Freewheel strength

[matt slegg]

Something Ive pondered for a long time, are hube freewheels considered stronger than front screw on or splined freewheels?

Do number of engagement points equal more strength?

Who makes the strongest front screw on or splined freewheel?

[La Bourde]

I won't say so.

A screw on or splined freewheel has a bigger diameter (the inner diameter ist bigger than 35mm). Thus the part designer has more freedom in his design. The surface in contact could be higher too. On the other side, having a bigger steel part means much more weight (and having more surface in contact can lead to more drag - but this is negligible).

Another advantage to have a bigger diameter is that the relative backlash (play) is smaller. Using the same machining precision, the bigger the pawls, the smaller the undesired tilt of the pawl will be.(better engagement, may skip less)

A second problem with a freehub is the hub axle itself. You will have a huge load on it and on the freehub bearings and here again the small amount of space available makes things harder to design.

So it seems that having a front screw on or splined freewheel is better. But steel is not cheap (and you have to use steel or titanium due to the forces) and machining a large steel surface even less.

So the build quality of a front freewheel is often not that good compared to the one of a freehub (which is per definition an expensive part).

 

I think too, when embedding the freewheel mecanism in the hubshell, one can use its own strength.

 

To me, the current design of hubs (including those with 12mm axle) could be improved for trial riding.

This is not possible for other mountain bike discplines because one wants a wide gear range and a small chainring. This implies that a small sprocket is required (10t or 11t with current chain standard. Having less teeth will lead to the "polygon effect").

 

I think having both implementations available on the market means that none has a big drawback.

 

Edited January 14, 2021 by La Bourde

[Mark W]

14 hours ago, matt slegg said:

Something Ive pondered for a long time, are hube freewheels considered stronger than front screw on or splined freewheels?

Do number of engagement points equal more strength?

Who makes the strongest front screw on or splined freewheel?

Just to clarify a few things - when you're saying "hub freewheels", are you referring to a freehub like a Hope, or using a freewheel on a fixed rear hub? If you mean a freehub, they will generally be a little stronger. The biggest weak point of a freewheel is the outer shell, something which isn't the case with a freehub. The constraints on design for a freewheel mean that they can only make that outer shell a certain size and thickness, whereas for the ratchet built into a hub there isn't the same issue.

If you're talking about a freewheel on a fixed hub, the freewheels themselves are the same as those used up front so there's no real difference in that sense. The splined vs. screw-on thing doesn't make much difference. All that will really change is a company will spec either a splined or a screw-on fitment for it. The rest of freewheel core doesn't fundamentally change. Your choice of splined or screw-on will be dictated more by the cranks you get - if you have screw-on cranks, you'll need a screw-on freewheel. If you've got Echo splined cranks, you'll need an Echo splined freewheel. If you've got something like the Clean or Crewkerz splined cranks, you'll need one of their HG-spline type splined freewheels. If you've got the Trialtech Sport Lite Splined cranks, you'll need the Trialtech Splined freewheel.

For engagement points, theoretically the more you have the weaker the design will tend to be as you'll have to have a progressively finer toothed ratchet, but as far as most freewheels on the market got they're all quite close to each other so there isn't a huge change there. There are some shit freehubs out there with higher engagement points where the compromises the companies have made to get that increased number of engagement points have reduced reliability, but there are still strong, high engagement point hubs out there.

In terms of strength of freewheels, the 135-click freewheels you see on the market now (e.g. Jitsie, Comas) are all the same. The 108-click freewheels are all going to be basically the same model too. Things are a lot better as far as freewheels go now than they used to be 5-10 years ago, so choosing one is safer in that sense. They used to be much more hit and miss, whereas now, to be fair, they tend to be much more reliable. You'll still get stories of people breaking any of the ones that are out there, but that's inevitable with any part. If it was me and I had the budget, I'd go for one of the sealed bearing 135-click freewheels as they seem to be holding up well for people, and you get a bit more outer shell stability which should help long term.

[matt slegg]

Thank You. Sorry should have been more clear. When I say hub freewheels I mean like Hope or Chris king.

