Iride01 

Sora is a nine speed crank and Tiagra is a ten speed crank. There isn't a set timeline for things to trickle down. All sort of manufacturing and marketing issues along with the timing of the whims of us as consumers. Though not as individuals, but when lumped into a whole for the various trends and fads we pick up on.

Tiagra 4700 is a very old in the tooth product. Just because it, Sora, 105, Ultegra and DuraAce have the same look to them does not mean that they have the same technology and materials going into them.

Whether you are a Shimano, SRAM, Campagnolo user, it's much the same a Ford, GM, Nissan and Toyota. They make high end and low end products. Which do you want on your bike? There are pro's and con's for all of them.

shelbyfv

Excellent advice and should be appended to all threads of this nature.

am8117

1) I can afford Dura-Ace, but sometimes you look for something closer to the speeds of the groupset currently on the bike, i.e. 10 or 9-speed for crank.

2) I want to know if newer is better because I want the better of the two (for any particular lineup). I looked for advice if newer chainrings from the same manufacturer are better not only for Dura-Ace, but also e.g. Sora or Claris.

2a) I do not want what has been reported to break, as in production method-wise.

2b) Any advice on how to identify 2 and 2a welcome because manufacturer does not publish those data.

am8117

I went to check to the best of my abilities:

1) Tiagra 4700 was released 2015:

https://www.rideshimano.com/global/e...rfect-partner/

2) Tiagra 4700 got new subcompact cranks as late as 2019:

https://www.cyclingweekly.com/news/p...options-422507

3) Sora R3000 launched 2016, it's only compact 50/34 as of now still (and triple):

https://road.cc/content/tech-news/18...ru-axle-wheels

4) The non-lineup R460 10sp. subcompacts appeared as early as 2015 (hard to find launch article but can be inferred from the first appearance in lineup charts):

https://productinfo.shimano.com/down...rt_v024_en.pdf

In conclusion whatever trickled down from 4-arm to 10sp was in 2015 and to 9sp in 2016. NB The 4-arm Ultegra (6800) was introduced 2014 as did 105 (5800).

They are all the "very old" by that standard, aren't they?

Germany_chris

Why is this conversation limited to Shimano only?

am8117

It doesn't have to be, but Shimano supposedly moved on to the 4-arm stiffer (as in chainrings not cranks, at least not for the purpose of my original thread) and the way it was trickling down it seems there's no tests anywhere available if it's not just old fashioned stamped aluminium, same alloy, less material, plastic cover, which would actually make it inferior, however cheaper to manufacture.

I am not familiar with the others that well, especially lots of them are either good old fashioned 5 bolts (and very competitive in quality) or direct mount. SRAM still retains the 5 bolts for instance, but I did not want to start whole separate discussion for non-comparable products. Some (i.e. me) do not want to have the GXP bottom bracket and that makes those cranksets not comparable with Shimanos - which makes all kinds of cups for the HTII bottom bracket usable by all cranksets.

am8117

At least now only found (sorry if everyone but me is aware but haven't seen anyone mention this explicitly):

https://bike.shimano.com/en-EU/techn...llowglide.html

As for road, only DA and Ultegra have hollow big rings as of today. So even the 105s and below are supposedly stamped out the same way like the 5-arm design had them, only with one fewer arm to spread the load.

holytrousers

Four arm spiders look so cranky that i wonder why would anyone want to come up with such a design...

Iride01 

Well now, that's a valid reason.

Personal preference is a big factor and if you don't like the looks of something I don't see why you should be made to use it if other things address your sense of aesthetics and performance requirements that matter to you.

Iride01 

I have no idea what your point is. Yes the 4700 group is an old in the tooth group to me. DuraAce, Ultegra and 105 have had several series changes since 2015 and many version changes within each series. Each one of those design changes not necessarily changing the outward look of the products.

Likely design changes to address issue found in earlier versions of their particular series. Whether those design changes are for deficiencies in the previous version or simply changes to improve cost of manufacturing I'd have no idea. You can look within each series and sometimes see that a entire component or part of it was changed. Then the version number for that part changes though it remains in the series. IE. Shimano 5800 started out with a front DR, FD-5800 then just before the series changed, they came out with another version of the front DR keeping it in the same series of 5800. It was the FD-5801. Why, I can only suppose. However it is the same basic design that flowed down from DuraAce and Ultegra.

We have gotten way off from your original question. So if you actually want to spar on this current stuff that seems to fascinate you, then you need to state what it is you are arguing.

As I said, I have no idea what your point is from any of the supposed arguments you think you have made. They don't mean anything.

shelbyfv

Yep.

holytrousers

I would agree with you if it came down to a personal preference, but in this case i was referring to that beauty that comes with the "just right" solution to an engineering problem: when you contemplate an arch or a vault, tree's fractal branchings..
In this case something feels not right about how the spiders look, a single crank arm doesn't seem to fit the spider arms, the forces applied don't look "right"...

base2 

What doesn't look "right" to me is FC-7900 cranks. They are just ugly. I have one I pulled out of a trashcan at a bike shop that I just can't bring myself to molest a perfectly good bike with.

What is right to my eye though is the assymetrical 4 arm design. The crankset only needs to be stiff/strong during the power portion of the pedal stroke. Even then this is proportional to the amount of cross-chaining. The big wide gap in the "X" is material removed where it performed no function. This allows additional material & strength at the narrow gap of the "X" to hold the ring stiffer when needed.

The Shimano assymetric design is doing what the 5 bolt, one hidden behind the crank arm is trying to do.

