Freewheeling Design for the Shimano Hollowtec II Crankset

[ScooterMan101]

How would you design a freewheeling crankset , using the already off the shelf Shimano Hollowtec II 2 piece Crankset ?

Shimano Hollowtec II 2 piece cranksets have spiders on the drive side crank arm , they range from 64 BCD / 104 BCD to 130 BCD.

I think it possible to use a 3 chinring Shimano Hollowtec II Crankset, take off the three chainrings and make a freewheel with bolt holes to use two chainrings , one on each side of the freewheel , one to the motor , and one going back to the cassette.

What Idea do you have for this ?

Who here on E.S. can make this and sell to those of us who already have Shimano Hollowtec II cranksets on our bikes ?

 

[Drum]

I agree that it would be a very useful "bolt on" adaption if possible.
The Hollowtech (and similar cranksets from other manufacturers e.g.Raceface) are so much stronger than the ISIS / Octalink that they are the only real choice for heavy offroad use.
Will do some thinking.. and some research on available freewheels.

 

[simon.s]

I agree that it would be a very useful "bolt on" adaption if possible.
The Hollowtech (and similar cranksets from other manufacturers e.g.Raceface) are so much stronger than the ISIS / Octalink that they are the only real choice for heavy offroad use.
Will do some thinking.. and some research on available freewheels.

Stiffer, yes. Stronger, arguably, they're certainly harder to bend. See "stiffer". They have a much shorter life, even with only a human pushing on them. Bearings go out fast, you're lucky to get 2K km with only human input, I'd expect a lot less with motor drive as well.

People pan square taper, but the only reason I changed the 20 year old square taper BB (BB-UN-72) in my Sunn was that I needed to remove it to repaint the frame, and it was horribly corroded into the bottom bracket; removal was destructive. My 15 year old road bike BB, also square taper, owned from new and no idea what it is, has at least 30K km on it (it's on its third set of chainrings, though). I've never had a hollowtech crankset run a set of bearings for more than a season. Speaking of which, need to do the kid's, which have failed with about 500km on them. It's antime / dirt ingress thing, I think.

 

[ScooterMan101]

@ Simon,

The outer bearings that the Shimano Hollowtec II ( and the even newer Direct Drive Cranks use )
are
Outside the BB shell, I forgot the advantage at this time, it is there otherwise only one or a couple of company's would be doing it. The Fact is that many
most companies are , Not , using the older and heavier BB's , they are now using outer bearing's.
Also
When I spin a Square Tapered BB , I feel much more resistance than when I spin the crank of a Hollowtec II crankset in their Outer Shell Bearings. ( BB30's are even smoother , and more efficient )
And
Outer Bearings from Shimano are cheep, just as cheep as the , Much , heavier square tapered BB's .
Add to that that when you have a motor, you will have the drive sprocket/chainring having more torque than human leg's
So
You want the Outer Bearings that Hollowtec II's and the Direct Drive Cranks use, because the angle of torque is less than on the older Square Tapper BB's .

 

[simon.s]

I forgot the advantage at this time, it is there otherwise only one or a couple of company's would be doing it.

The bicycle industry is extremely good at producing solutions to non existent problems, especially when it means you have to pay extra for the privilege. Put it this way. Selling a bottom bracket to an OEM (at OEM prices) that will in 99% of cases last the lifetime of the bike is less lucrative than selling the owner of a bike a set of bearings (at retail price) every year or two. The [strike]argument[/strike]excuse was stiffness and weight.

Let's take an example. Tange make bottom brackets, they're equivalent in spec to a top of the range and now unobtanium BB-UN-91. Lighter, too. You can buy these, retail, for around 20 GBP. Or, more to the point, around the price of a cheap set of bearings for an outboard BB.

Stiffness wise, I can't say I see much of a difference. I do ~2500km offroad and around the same on road, I'm at 25km+ of ascension this summer. 90% of that has been on square taper, although I did borrow the boy's (mountain) bike for a while while my forks were on the bench - he's running outboard bearings and I didn't notice *any* difference at the crank on a couple of 50km+, 1000m+ vertical rides. I ride a lot, but I'm not a professional cross country racer either. Maybe 0.001% of users would notice a difference, but they change their bottom brackets every race anyway, and I can guarantee their brackets don't cost 20 quid.

Weight wise, I've got the Tange BB at 230g, XT "hollowtech" (which refers to the cranks themselves being hollow) cranks at around 630g including rings. An equivalent triple setup with outboard bearings : FC-M770, including bottom bracket, around 860g. I'll call that a draw.