[La Bourde]

7 hours ago, Mark W said:

In terms of strength of freewheels, the 135-click freewheels you see on the market now (e.g. Jitsie, Comas) are all the same. The 108-click freewheels are all going to be basically the same model too. Things are a lot better as far as freewheels go now than they used to be 5-10 years ago, so choosing one is safer in that sense. They used to be much more hit and miss, whereas now, to be fair, they tend to be much more reliable. You'll still get stories of people breaking any of the ones that are out there, but that's inevitable with any part. If it was me and I had the budget, I'd go for one of the sealed bearing 135-click freewheels as they seem to be holding up well for people, and you get a bit more outer shell stability which should help long term.

One thing I did not appreciate with the 135-click freewheel I bought, was that there was a HUGE drag! Does it get better after "breaking in"? I sent it back.

7 hours ago, Mark W said:

The constraints on design for a freewheel mean that they can only make that outer shell a certain size and thickness, whereas for the ratchet built into a hub there isn't the same issue.

What kind of constraints? To me it the opposite. You can't increase the size of the outer shell of the freehub to a certain limit (wheel geomerty) and the size of the axle is fix.

[AndyT]

Who else remembers the fun of the ACS claw, 16? 18? 24? point engagements I can’t remember. They would break all the time, what a nightmare to remove them... good times !

 

Todays freewheels are insane, different world. 

Edited January 14, 2021 by AndyT

[cwtrials]

18 hours ago, AndyT said:

Who else remembers the fun of the ACS claw, 16? 18? 24? point engagements I can’t remember. They would break all the time, what a nightmare to remove them... good times !

 

Todays freewheels are insane, different world. 

I hated those freewheels.

When I first got into trials I couldn't afford a chris king hub and front freewheel wasn't really accessible.  I used to buy shimano deore hubs for like $12 each online, and break one every month or so.  The axles tended to break.  Learned to build wheels fast.  The old freehubs has problems with the axles, but newer ones are pretty beefed up.

 

That being said.  I think a quality freehub like a Hope or I9 and also decent freewheels are going to be pretty dependable, so breaking one for most people is either going to be hypothetical or one of the those weird rare things.  Freewheels are a bit more cost effective.  I'm 230 lbs and ride like a sack of bricks and can't remember the last time I broke a freewheel or freehub.

[AndyT]

On 1/15/2021 at 1:13 PM, cwtrials said:

I hated those freewheels.

When I first got into trials I couldn't afford a chris king hub and front freewheel wasn't really accessible.  I used to buy shimano deore hubs for like $12 each online, and break one every month or so.  The axles tended to break.  Learned to build wheels fast.  The old freehubs has problems with the axles, but newer ones are pretty beefed up.

 

That being said.  I think a quality freehub like a Hope or I9 and also decent freewheels are going to be pretty dependable, so breaking one for most people is either going to be hypothetical or one of the those weird rare things.  Freewheels are a bit more cost effective.  I'm 230 lbs and ride like a sack of bricks and can't remember the last time I broke a freewheel or freehub.

i rocked the silent clutch shimano rear hub on a koxx cheat code... REALLY weird hub ! like always engaged, no latency - instant pedal everywhere. NOT strong .

 

I currently ride a 21 yo king on my hex, a v old hope 2 on my *** and a 135fw on pogo.

 

King still fav... 

[La Bourde]

I had also some ACS back in the days on my Koxx Cheatcode! Always getting loose, noisy, skipping ... hell on earth.

Yesterday I rode with a young guy, I never met before. He was riding DJ before. I was surprised how fast he learned some street/trials moves. Then I realized how easier it should be now: the geometries are dialed, the bike parts are strong enough and easier to get,  there is tons of videos and a lot of tutorials on YT ... and the freewheel/freehub are safe

[monkeyseemonkeydo]

I used to ride around with a nail in my pocket so I could use it to tighten the lockring. Brace the nail against the chainstay, insert in the pin spanner hollow and roll the bike backwards. Ah, those were the days...!

[ben_travis]

30 minutes ago, monkeyseemonkeydo said:

I used to ride around with a nail in my pocket so I could use it to tighten the lockring. Brace the nail against the chainstay, insert in the pin spanner hollow and roll the bike backwards. Ah, those were the days...!