Maybe my engineering eye is different.
Beauty:
polished crankset by Richard Mozzarella, on Flickr

am8117

Is this based on some forces applicable analysis that can be looked at? Because the arm removed "where it performed no function" would have been the portion of an arm where the mechanical advantage is the largest. If you are however referring to the fact that the chain "bites" at the top teeth and majority of torque is transferred through the forces there, then if the chainring alone is so stiff, why are two arms needed at the bottom, why not only one?

Aesthetically however, I agree about the 7900, I wonder how we look at 4-arm cranksets in 5 years though.

am8117

I was only reacting to the dismissive notion that 4700 are somehow very old and thus non-relevant when in fact it's the same 4-arm design (trickled down). The 4-arms whether with hollow big rings or not, glued or forged, are still 4-arms - that part of physics is non-disputable.

My tentative argument, if you will, has been that the way 4-arm trickled down it just removed lots of material, but did not much to add stiffness. For the lower models it's just for the looks provided by (arguably non-aesthetically pleasing) plastic with shoddy ramps.

I'd like to believe I was in fact trying to get back to the original question if anyone has any extra input on the 4 vs 5 arm design as such, no matter which lineup.

But I appreciate all the inputs provided so far in any case.

Germany_chris

Here's a SRAM crank on a Shimano standard bottom bracket.


Here's a Rivendell (Andel) crank on a Shimano standard bottom bracket

There is zero reason to use a Shimano crank because you want to use a Shimano bottom bracket. Once you stray from Shimano you're going to find a plethora of chainring choices.


I get that you're probably not interested in going back in time standards wise here's a modern very expensive crank that has a narrow Q and is lighter than most modern cranks including BB. This crank is so good that I'm considering spending another ~$600 to buy replace a mediocre w/expensive BB on the commuter.

The larger point isn't my choices (though I'm proud of them) are the best (I mean I have a ~$100 crank running on a ~$250 BB) it's that there is no reason to stick to Shimano, the second you leave you choices of chain rings and their quality improve greatly, for example that silly old school square taper crank has a 104 bcd spider with 44/36 chain rings you're not going to find that on anything else.

Iride01 

Well to get back to the original question my input would be that as long as I've been riding, people have been bending their chainrings. Doesn't matter how many spokes they have. Some might have been from being inadequately designed to handle the stresses, but in the cases I can find on the internet, many of them seem to simply be a person shifting gears at a time when they are also producing massive amounts of torque, and assumedly at a very slow cadence.






So I don't know what to tell you. The four arm doesn't seem any more prone to or less prone to bending to me as people have be asking why they bent their rings at least since I began riding bikes in the 1960's, and I'm sure before that.

In the grand scheme of things, it probably isn't something that is going to happen to you. Unless you shift when putting out massive power and at low rpm. I have never bent a ring and I use to be that person that put out a lot of power at low rpm. I just had sense enough not to shift gears at that moment or to slack up a tad on the power.

I have both Ultegra R8000 cranks and 105 5800 cranks and there are differences in the chainrings themselves. The 105 rings are heavier. The Ultegra rings make a different sound when I shift than the 105 rings. The rings though are interchangeable from one spider to the other. If it wasn't for the fact the sculpting of the arms is slightly different, then you'd never know.

Never has bending a chain ring been a concern to me. If it happens it happens. I suppose once in my life I would actually replacing one for failing instead of just for simply wanting a different crank. Few have I ever even worn out before replacing them.

base2 

Because when the drive side arm rotates 180 degrees, the non-drive side crank arm has a foot on a pedal generating a similar amount of power that is then transferred through the spindle into the attached chain ring.

am8117

Yes of course, I just thought the spindle already keeps any potential twisting movement in check, so there's no need to keep the chainring "stiff" in that half of stroke.

am8117

So first of all that's a really beautiful bike!

I am getting a bit lost with the bottom brackets here, I searched for the SRAM crank and that's Rival 22 I believe:
https://www.sram.com/en/sram/models/fc-riv-2x11-a1

But that is GXP "spindle interface" still, is it not? When I meant BB compatibility I was getting at 24/24mm each side, not the BSA socket. I understand I can buy other BBs that fit into multiple sockets, but the availability / interchangeability of parts plays a big role for me (and for fair comparison).

Before I steer the thread away from my original caption, the Rival 22 is also "older" 5-arm, Shimano had 5-arm at the time too. The currect SRAM Rival is going down the same route with 4-arms, plastic stuff etc (https://www.sram.com/en/sram/models/fc-riv-d1) and they abandoned their own GXP to introduce yet another BB.

About square taper, again not to veer off too much, I just hate the idea of having to have crankarm puller again. I just really liked the HTII BB standard and 24mm each side 2-piece cranksets ... until they (all) started doing 4-arm for the recent stuff.

PS Is that a leather handle to grab the bike above the BB?

am8117

Do you mind providing links for those? I cannot google find the Rivendell one and I can't identify the other one from the looks either.

am8117

They look like really cheap chainrings though, something that lower end Shimano's now might be after they covered the rest with the plastic. With the previous generation when the look of actual chainring was exposed, this would have been easier to see.

I do not shift under load, but outring bending it was not a concern.

What I was getting at in the OP was the stiffness of those plastic-concealed chainrings, in practicality how much would I end having FD chainrub possibly due to the 4-arm crankset chainring flexing, especially on the lower end models (and in comparison with the same but 5-arm generation).

am8117

I wouldn't have noticed but the 4-arm design has now trickled down all the way, so there indeed is a crankset that has 4 bolts and virtually no plastic cover - must be a weight saving measure.

The technology behind looks indeed high tech.

https://bike.shimano.com/en-EU/produ...o/FC-T551.html

Iride01 

Weight is a big factor for high end stuff. Longevity, not so much. Bike parts don't need to last forever.

shelbyfv

Iride01, it's a waste of time. Seems something isn't "right" here, even beyond the attention seeking. Time for the iggy list.