The bearings in the Tange BB are stock ABEC bearings, 7002 IIRC. Dynamic load rating around the 6500N mark. Hollowtech II bearings are 6805, Dynamic load rating - 4500N. There is, I'll admit, a slight mechanical advantage in terms of the load those bearings will take, and in any case you'd be hard pushed to put half a tonne on your crank without it snapping clean off - again, I'll call it a draw, but I'll note that ABEC trumps deep cup in this usage (enduro sell ABEC bearings for hollowtech II, they are a worthwhile upgrade if you can't get them off the shelf from your local bearing supplier)

All that leaves is longevity, which is a hands down win for the sealed cartridge square taper or octalink BB. If you want maintainability, go all the way to an open cup design which wins on every front except having to do maintenance on it, especially offroad.

See also steerer tubes. Do you know what diameter a CBR900 steerer is?

Snake oil. It's pretty much all snake oil, designed to make you pay more, and more often.

 

[liveforphysics]

Wouldn't the bottom bracket spindle bearings only turn while you pedal if the sprocket is on a freewheel?

 

[simon.s]

Back to the original question, it's gonna be relatively hard to do, and it's liable to pull your right hand crank well outboard.

Option 1 would be to make up a new spindle (or modify the existing spindle) that mounts just the spider, and run a separate shaft down the inside for the cranks, coupling the two with a freewheel or one way bearing arrangement. That's gonna be heavy (not that we care for electric usage) and complex (notably, it's gonna be hard to arrange for tensioning the spindle with the spider on it).

Option 2 is to mount the spider itself on a freewheel, and leave the pedals on the "original" spindle. That's a far more sensible setup, but it only leaves you 15-20mm or so of width to fit your freewheel into. You might be able to modify an existing spider, but my gut feel is you'd have to make your own. Plus, you know, butcher the drive side of your expensive crankset

Do-able, but far from easy.

 

[ScooterMan101]

Not having a freewheeling crankset, and not ever seeing one, I am still trying to figure them out.

As for your question, I thought the reason for a freewheel on the crankset with a mid-drive , is to allow you/us to not pedal but let the motor still work running power back to the rear cassette through the chain ?
So
The objective is to just design it to work with the 2 piece ( in this case the Shimano Hollowtec II crankset ) instead of the square tapered 3 piece design.
Luna makes a freewheel with 4 holes on it , I think 64 bcd. so have / make a piece that attatches to that but does not engage the crank arm.
Don't know how to do it myself, so the reason for world wide crowd thinking here.

Wouldn't the bottom bracket spindle bearings only turn while you pedal if the sprocket is on a freewheel?

 

[ScooterMan101]

# 2 option is what I have been thinking about all along. Not much room , but if enough for the freewheel and two chainrings then doable .

And BTW , I have found all the improvements that the Bicycle Industry has come up with, very good ! , as a consumer I am very happy with such improvements in the better efficiency of BB 30 bearings, and to a lesser amount the Outer Bearings that Shimano came up with , and now the Direct Mount Systems.

And I like the feel of a frame with a tapered head tube 1.25 inch top and 1.5 inch bottom. Especially when I am going down hill .

And the stiffness and better control of the newer bigger stanction tube suspension forks,

And the way I can now take off wheels on my bike with Through Axles, and put them back on and still have the same alignment on Brakes so I don't have to adjust them,

And the better ride qualities of newer frames

And Better Tires

And , other items that are improvements over the bikes I had owned in the past.

Improvement is GOOD ! , lets embrace it , and be Happy.


Now lets keep this thread and posts on the positive side, there is a solution for using the cranks and outboard bearings that many / most bikes are now being equipped with .

Back to the original question, it's gonna be relatively hard to do, and it's liable to pull your right hand crank well outboard.

Option 1 would be to make up a new spindle (or modify the existing spindle) that mounts just the spider, and run a separate shaft down the inside for the cranks, coupling the two with a freewheel or one way bearing arrangement. That's gonna be heavy (not that we care for electric usage) and complex (notably, it's gonna be hard to arrange for tensioning the spindle with the spider on it).

Option 2 is to mount the spider itself on a freewheel, and leave the pedals on the "original" spindle. That's a far more sensible setup, but it only leaves you 15-20mm or so of width to fit your freewheel into. You might be able to modify an existing spider, but my gut feel is you'd have to make your own. Plus, you know, butcher the drive side of your expensive crankset

Do-able, but far from easy.