 Ingenuity at its finest

 

[Mark W]

On 14/01/2021 at 6:30 PM, La Bourde said:

What kind of constraints? To me it the opposite. You can't increase the size of the outer shell of the freehub to a certain limit (wheel geomerty) and the size of the axle is fix.

You could increase it by a meaningful amount without affecting the strength of performance of the wheel as a whole. In some ways, the shorter spokes you'd need to increase the ratchet size would be beneficial. You've also got more width for the ratchet area you can play with to dissipate the load, and also more options for what you do with it. The axle size isn't fixed either, especially. Even within their own designs, Hope have altered the outer diameter of the Pro 2 Evo axle from 15mm to 17mm for the Pro 4. By contrast, there's basically nothing freewheel manufacturers can do, especially as a lot of them are based around a platform that allows the option to drop down to a 16t outer shell (there isn't really any trials freewheel on the market that is specifically designed to be 18t only, and to use all the available space). The inner diameter of the freewheel is fixed, and the outer is too, so there isn't any room for change. With a freehub, you have a lot more flexibility.

High engagement freewheels will generally 'suffer' from having more drag. A lot of it is just down to the strength of the springs, the number of pawls and the ratchets themselves. Front freewheel systems are inherently more draggy too. There's not really any way around it unfortunately.

[La Bourde]

18 minutes ago, Mark W said:

You could increase it by a meaningful amount without affecting the strength of performance of the wheel as a whole. In some ways, the shorter spokes you'd need to increase the ratchet size would be beneficial. You've also got more width for the ratchet area you can play with to dissipate the load, and also more options for what you do with it. The axle size isn't fixed either, especially. Even within their own designs, Hope have altered the outer diameter of the Pro 2 Evo axle from 15mm to 17mm for the Pro 4. By contrast, there's basically nothing freewheel manufacturers can do, especially as a lot of them are based around a platform that allows the option to drop down to a 16t outer shell (there isn't really any trials freewheel on the market that is specifically designed to be 18t only, and to use all the available space). The inner diameter of the freewheel is fixed, and the outer is too, so there isn't any room for change. With a freehub, you have a lot more flexibility.

High engagement freewheels will generally 'suffer' from having more drag. A lot of it is just down to the strength of the springs, the number of pawls and the ratchets themselves. Front freewheel systems are inherently more draggy too. There's not really any way around it unfortunately.

Thanks for the answer.

As far as I know, there is two standards for screw-on freewheel: M35 (the most common) and M30 (still used on some cheap BMX, allow to have a 13T outer shell).

Using a Shimano 24mm steel axle (best design by the way), it will let you 3mm on each side to fix the freewheel. And then you have plenty of room with a 16T or even 18T outer shell. But it will required some new production tools and a big investment.

Another possibitily would be to use the ratchet system (of DT Swiss) with a much bigger diameter. Maybe it would make more sense on the front, because this part of the bike has to deal with a huge load (frame around the bottow bracket, crank axle, cranks).

But both are not feasible, much to expensive for the trial manufacturers, sadly.

 

[matt slegg]

So talking about front screw on style freewheels only, does less engagements make them stronger?

[aener]

I think answering that will muddy understandings, so I'll make this as unambiguous as possible.

In THEORY, possibly, depending on how it was done. It almost certainly wouldn't be done that way, because it would be expensive to manufacture something different like that, and most people want as many engagements as possible so they wouldn't sell anyway.
In REALITY, today's 108/135 click freewheels are infinitely more reliable than the sub-30 click freewheels of yore.

If you're looking at buying a freewheel, do NOT base your decision on it having fewer engagements.
Go for whichever seems to have the best reputation at the time. What that is right now, I'll let other people discuss as the last time I looked at freewheels is was the Echo SL 108, but that was a long time ago. I've never tried one of the 135 clicks, or if the quality of the Echo has dropped or whatever.
If you can't reach a decision, give Tarty a ring and ask which seems the most reliable at present.

[US_BenR]

I miss King BMX hubs...they were the best.  

