Bicycle Mechanics - Why not use 9/10 speed tech to reduce dish?

Ok, so this is coming from someone without too much knowledge, so I'm probably missing something basic.

On an old 10 speed bike, there are 5 sprockets on the rear hub. On a new bike, there can be 10, TWICE as many. Obviously this is because the stack of sprockets must now be thinner per sprocket. The new setup has the advantage of smaller tooth differences from lowest to highest, offering more gear choices.

My question is why don't we ever see rear wheels with 5, widely spaced sprockets of the modern, thin variety? The purpose behind this could be to use all that extra room on the rear hub to widen the space between the flanges, reduce wheel dish and have a much stronger rear wheel. Is the desire for durability over fine gear selection just too uncommon for this setup to be available? I'm especially surprised I don't see this on mountain bikes, which definitely could benefit from stronger wheels- and considering the popularity of singlespeeds, fine gear selection must not matter TOO much. Thoughts?

My thoughts exactly, but the market is probably too small.

Back when we could use freewheels based on 3 speed and 4 speed bodies, we did just that occasionally. Nowadays, the 9 and 10 speed cassettes are only sometimes compatible with hubs down to 7 speed width, with no easy way to reduce the width of the stack below that.

Most of the work on balancing the strength of the wheel has come on the other side, with longer axles on the left side and left flanges moved in a bit to better balance spoke tension, even though bracing angle is reduced.

Well, they do that already - to a point. Mountain bikes use a wider rear hub spacing to gain an extra 5mm of space and they don't use 10 speed cogsets (yet).

If you're riding a long flat road, it's nice if you can find a gear that's right in the sweet spot. That way you don't feel like you're pedaling too hard or having to spin your feet too fast. I think that a majority of riders appreciate close ratio cogsets.

First, 5-speed dropout spacing was 120 mm and 8/9/10-speed road dropouts are 130 mm (MTB's are 135 mm) so the dish increased isn't nearly as much as you think. Second, spokes, hubs and rims are much improved in quality over what was available in the 5-speed era so wheel strength isn't nearly as much of an issue.

If 9/10-speed wheels were collapsing frequently, I guess we would be looking for a cure. They aren't and we aren't.

First, 5-speed dropout spacing was 120 mm and 8/9/10-speed road dropouts are 130 mm (MTB's are 135 mm) so the dish increased isn't nearly as much as you think. Second, spokes, hubs and rims are much improved in quality over what was available in the 5-speed era so wheel strength isn't nearly as much of an issue.


I think the point was to use the modern width of 135 mm, but with a shallower cassette body holding just 3-5 sprockets, allowing the drive-side flange to be moved out by perhaps as much as 20-25 mm.

I think it's mostly because bicycles are sold by 'speeds' as in you need more speeds not less. If you look at 7-8-9-10 speed drivetrains, the obvious point should be range...as in a higher high and a lower low...but they are being marketed to have smaller steps between the gears not a better overall range. Do you really need ten steps between an 11 tooth cog and a 23 (25, 27, whichever)? In an 11-12-13-14-15-16-17-19-21-23 will you really notice any difference between a 14 and 15 tooth cog? I doubt it very highly.

Part of the problem is that bicycling, unlike other sports, allows you to buy the equipment that the pros use. You can go out and purchase, off the shelf, the same equipment that the world class guys are using today. You can't do that with other sports. When was the last time you went to Checker and tried to pick up a Formula 1 engine?

Bicycling is also a very small sport. There may be lots of people out there doing it but as a percentage of the population, it's still tiny. And the people that need stronger wheels, for example, are a smaller market still. So the pro segment ends up driving the market and we get lots of little steps between already tight gear ratios.

Maybe there's hope when oil hits $200 a barrel:eek: Of course we'll all have to dress like this

http://www.davemillicanbelts.com/Large7/RoadWarriors.jpg

Looks too hot for riding to me;)

I think the point was to use the modern width of 135 mm, but with a shallower cassette body holding just 3-5 sprockets, allowing the drive-side flange to be moved out by perhaps as much as 20-25 mm.

yeah that's what I meant. I see I'm not the first person to think of this. :)

cyccommute, good points, my perspective on the possible 'need' for this was somewhat influenced by ideas of heavily loaded bikes. yknow once the cars are all gone.

but yes right now, I'm sure that retrogrouch is right and the majority benefit more from having more speeds.
hillrider, I had forgotten that dropout spacing has increased over the years. My old 10 speed is closer to 130 than 120 though. maybe it got bent or something.

it doesn't seem like it would be very hard for shimano to make an appropriate hub, if they wanted to.

There's always the option to go find someone with the equipment to modify a hub. Cut the hub shell in half and weld an insert, then find some way to shorten the cassette body while keeping the internal bits working. After that, just disassemble a cassette and mount the sprockets you want/need (doesn't work for the lighter cassettes that have a common "frame" for the largest 4-5 sprockets).

hmm, what you just said made me think. I wonder if you could create a 'flange sprocket' that you could slide onto the splines with some spacers behind it. Put the spokes through that, then put the the cogs on. possible you think?