 

[simon.s]

# 2 option is what I have been thinking about all along. Not much room , but if enough for the freewheel and two chainrings then doable .

And BTW , I have found all the improvements that the Bicycle Industry has come up with, very good !

This veers wildly offtopic, and I'll shut up after this but...

Yes, there have been major improvements in bike technology over the years. But there's been a lot of change for the sake of change. There's only so many ways you can innovate around a bike, after all. Here's some inspired by your post, and some off the top of my head.

If someone is telling you that the Hollowtech style BB is stiffer, yeah, I'll buy that. I don't think it's meaningfully stiffer for any significant proportion of the riding population, but yeah, stiffness increases per square of diameter, and the mounting system for the cranks is definitely better - taper mounting works great for axial loads, not so great for diametric, that's why the bolts at the end are there. However, "more efficient"? Industry bullshit fed to you by someone who wants to sell you 30+ dollar bearing sets (that the majority of people have to pay over the odds to get them badly fitted by a trainee till monkey at halfrauds).

Oversized headsets? Not so certain. Never bent a head tube yet, even in downhill with 1" head tube (although the hits weren't so big BITD). Bent plenty of frames, forks, bars and wheels over the years, even a seatpost, but never a head tube. Threadless headsets, though? Yeah, mahoosive improvement, as long as you know how to check and adjust for play. Most people don't know how to adjust for play.

Suspension? Yeah, today's (higher end) suspension is out of this world. Stock OEM stuff, not so much, but it's still ahead of the old stock OEM stuff. Elastomers. <brrrrr>

Never had to adjust my brakes after dropping the wheels out from a QR, and nor has anyone I've ever known. I call "you swallowed the industry bullshit" on that one. There are some arguable benefits to through axles, but "brake adjustment" isn't one of them IME.

Ride qualities of newer frames? Close to 100% down to suspension. Ride a rigid carbon bike against a top end rigid steel bike from the tail end of the '90s, there's bugger all in it apart from weight. Aluminium frames need suspension or you lose your fillings. Just MHO, of course, as "feel" is totally subjective. On the other hand, modern frames are *much* stronger, regulations require that.

Frame materials. Aluminium work hardens and cracks or snaps. You know why you don't see many people riding 20 year old aluminium frames? Composite frames eventually shatter or snap. I had an ALAN alu / carbon frame, that was *definitely* the best of both worlds - when I say I had one, I had 3, replaced twice under warranty. Titanium? Cracks. Steel - bends back, within reason. Dunno how good the recent stainless framesets are.

Tyres, yeah, they're loads better.

You missed the big one. Hydraulic disk brakes. Man, they're good. Even the *shit* ones are good compared to cable disks, v-brakes, or cantilevers. I've raced DH with cantilever brakes, my arse still puckers when I think about it. No point pulling the levers, they do next to nothing.

Dropper posts. There's another good one. Yeah, I had a Hite-Rite, ain't no way I'd put one back on a bike that *I* was going to ride.

Clipless pedals. Awesome. Platform DH pedals with pins. Awesome also.

Cassettes and freehubs. Awesome.

Shimano's lightened rear hubs in the XT / XTR series around *mumbledy* M760 or so? Super hyped, not so awesome.

Remember Aero spokes? Remember filing your hubs to make the bastards fit? Remember they were heavier than double-butted spokes? Remember they saved maybe 1W at 50km/h+? They're still around, still super expensive, still no use if you're not a professional rider doing the TdF. But hey, they look cool.

[Edit] Oh, I forgot. You could probably add 1x11 / 1x12 chainsets to the mix. Lighter and simpler, although potentially less long-lived. Rode a friend's 1x11 XC rig the other day, no pissing about. Very "Karate Kid" - "Shift Up, Shift Down"

 

[liveforphysics]

Proline BMX splined spindle bottom bracket is very strong, and smaller diameter shaft for the sake of bearing life not requiring ultra thin-section bearings. I used to break square drive aluminum crank arms every few months of hard riding before going shaimano ultegra (it's a cyclocross bike) splined bottom bracket and cranks and it's been perfect riding though a lot of rain and mud and never washing it.

 

[ScooterMan101]

@ Simon,

When I started this thread I was hoping it would , not , get it sidetracked with different opinions about what is best, and how the Bike Industry keeps coming up with products . Whether you / anyone believes it is a conspiracy by the bike company's to get us to buy new every few years,
Or
You do see the benefits of most all of the newer parts over the past 5 or so years now.

The Fact Remains that those newer parts , Is , what is coming on our new / and even a couple of years old , Bikes .