I also remember thinking ACS FWs were amazing, as almost 20 years ago (!) My first ride had one of thos Dicta freewheels, which had around 16 points of engagement.

 

[Al_Fel]

I think freewheels are stronger than freehubs because of how the forces are transferred.

The ratchet mechanism on a hub is offset to the chainline so when the force is applied it can all twist from the leverage of the axle and cassette carrier. I remember when I used to take my old hope bulb apart there would be teeth marks in the body around the pawls.

With a screw on freewheel you've got all that force going right down the centre evenly. There's no twist.

[Mark W]

32 minutes ago, US_BenR said:

I also remember thinking ACS FWs were amazing, as almost 20 years ago (!) My first ride had one of thos Dicta freewheels, which had around 16 points of engagement.

Likewise! Went straight from a Dicta to an ENO and felt like I could suddenly gap about a foot further. 

13 hours ago, La Bourde said:

As far as I know, there is two standards for screw-on freewheel: M35 (the most common) and M30 (still used on some cheap BMX, allow to have a 13T outer shell).

M35 isn't the standard one used for trials freewheels - it's 1.37"x24. There are some freewheels out there with a 1.375" (like the ENO) which is a bit closer to an M35 standard, but the thread pitch is quite different too. Trialtech make a rear hub (the Sport Lite M30) that uses the M30 standard.

Using a Shimano 24mm steel axle (best design by the way), it will let you 3mm on each side to fix the freewheel. And then you have plenty of room with a 16T or even 18T outer shell. But it will required some new production tools and a big investment.

IMO they'd benefit more from committing to basing it around an 18t profile. If you look at any freewheel out there now, there's typically a reasonable sized gap between the outside edge of the outer shell, and the minimum height of where the chain would sit on an 18t setup. By expanding the outer diameter, you'll get more 'usable' room to create a larger, better ratchet, rather than downsizing it to squeeze it in a smaller diameter area.

 

9 hours ago, aener said:

In THEORY, possibly, depending on how it was done. It almost certainly wouldn't be done that way, because it would be expensive to manufacture something different like that, and most people want as many engagements as possible so they wouldn't sell anyway.
In REALITY, today's 108/135 click freewheels are infinitely more reliable than the sub-30 click freewheels of yore.

Exactly that  The reason that most cheap freewheels don't have many engagement points is purely a cost limitation. To get higher engagement, you need more pawls that are much better machined, and more intricately machined ratchets (and better quality springs too). That all bumps costs up significantly, but also improves durability for the most part thanks to the more consistent, reliable engagement and better supported outer shell. That's why most cheap freewheels die fairly quickly for trials use. If you compare the pawls from a Tensile 60-click freewheel (top) to something like those from the Crewkerz (middle) or ENO freewheels (bottom), you can see even at that kind of level there's quite a difference:

On the Tensile one, I got to test an early prototype of the Tensile 96 click freewheel that had the same pawls as the 60 click one just a change from the 20-tooth ratchet to a 32-tooth. It skipped frequently no matter what I did, and it turned out it was down to the tip of the pawl needing to be changed to get into the finer ratchet profile. They ultimately changed the pawls between the two models of freewheel and that solved it. That's why the Tensile pawl above can have a much more rounded tip compared to the squared off tips of the others, simply due to the more precise tips required to engage in the finer toothed ratchets. The inside of the Echo SL freewheel shows how much more precise they need to be:

 

[La Bourde]

You know you made the bike nerd inside me really happy?

 

I read a while ago from the guy behind ACSE that the profiles of the pawls/ratchet are really important. He said basically than a freewheel/freehub with more engagement might feel slower(or less defined) than a another one with slightly less (e.g. a "bad" 72 clicks vs a good 60 clicks freewheel).

I read too, that I9 industries used the flexibility of the axle to augment the contact path between the pawls and the ratchet on their hydra hubs. To me, it sounds like you thing you have a  0.52° engagement, but at then end it feels like having a 2° engagement under your feet.

In addition, C. Gugliotta, the guy behind Crewkerz, prefers to have a chain tensioner to maintain the chain tension constant. He said without chain tensioner, you will either wear your bearing quickly or you lose more than a degree of engagement. I fully agree.

