touring gearing

[Edwards]

I have a question if you do not pull down on the bars and stand on the pedals then to me you are only lifting your own weight, as in walking up a set of steps.
As there is no impact how can this be that much damaging to the knees? ( assuming you are not realy overweight)
Would a good exercise in strengthening the leg muscles simply be walking up lots of stairs?

[Trigger]

And,no,justb becvause you have an MTB you can't use it for touring...

Why not? if anything, with a few simple alterations, it's as good a "touring" bike as any normal person is likely to need. Unless of course you're a fashion victim and simply can't be seen touring on anything less than a crusty 1950's Galaxy with similar aged moth eaten Carradice panniers.

just like you wouldnt take your family on holiday in your caterham 71
R

That's the first time I've seen an MTB compared with a Caterham, what an odd comparison

[andrew_s]

I have a question if you do not pull down on the bars and stand on the pedals then to me you are only lifting your own weight, as in walking up a set of steps.
As there is no impact how can this be that much damaging to the knees? ( assuming you are not realy overweight)
Would a good exercise in strengthening the leg muscles simply be walking up lots of stairs?

a) you are stepping higher than on stairs, so your knee is more bent when you start pushing.
b) you don't walk up stairs anything like as much as you ride up hill. I dare say you'd run the risk of sore knees if you walked up the stairs to the top of the Gherkin 20 times without any practice.

Yes, stairs would be good exercise, but see (b)

[BigG]

I am a keen fan and user of low gears but there does have to be a limit, doesnt there?

Is that limit 18"?

I suppose somebody could do the maths to see what gear could let you do 3mph at 100 cadence rate, which would be pretty extreme.

3 mph with a hill-climbing cadence of 60 (not a cadence of 100as mentioned before in this thread) is a reasonable bottom gear. This is equal to about a 17" gear. It is hard to maintain a much slower cadence than 60 when climbing at low speed because of the lack of forward momentum and the top and bottom dead centre issue. Also, riding at 3 mph is about the slowest speed at which you can maintain a good straight line when climbing steeply.

[Edwards]

a) you are stepping higher than on stairs, so your knee is more bent when you start pushing

I think that may depend on how you ride standing up. If you push down slowly with the knee yes you are right. If you push more jump up to get the leg straight quickly, then let your body weight do the work I am not sure. Whenever I have walked up lots of stairs (20 floors) it was never the knees that gave problems.

[CJ]

In fact, if you think about this, low gears are a modern phenomenon brought about by MTBs. Cyclists used to tour on 3sp SA not many years ago, and even when derailleurs became common place, the range was limited.

Not so. The MTB pioneers fitted the TA triple chainsets that were already commonplace on the bikes used by French and other well-informed cycle-tourists. They also borrowed our cantilever brakes.

But low derailleur gears go back even earlier than that. According to Frank Berto's classic book "The Dancing Chain": the 1933 Funiculo derailleur could handle a 40-tooth sprocket. And not just handle it but shift "precisely and promptly" thanks to a double-sprung action similar to that invented half a century later by Huret in the Duopar.

Frank also describes gears of 22 to 80 inches achieved with a "1930s half-step plus granny" triple chainset and 4-speed freewheel arrangement, as used by British cycle tourists at that time. And Frank REALLY knows his history.

All this was of course beneath the contempt of elitist racing cyclists of the day, and since the noise of competition drowns out all other cycling voices, it is endlessly repeated and hence generally believed, that tourists have to thank another kind of racing, i.e. mountain-biking, for their low gears - oh, and their good brakes.

I hope that just a few of you will now join me in giving the lie to that factoid whenever they see it repeated.

Fact is, MTBs took our wide-range gearing and cantilever brakes, chucked them around a bit and made them some ways better, other ways worse (that is less and less compatible with the dropped handlebars some tourists still prefer to use) then leave the remains for us to pick over.

[fatboy]

Just come back from some serious hill climbing touring and low gears are great! The climbs of the weekend were Greenhow Hill (out of Pately Bridge), Fleet Moss, Buttertubs Pass, Tan Hill and Hartside. All bar the last one I used my 18" gear. I wasn't touring with much weight (around 10kg extra) but I'm not light (around 80 to 85kg) on a touring bike. I climbed quicker and easier than my travelling companions who all had higher gears.