I did not write about the benefit of Disc Brakes which I now only ride with, and dropper posts , and the other items you listed as an improvement because I had already listed what I thought was enough above to make the point.
( I am glad you have mentioned all those improvements )

I have felt the difference in Tapered Headtubes / Tapered Steerer Forks . It is not that I have bent any non tapered headtube frame or fork , it is just that I feel more secure in the handling when going down hill. and/or any sudden change in direction .

And I like the big spindle and the bearings of the BB30 system. I have built up three different bikes in the last 3 years with all three systems , ( Square Tapered Cartridge BB, Shimano outer bearings for Hollowtec , and BB30 )
And the BB30 is far better , meaning it spins much easier than the others, allot better than old Square Taper Cartridge BB's . And I do know about the benefits of stronger parts when the O.D. is larger, Hangliders that I was flying over 30 years have done that for several decades now . ( Notice the newer system , the Direct Mount Cranks like Race Face Cinch and E+Thirteen DD Cranks have 30 mm spindles )

And through axles I like for a number of reasons , I did not mention about what I like about that and them is the fact that I can have two difference wheel sets, ( one with street tires and one with wide , aggressive knobbies ) and not have to make any adjustments to brakes or derailleur . I have had to adjust the brakes and derailleur when using two different wheels in the past. So even if you have not had to do that , I have . I want to have two wheelsets in the future so am happy with newer although more expensive through axle wheel sets.
BTW.
I have two rear Q100c CST hubs, the same hub, the same 201 rpm version, same disc rotor and same cassette, and when I switch from one wheel to the other on the bike ... I do have to adjust the Brake and Derailleur .


Now What I did not say before, and need to do now is ... I looked up the cost of getting all the parts to make the freewheel crank sets that are being used in / on e-bikes now.
And
One of the biggest reasons I want to have designed/made a freewheel system for Hollowtec II and other more modern cranksets like Direct Mount, is ... That the cost of getting all the parts from places like Sick Bike parts or Stanton, or wherever is ... very expensive !

It is better if we all have the option to buy just the freewheel part that can be put on the Cranksets that we already have. Resulting in , much needed, Cost Savings. And also to not have the stock parts now just sitting in a box in storage. These are the main reasons why the need to design a freewheel that will work with the parts we already have.
^ ^ ^
There I should have focused and written that last paragraph above , instead of saying that the newer crankset's and BB systems are better, ... because each person has their own idea of what is better.
But most everyone can agree that to have a bolt on solution that uses the existing crankset that we already have and are riding with, is cheaper and therefore better .

 

[ScooterMan101]

Thank You for mentioning this, Shimano Hollowtec II with their splined spindle and 24 mm O.D. Spindle have been around for a while now. and As I write this Shimano still has not come up with a 3 piece version, also called Direct Drive by other companies so I am guessing they have a good product there since Shimano is constantly improving products . ( Sram and other companies are doing constant improving as well ).
I am guessing that the short bearing life that Simon is getting from Shimano outer bearing system, is mostly a result of water ingress .
I do however , now that I have taken apart a set, like the Direct Drive Crank system from Race Face better, all you need is two allen keys , one size for one side and another size for the other to take off the crank arms.

Back to a design on how to make the crankset we already have on our newer bikes work with a DIY mid-drive,
Would a small thin clutch work on the crankset ?
or
A combination of Small thin clutch, and around the outer diameter of that a freewheel ? Anyone ?

>

Proline BMX splined spindle bottom bracket is very strong, and smaller diameter shaft for the sake of bearing life not requiring ultra thin-section bearings. I used to break square drive aluminum crank arms every few months of hard riding before going shaimano ultegra (it's a cyclocross bike) splined bottom bracket and cranks and it's been perfect riding though a lot of rain and mud and never washing it.

 

[ScooterMan101]

Just now remembered ... when installing my Shimano Outer Bearing BB set on to the frame a couple of weeks ago,
I first watched a couple of youtube videos , on how to install them .
In one video, by a bike Mechanic , he said ... to Not , over tighten them onto the frame , aka: over torque them .

Perhaps that , along with some water / moisture ingress, is why Simon is getting such short life out of them.

The bike shop he is taking his bike to is over torqueing them on to the frame to tight ?

I did notice when I did over torque them the crank arms/spindle did not spin as smooth.
I had to play around with several adjustments to find that, " just right " amount torque without using a torque wrench.