 

According to me, having a high qualitiy 72 clicks freewheel is for street/trial sufficient (or a pro ss 4 hub). There is already some play one the rear wheel due to the disc brakepads moving 

For trial comp riders, I think more is better, cause the drag is almost irrelevant.

[Mark W]

29 minutes ago, La Bourde said:

I read too, that I9 industries used the flexibility of the axle to augment the contact path between the pawls and the ratchet on their hydra hubs. To me, it sounds like you thing you have a  0.52° engagement, but at then end it feels like having a 2° engagement under your feet.

I've got the Hydra hub. It feels absolutely instant. There is the principle of them using the flex while it engages, but that's only to get the full compliment of pawls engaging. The ratchet is so fine and there are so many well defined pawls that to go from one to the others being engaged there's almost no perceptible movement. It's an amazing hub! 

Christian certainly talks a good game... I'm not sure I'd really agree with that assessment of sprung vs. 'other' tensioner systems though. From riders who've gone from an Arcade to the Fourplay or Hex, the difference in 'feel' is noticeable. The Arcade (horizontal dropouts with chain tugs) drive train feels super responsive, whereas the sprung tensioner bikes tend to not feel quite as immediate. Similarly, the Echo frames which had their integrated chain tugs seemed to hold up fine and offer really great feeling engagement, freewheel/crank/sprocket concentricity permitting. That concentricity issue is what I would use as a selling point for a sprung tensioner, not really to do with it 'saving' your bearings.

Sorry if this appears to be confrontational or anything, I'm not intending it that way  

[La Bourde]

Thanks for this answer Mark.

I like when someone has a different opinion, we are here to discuss! 

 

[Swoofty]

On 1/19/2021 at 6:59 AM, Mark W said:

Christian certainly talks a good game... I'm not sure I'd really agree with that assessment of sprung vs. 'other' tensioner systems though. From riders who've gone from an Arcade to the Fourplay or Hex, the difference in 'feel' is noticeable. The Arcade (horizontal dropouts with chain tugs) drive train feels super responsive, whereas the sprung tensioner bikes tend to not feel quite as immediate. Similarly, the Echo frames which had their integrated chain tugs seemed to hold up fine and offer really great feeling engagement, freewheel/crank/sprocket concentricity permitting. That concentricity issue is what I would use as a selling point for a sprung tensioner, not really to do with it 'saving' your bearings.

I've owned both sprung and chaintug bikes, but I've never noticed the slightest difference in engagement responsiveness between the two. Is that really a thing? When you punch the pedals, the 'top' chain does all the work and no matter what tensioner you have, that's a direct link from cog to sprocket with no tensioner in between. I much prefer sprung tensioners now because of the shortest possible chainstay they allow and I think the little extra wrap on the cog some of them allow limits flex in the system too.

[AdamR28]

7 hours ago, Swoofty said:

 Is that really a thing? 

Absolutely - the first pressure on the pedals has to straighten out / remove sag from the top part of the chain, before the drivetrain engages.

Clearly this is only when you have the chain a bit slack (ie. not set up properly) though, something French riders seemed to have an issue with a few years back 

[Swoofty]

17 hours ago, Adam@TartyBikes said:

Absolutely - the first pressure on the pedals has to straighten out / remove sag from the top part of the chain, before the drivetrain engages.

Oh sure! I hadn't considered that. Guess that's why I've never noticed it because my rig is always tight ;-)

[La Bourde]

On 28.1.2021 at 10:23 AM, Adam@TartyBikes said:

Absolutely - the first pressure on the pedals has to straighten out / remove sag from the top part of the chain, before the drivetrain engages.

Clearly this is only when you have the chain a bit slack (ie. not set up properly) though, something French riders seemed to have an issue with a few years back 

Horizontal dropouts are OK, but how many bikes have a chain tension that varies during a full rotation? Maybe this is because I always hit my bashgard, I don't know, but I never had a tension that seemed to be constant.

Also the tolerances in the bike industry are often so bad ... If you ever build a Shimano crankset on a Nicolai, Morewood or Last, then you know it is possible to have cranks that spin freely.