" it doesn't seem like it would be very hard for shimano to make an appropriate hub, if they wanted to."

It wouldn't, but how big of a market would there be for it? Quite small, which would make it expensive. Since you have to spend the extra money, it makes more sense to invest that money in a stronger wheel and keep your gears.
Although many people are totally content with "wide range" gearing, others that ride the flat lands like a lot of closely spaced higher gears.
I have bad knees, and thus find my cadence to work best in a rather limited range. I love being able to shift to a 1 tooth different cog if the headwind changes slightly, and repeat if it changes a bit more. Currently, my largest cog is a 23T. (12-13-14-15-16-17- 19- 23)

ive had the same thought many times, but not necessarily for a stronger wheel, but more for more direct power transfer resulting from a chainline which doesnt deviate nearly as much off centre, and gears being more closely condensed near the right hub flange. I rode my Litespeed Vortex for a year or more with a single 42 tooth chainring, and only six gears in the back on a 9 speed cassette body, 11-16 teeth. this worked remarkably well, as i lived in Florida at the time and only commuted with the bike daily. all the spacers were on the outside of the body, after the cog cluster. this resulted in good chainline, but the extreme dish of the 18 spoke Mavic wheel still existed, and no doubt less dish would mean more uniform spoke tension which means spoke breakage due to under tension is less likely.

I'd love to have an old Italian 126-spaced frame with a 9 speed cluster using modern 10 speed-width components. Cold-setting frames scares people, so i actually think there would be a market for this type of thing. oh well, i'm broke so i can't do anything about it.

Actually I've seen this done by someone posting on mtbr.com. Try searching the 29er forum, but I'm positive I've seen at least one person with a paired-down cassette and single chainring. I don't know if they used a single speed hub and went from there or somehow redished a modern hub, but maybe it's worth starting a thread asking about it if you can't find the posts I was talking about. I like browsing the 29er forum because apart from the larger wheel size a lot of those guys seem to be pretty creative in the way they set up their bikes.

hmm, what you just said made me think. I wonder if you could create a 'flange sprocket' that you could slide onto the splines with some spacers behind it. Put the spokes through that, then put the the cogs on. possible you think?

Hmmm... possible, I would think that if you did this the best result would be if you made it just a little tight, and fitted it hot.
Any movement of the part would tend to change spoke tension. Maybe weld it in place?

As far as the whole idea of straight chain lines and more even dish, why not just get Rohloff hub? That way you don't even have to give up the gears.

heh. oh boy. I just realized that what I said before makes no sense- I forgot about where the freewheel is. oops. As for the Rohloff, it would be nice, but so much money. internal hubs in general would do the job of eliminating dish, of course. I recently turned my 10 speed into a sturmey archer 3 speed, actually. (More for experimentation than any real need for superstrong wheels.) Working on my girlfriends bike today got me thinking about derailers, and I was thinking about how the derailer setup could accomplish the same results as the internal hub with simpler mechanics, etc..

Well, they do that already - to a point. Mountain bikes use a wider rear hub spacing to gain an extra 5mm of space and they don't use 10 speed cogsets (yet).
Just because there ain't a clicker for it doesn't mean I can't slap it on the bike.

Another issue that you will encounter is shifting. Indexing is no longer an option since 7,8,9 and 10 speed shifters pull the cable a determined amount. Which leaves you with friction. Paul (http://www.paulcomp.com/) makes a handy little clamp that allows you to attach downtube shifters on your handle bars. I had a set and my friend used it last year to make a three speed mountain bike (one chainring). He tried using a DXR freehub body (http://bike.shimano.com/publish/content/global_cycle/en/us/index/products/bmx_bike/dxr/product.-code-FH-MX70.-type-fh_mountain.html) but couldn't quite get three cogs to fit on it. So he just used a regular 9 sp. body.

On a side note I'm thinking about one day building me a 7 sp. road bike for commuting. I find that 53-39 is usually too high or too low for getting from A to B. This is way in the future, haven't done any real planning yet but probably go with 42 or 44 at the front.

Does the dish on a rear wheel really have that much affect on the strength of the wheel? Or is it really that much of an issue?

The old 5 cog freewheels had their own problems. But, I guess you could get a more neutrally dished wheel by squashing 5 modern thin cogs onto a short freehub body where the hub has more distance between the flanges. The wheel design book I have (schraner) makes no mention of dish having any affect on wheel strength. What has more affect is flange diameter, rim depth, spoke length, spoke count and cross. And you can do (and companies have) done funky things to mess with the first two. Deep section rims, asymmetric section rims and asymmetrically flanged hubs being just a few examples.

From what I've read the going theory is that spokes are the weak link in the system. You reduce that weakness by making the weak part shorter, and by causing there to be more weak bits to take up the load (more spokes is generally recognized as being stronger than fewer spokes). What exotic wheel companies have done, more often than not, is produce wheels with fewer spokes by making the rim stronger and heavier.