Things that occurred to me when grinding up some of the hills was that there is nothing near where I live that can prepare me for "big" climbs meaning that my fitness is not tuned to hill climbing. Also I like to spin rather than grind. I'm also bloody minded to not get off and walk!

Now the compromise that I've got is that I've got a huge jump between the middle front ring and the granny cog which can lead to a loss of momentum under certain circumstances. If only I could get 22-32-44 to work with my road mech and STI levers I'd be really happy.

[CJ]

Now the compromise that I've got is that I've got a huge jump between the middle front ring and the granny cog which can lead to a loss of momentum under certain circumstances. If only I could get 22-32-44 to work with my road mech and STI levers I'd be really happy.

Increase the middle to 34T and it should STI with a Tiagra mech. My Stronglight 24-36-46 is perfect with Tiagra mech and STI, so to be more certain of success you might increase both middle and outer to those sizes.

The 22 inner being a couple teeth smaller than mine should be no problem, although the increase in middle size from what you're used to increases the falling into the void sensation you already have a bit of a problem with. The answer to this is learn to simultaneously click the left and right levers, shifting up a sprocket (or two) as you go down a ring, and vice-versa.

Don't worry about the chain flapping about even more and flopping off. These shifts happen on opposite sides of the chain and although a ripple transfers forward as the rear shift completes, the front should be home before that arrives. I learnt to make simultaneous front and rear shifts back in the 70s, when indexing was no more than a twinkle in Mr Shimano's eye, and I've not found it to increase the risk of dropping the chain one jot or iota. Back then however, it was tricky to finger-claw the right-hand down-tube lever forward exactly the right distance to upshift two cogs, whilst thumbing the left lever down to it's stop with the same hand, so I wouldn't have expected many people to even try it. But now we have indexing anyone can do it. So go on - be a double-shift devil!

[fatboy]

Increase the middle to 34T and it should STI with a Tiagra mech. My Stronglight 24-36-46 is perfect with Tiagra mech and STI, so to be more certain of success you might increase both middle and outer to those sizes.

The 22 inner being a couple teeth smaller than mine should be no problem, although the increase in middle size from what you're used to increases the falling into the void sensation you already have a bit of a problem with. The answer to this is learn to simultaneously click the left and right levers, shifting up a sprocket (or two) as you go down a ring, and vice-versa.

I might look into that. It's a sora front mech (and I've got sora STI with NO trim) but 22-34-44 would be a good set of gears (I only ever use my top gear (currently 48-11) for flat out down hill). A quick google has found 34t 104mm BCD and 44t is a standard shimano size.

Does the front mech mind having a gear that is so much smaller than the 52 that it's been designed for?

[fatboy]

My Stronglight 24-36-46 is perfect with Tiagra mech and STI, so to be more certain of success you might increase both middle and outer to those sizes.

The chainset values seem similar to a recently reviewed touring bike! Did your son get a Hewitt tourer then?

[CJ]

Does the front mech mind having a gear that is so much smaller than the 52 that it's been designed for?

No, it says it's perfectly happy about that. But thanks you for your concern and sends you this picture of itself.

Tiagra mech on 24,36,46

As you can see, the mis-match in curvature results in a tapering clearance between cage and outer ring. This is the recommended 1 to 3 mm at the front only. At the back it's way more and the bigger the gap, the greater the risk of the chain jumping through it during an upshift and ending up wrapped around the crank, so to keep it to a minimum I like the gap at the front to be nearer 1mm. I think it's about 1.5mm here and the chain has never overshifted yet. I cannot say whether or not another 2T mismatch from fitting a 44T outer, will open the rear gap enough for this problem to occur.

You can also see how close the bottom of the inner cage is to the middle ring. That's what delivers those crisp upshifts from inner to middle, and of course the proximity of the outer cage to the middle ring ensures those leg-saving downshifts from middle to inner.