 

[simon.s]

Yeah, a direct mount approach would be great. But it's not going to happen, at least not for an off the shelf solution, there's too many competing, incompatible "standards" out there. Take a look at this, bearing in mind that's just a compatibility matrix for the major cranksets and bottom brackets, and it doesn't start to cover chainring / spider / crank combinations.

In a sane industry, the major players would get together and agree a standard to go forward with. Pretty much everyone agrees that clamping to a splined shaft is the way to go, so why not adopt a single splined shaft format. Hell, we've already got a pretty good one, the hyperglide freehub spline pattern - it keeps stuff mounted solidly, and in the correct orientation. Scale that down to, say, 24 or 25mm, and you're good to go. Everyone produces stuff that simply slips onto a standards compatible spindle. You want a hope spider with race face cranks, a shimano spindle and SRAM bearings? Go for it. Back in reality, individual manufacturers can't even make their minds up what they want to use internally, and have multiple competing standards between ranges. It's crazy.

As for how to go, you probably want something where the spider / rings mount on a splined shaft, say Race Face "Cinch". Then you need to go look at the various freehub patents. The actual "free" bit of a modern freehub is remarkably thin, but it's still gonna be hard to get it to hang together in the space you have available. There's a pretty good reading of one of Shimano's recent freehub related patents here : https://www.bikerumor.com/2016/01/26/shimano-patent-shows-silent-ring-drive-hub-internals-that-could-be-the-next-dura-ace/

And no, I mount my own stuff. There's a very god reason outboard bearings fail, and it's to do with - well, I'll let you work it out for yourself. My previous post gives a couple of bearing references, you might want to consider both why you shouldn't overtorque, and why it's a big deal if you do.

 

[ScooterMan101]

Edit :

It was the over tightening of the plastic bolt on the non drive side that puts too much pressure on the bearings, creating friction on the bearings thereby making them not spin as good, which would certainly make the bearings wear out faster.

Just now remembered ... when installing my Shimano Outer Bearing BB set on to the frame a couple of weeks ago,
I first watched a couple of youtube videos , on how to install them .
In one video, by a bike Mechanic , he said ... to Not , over tighten them onto the frame , aka: over torque them .

Perhaps that , along with some water / moisture ingress, is why Simon is getting such short life out of them.

The bike shop he is taking his bike to is over torqueing them on to the frame to tight ?

I did notice when I did over torque them the crank arms/spindle did not spin as smooth.
I had to play around with several adjustments to find that, " just right " amount torque without using a torque wrench.

 

[ScooterMan101]

There probably will be a time when the Major players agree on a single standard, or two major standards.

We just happen to be in the middle of that time when it is not yet sorted out.

I have a used Race Face " Cinch " Crankset, and I do think, now that I see it apart , I most certainly would like to see that as the one the industry goes with, or even the FSA version.

The FSA version from what I have read , does not have the dished chainrings that the R.F. Cinch does, FSA has flat chainrings, and to change the chain line in or out , you just add a spacer to one side or the other of the chainring.

FSA and Race Face might just be the ones that will win out in the long term.

I did start another thread the same day as this one , to see how we ( people with more experience with design than me ) can design a freewheel for the Race Face " Cinch " system.
That one I see could be easier because only a new Spindle has to be made, just a little longer , so as to provide enough room for a freewheel and two chainrings.

 

[bh4801]

Shimano Saint Hollowtech freewheeling crankset 170mm arm 2 x 38t 104mm BCD chainrings

 

[bh4801]

18 magnet ring for cadence sensing. It takes a quarter revolution to obtain an averaged reading of cadence plus direction
Likewise, power off is real - time, no delay

 

[bh4801]

Chainline is 51mm. Exactly the same as original.

 

[bh4801]

Stieber CSK35PP sprag clutch with a support bearing
This is STRONG AND STEALTH.
No ENO clicking.

The Stieber CSK35PP is rated at 175 Nm nominal, twice that max.
At 170 mm crank length, the crankset is strong enough for a 100 kg / 220 lbs rider STOMPING on his pedals

 

[bh4801]

Polyurethane V-profile compression seal

 

[amberwolf]

Bh4801, what are you trying to say with your pictures?



(you can attach more than one image per post, as well as typing text into the post to explain the images).

 

[bh4801]

Bh4801, what are you trying to say with your pictures?

A picture speaks a thousand words, or so.
The topic comes up now and then so for your viewing pleasure (hopefully) I posted images of my Shimano Hollowtech Saint freewheeling crankset.

 

[amberwolf]

Thank you for updating your posts with info that explains the pictures.

Is this a crankset you made yourself? Or purchased somewhere else?