On the flip side, the average rider only ever uses 5 or 6 of the cogs in a 7 or 8 (or even 9) cog stack. Which IS a waste. But, the industry can't sell hybrids that don't have granny gears even if that granny gear never gets used. However, the argument for having tiny steps across a short range of gears holds on the fact that the work you put in a bicycle system is more efficient if you allow your engine (ie legs) to run at a more constant cadence while changing gears. For a demonstration of this, hop on a bike with the Shimano automatic shifting system (Trek Lime, Raleigh Coasting etc) and go for a pedal. It is hella jarring when that system shifts into a higher gear.

When building a dished wheel the side which has the smaller distance from the center to the flange can be tensioned 100%. Whether its 90 Kgf or 110 Kfg it doesn't really matter. The other side can only reach 60% to 70% of that tension. Since tension is not even you don't get as strong a wheel. It's still a good wheel but it's not as strong if the tension was balanced.

I'd love to have an old Italian 126-spaced frame with a 9 speed cluster using modern 10 speed-width components. Cold-setting frames scares people, so i actually think there would be a market for this type of thing. oh well, i'm broke so i can't do anything about it.

Well you are in luck! With a cable trick that you can get off of Sheldon Browns web site under derailleurs you can use any 10 speed road shifter to shift PERFECTLY using 9 speed clusters! I personally had to do this when a friends 10 speed wheel had a blow out, and we replaced the entire wheel with a 9 speed wheel I had in the garage. I changed his rear derailleur and he had perfect 9 speed shifting with one extra "dummy" shift. Now just cold set your frame! Or if you are scared of that, just spread the frame apart just enough to get the wheel in. (though this is actually weaker than cold setting). Ahh the possibilities!

Does the dish on a rear wheel really have that much affect on the strength of the wheel? Or is it really that much of an issue?
In theory, yes it does. In practice, with modern spokes, rims, etc. the theoretical disadvantage is not an issue.

Consider all of the boutique, low spoke count wheels being sold and ridden successfully these days. If weaking due to dish were a significant problem, they couldn't exist. 9/10-speed 130 mm wheels built with 32 or 36 spokes and good rims are very durable even under touring loads.

If you really want to eliminate dish, build a frame with 140 mm dropouts like a tandem uses.

If you really want to eliminate dish, build a frame with 140 mm dropouts like a tandem uses.

You have a point but I doubt you'll find very many tandems with 140mm dropouts. The generally accepted standard for tandems is 145mm. Santana tandems have (you may need to sit down) 160mm dropouts. 160mm dropouts allow for a disc brake, relatively wide spaced hub flanges for a better braceing angle, and a totally dishless rear wheel.

You have a point but I doubt you'll find very many tandems with 140mm dropouts. The generally accepted standard for tandems is 145mm. Santana tandems have (you may need to sit down) 160mm dropouts. 160mm dropouts allow for a disc brake, relatively wide spaced hub flanges for a better braceing angle, and a totally dishless rear wheel.
Yeah, I'm a generation behind with tandem components. OK, so 145 mm makes the dish even less of a problem.

I'm aware of Santana's 160 mm dropouts but I also know the idea never caught on with other tandem makers so, AFAIK, they remain the only user.

will you really notice any difference between a 14 and 15 tooth cog?

Yes I do.

I'm aware of Santana's 160 mm dropouts but I also know the idea never caught on with other tandem makers so, AFAIK, they remain the only user.

Do you suppose that's what makes their 16 spoke tandem wheel possible?

Yes I do.

And how big a difference is it? With a 50 tooth ring, changing from a 15 to a 14 at 90 rpm changes your speed by 1.6 mph. Increasing you rpms to 100 in the 50/15 combination will give you a larger speed increase (2.6 mph).

Do you suppose that's what makes their 16 spoke tandem wheel possible?

That's a new one on me. I wonder if the spokes are something like 10 gauge. I checked their web site and those wheels are on the bike shown on their home page but they don't give any construction details. I can't tell how heavy the spokes are but I'll bet they're not DT Revs. Also, the wheels, when available as a separate item, will be $1050!

More sprockets can be fitted for the reason that cassette hubs have the axle bearing out at the end of the cassette. Pre-cassette hubs have the bearing more in line with the flanges; ie the sprockets overhang the bearing and can't go out too far.

Dishing never was a problem because the axles just got longer.

That's a new one on me. I wonder if the spokes are something like 10 gauge. I checked their web site and those wheels are on the bike shown on their home page but they don't give any construction details. I can't tell how heavy the spokes are but I'll bet they're not DT Revs. Also, the wheels, when available as a separate item, will be $1050!

An acquaintance brought me one, along with a new rim and new spokes to relace for him. The spokes are aero section and pretty fat. My instructions said to walk the tension up to 95 on my Wheelsmith tensiometer. I'm thinking that must equate to around 150kgf. My fingers were sore by the time I had finished tensioning that wheel.