In this photo it looks like 10T may be too little outer-middle difference for this mech, designed as it is for 11T, since the inner cage is a tad lower than the middle ring teeth. However the cage swings up a bit as it shifts outwards and it actually clears the midlde ring teeth by about half a mm when the outer ring is engaged. In this photo you can also see how the curvature of that inner cage exactly matches the profile of this 36T ring - even though you'd expect the cage to be less curved, befitting a 39T middle. So I think that if the chainrings were generally bigger, you would need to set the front mech a bit high in relation to the outer ring, in order to get away with a 10T outer-middle difference. If the rings are generally smaller however, that'll not be a problem. So 22-34-44 should be okay with regard to the middle ring.

And like I said before: inner rings are just down there, they seem to take what's dropped onto them okay regardless of how long the drop. But if overshift onto the bottom-bracket should become a problem - and it can be even when everything is exactly according to specification - simply fit a Jump-Stop.

[reohn2]

.........Increase the middle to 34T and it should STI with a Tiagra mech. My Stronglight 24-36-46 is perfect with Tiagra mech and STI, so to be more certain of success you might increase both middle and outer to those sizes.

+1 ,I also have two other bikes with 26-36-48 with Ultegra f/mechs (similar to Tiagra) that work flawlessly.Both tandems have similar set ups with Ultegra and 105 f/mechs and 26-38-48 which also are flawless too.

[CJ]

My Stronglight 24-36-46 ...

The chainset values seem similar to a recently reviewed touring bike! Did your son get a Hewitt tourer then?

Well spotted! The Hewitt is indeed now resident with Matthew in Montpellier. And to mark the handover we went for little ride over a local mountain. Here's a photo:


Matt and the summit by Chris Juden, on Flickr

And here's an illustration of how a 19-inch gear makes it quite easy to get right up the inside of that final hairpin!

[fatboy]

"I liked it so much I bought the" spa tourer!

A mate of mine is about to buy one and was amused when I suggested that I had evidence that you'd bought it!

[CJ]

.........Increase the middle to 34T and it should STI with a Tiagra mech. My Stronglight 24-36-46 is perfect with Tiagra mech and STI, so to be more certain of success you might increase both middle and outer to those sizes.

+1 ,I also have two other bikes with 26-36-48 with Ultegra f/mechs (similar to Tiagra) that work flawlessly.Both tandems have similar set ups with Ultegra and 105 f/mechs and 26-38-48 which also are flawless too.

Careful with that one. It depends on what vintage of Ultegra front mech we're talking about. Old 9-speed mechs are fine, but when Ultegra went 10-speed it got the same triple chainring sizes as Dura-Ace and a front mech with a super-extra-deep inner cage - that's designed to cope with a yawning 13T outer-middle difference!

It does work, somehow, on it's dedicated 30,39,52 chainset thanks to Shimano's gap-toothed and short-toothed tricks that make the chain really want to derail off to the left, and when the chain is reasonably new at least. But that inner cage is so much deeper than the outer cage that when the outer cage is trying to deflect a worn chain off teeth that are necessarily something like half a mile away from it, so as to get from middle to inner, when you're already on the hill so you can't ease up enough to take the tension off that piece of chain, well - you know what happens - or doesn't! You've all either experienced it or seen a companion heaving grind-grind-grind - oh-no I'll just have to get off and push!

My advice with triples is to keep the middle ring size as close to the outer and hence to the mech as the mech will allow. I'm not a fan of the move from 10T outer middle difference to 12T on mountainbikes that happened a few years ago. It spaced the three gear ranges more equally but at the cost of a less reliable middle-to-inner shift. To my mind the 13T Dura-Ace and Ultegra 10-speed difference is a step too far. I think Shimano realise that which is why 105 10-speed has an 11T difference. So if you're running 10-speed and want to ring some changes in the chainset department, I'd always specify a 105 triple mech and hope to get away with a 10T outer-middle difference. If not indexing I might even use a Campag triple mech instead, which by my measurements looks good for 8T.

Why make my middle that close in size to the outer? Because I NEVER want to find myself unable to shift the inner ring.