase profitability by making you buy new stuff rather than reusing old stuff
They were not really doing that with the crank axle lengths, they were trying to keep up with the rapidly evolving frame design of the time.
Their chainring compatibility did take the piss a bit though, yeah.
Some of you need get one of these magnificent bits of colourful aluminium shipped from China.
Chinese anodised Shimano DM chainring tools are also a smart buy, FWIW.
Some of you need get one of these magnificent bits of colourful aluminium shipped from China
Someone got me one of those for Christmas. Looking forward to trying it, but might be a bit wasted on me as all 4 of my bikes have the same MT800 bottom brackets
It is deliberate to increase profitability by making you buy new stuff rather than reusing old stuff
"Component manufacturer makes components" is hardly the profit gouging headline that perhaps you think it is. Plus also, 1. you'd be the first to complain if the likes of Shimano decided to force all bike manufacturers to use their 'standard' 2. at what point in the the past 120 years (or so) of bicycle development would you have preferred everyone stopped innovating? 3. Shimano mostly just reacts to what frame/bicycle manufacturers decide the size will be of various bit anyway, 4. doesn't the wide spread of Shimano components just mean that they can fit the same product range to as many bikes as it's possible? and 5. what's wrong with increasing profitability anyway?
look at the gap from teh crank arm to teh chainstay. they should be the same - alter the BB spacers to suit.
fairly sure i had to remove the (normally required) bb spacer from my deore crank bb to make them fit one of my bikes. i cant really remember which bike but i remember being annoyed/confused it didnt fit! actually thinking about it i think i swapped the cranks with those on a different bike.
It is deliberate to increase profitability by making you buy new stuff rather than reusing old stuff
It's not that - it would be better for THEM long term to only have one 12s XT shifter pod rather than two different ones depending on how you are mounting it. Likewise my new EP801 motor uses a different direct mount tool to mount he chainring to the one the EP8 used. Now the new one uses the same as the XT direct mount tool which I already had but WTF didn't the older motor use that same tool.
I'm guessing their design argument would be 'no performance compromise' so if you can safe a few g, or make something stronger, by designing yet another custom sized locking they'll do it, whereas most other manufacturers try to keep custom tools to a minimum. I can't remember what I came across recently that had reused the isis bottom bracket tool standard to mount something completely different. Wahey, I've got one of those tools from years ago.
I'm pretty sure some of these shimano lockrings are only a few mm diffent in size. are there even two that are the same but with a different number of teeth?
(actually not just shimano - had to remove a SRAM DUB BB recently and found that it needed a unique tool)
It is deliberate to increase profitability by making you buy new stuff rather than reusing old stuff
SRAM, absolutely. Shimano? Less so,
Their MO seems to be to produce the same parts for their 4 year cycle come what may. My guess is there was a lot of eye rolling at Shimano HQ when some other company announced yet another BB standard and they had to fit a longer axle to accommodate it until the next model cycle came round and they could update the crank forging itself.
And the continued existence of 24mm spindled BSA bottom brackets on anything other than BSO's seems to be down to them, otherwise we'd all* be creaking round on press-fit SRAM Dub-STEp-53.5 V2.1 by now.
*well apart form the unluckily adopters of Dub-STEp-53.5 V1.8 (aka universal bottom bracket / UBB ) who now find that their frames are obsolete as the Bluetooth bearing protocol was changed at the same time meaning there are now no longer any compatible as their frame won't take a mechanical bearing but lacks the new mounting standard
SRAM, after initially pleasing everyone by making road and MTB group sets compatible, seem intent on making everything as confusing as possible to prevent any such common-sense ever happening again.
1. you’d be the first to complain if the likes of Shimano decided to force all bike manufacturers to use their ‘standard’
15mm axles
2. at what point in the the past 120 years (or so) of bicycle development would you have preferred everyone stopped innovating?
True, but some of that innovation was unnecessary.
Shimano stuck with 24mm axles and threaded BB's with external bearings. They were still lighter and stiffer than almost all the competition, and had zero compatibility issues (and T47 does a better job of sorting out the frame design limitations). I'm sure Shimano could have made a lighter 30mm crank (or 29mm, looking at you again SRAM) but they didn't because their profits are in selling standard parts that fit as many standard frames as possible.
There are some huge innovations that are worth re-defining standards over, like disk brakes, through axles, or tapered headtubes.
There are some where it really didn't matter like Trunion / metric shocks because hardly anyone ever changed shocks anyway, and even fewer would have transferred them to a new frame.,
And then there's SRAM who will happily make their group-set single figures grams lighter than the last version, completely incompatible with your old kit, and somehow despite the seemingly frantic issuing of new models with new standards, still worse than the Shimano equivalent which will probably fit that 120year old frame.