Road links and derailleur capacity

[Brucey]

re chainsets, a 130BCD chainset inner (or only) position can be turned into a 130/74mm BCD fitment if you use one of these things

https://www.spacycles.co.uk/m2b0s149p1141/STRONGLIGHT-130-74-BCD-Adaptor-ring

Note that many chainsets will require that you remove spider shoulders to allow fitment of the adaptor, and on HTII type ones, you have to be sure there is enough room for the new chainring, and that it won't clout the chainstay.

You could (say) use a 39/24 this way, which would give you a manageable front shift and a huge gear range.

http://ritzelrechner.de/?GR=DERS&KB=24,39&RZ=11,13,15,17,19,21,24,27,31,35,40&UF=2170&TF=90&SL=2.6&UN=KMH&DV=gearInches

shows what a 39,24 / 11-40T 11s setup looks like. Gears from 16" up to 96", with good 'tapping along' gears using the 15, 17, 19, 21T sprockets on the big ring with reasonable chainlines.

Also makes sense as a conversion from double to triple, obviously.

cheers

[Samuel D]

Using a cassette that starts at 14T, as proposed, will help the shifting at that end of the cassette with the RoadLink fitted.

With a tiny inner chainring, you’re very unlikely to use small-smallish gears (they’d be inefficient at power transfer for a start). So if the chain goes slack there, is it a big deal? I’d certainly make sure the chain is long enough for big-big regardless of what happens with small-small.

[rogerzilla]

Is there a reason you're not just going for a triple?  You can easily get 22 x 32 or 22 x 34 with standard MTB parts.  I know triples are unfashionable but so is cycling long distances...

I've never been fussed about having enough chain for big-big on a double or triple, and it was SOP to run road rear mechs on MTBs in the early 90s for better shifting, lighter weight and less chance of picking up twigs.  They would probably lock up if you selected 46 x 30 but no-one but a complete newbie would do that, surely?

[LittleWheelsandBig]

There aren't any good triple STI/ Ergo/ etc. levers being made now, particularly if you want to use electric (Judas!) shifting.

I never cross-chained with thumbshifters or downtube or barend levers either but STI can make it more difficult to tell (tired, dark, etc.) nowadays.

[quixoticgeek]

Is there a reason you're not just going for a triple?  You can easily get 22 x 32 or 22 x 34 with standard MTB parts.  I know triples are unfashionable but so is cycling long distances...

Di2 triple doesn't exist.


J

[phantasmagoriana]

Triples don't exist in 11 speed, do they? I've got a standard 50/34 compact and an 11-40 cassette on one of my bikes, with a Roadlink. It works, though the chain is a ridiculous length. However, I'm vaguely curious about these rings, which seem to promise a 46/30 setup on standard Shimano 4-arm cranks.

[quixoticgeek]

Triples don't exist in 11 speed, do they? I've got a standard 50/34 compact and an 11-40 cassette on one of my bikes, with a Roadlink. It works, though the chain is a ridiculous length. However, I'm vaguely curious about these rings, which seem to promise a 46/30 setup on standard Shimano 4-arm cranks.

Getting 46/30 isn't the issue. Having enough capacity in the rear mech, if using road, or having enough capacity in the front mech if using mtb. Whilst using Di2.

J

[Samuel D]

Deliberate big-big cross-chaining can be useful for short periods (Alberto Contador made it his trademark), but you can also accidentally get into it and cause damage if the chain isn’t long enough.

A slack chain does no real harm by comparison. Besides, small-small gears are useless and so I never get anywhere close to small-smallest where the chain would be slackest. Doesn’t Di2 do this thinking for you anyway?

[quixoticgeek]

Deliberate big-big cross-chaining can be useful for short periods (Alberto Contador made it his trademark), but you can also accidentally get into it and cause damage if the chain isn’t long enough.

The impact of big/big cross chaining seems to be a subject of debate a bit like vi vs emacs.

On my current bike I often seem to cross chain from big big, and I've not noticed any major issues. I've only ever done small small cross chaining because I've forgotten to swap up to the big ring.

A slack chain does no real harm by comparison. Besides, small-small gears are useless and so I never get anywhere close to small-smallest where the chain would be slackest. Doesn’t Di2 do this thinking for you anyway?

Yes and no. It depends how you set it up, and what control method you want to use. If you have syncro shifting setup, then it will swap rings somewhere in the middle of the range, to avoid cross chaining.

J

[jiberjaber]

Example synchro configuration shown. It's flexible but within certain limits.

[rafletcher]

One caveat with Di2 syncro, is that the set-up demands that you select chainring combination, and cassette range - both of which are AFAICR fixed to those combinations Shimano supply. These selections automatically set certain limitations on syncro shifting I think.  So with a radically non-standard setup such as is being considered here that might be sub-optimal and manual shifting might be the only sensible way to go.

I haven't used MTB Di2, so don't know how that works, or how the e-tube software determines if you have road or MTB cassettes/chainrings, as I'm pretty sure (again, I have only just though of this so haven't checked) with my road going setup there weren't any MTB casettes listed in the software - but as I wasn't looking for them I may have missed them! It may well be reading the firmware of the mechs to do initial set-up, and if so will offer different selection criteria to road Di2.

[jiberjaber]

One caveat with Di2 syncro, is that the set-up demands that you select chainring combination, and cassette range - both of which are AFAICR fixed to those combinations Shimano supply. These selections automatically set certain limitations on syncro shifting I think.  So with a radically non-standard setup such as is being considered here that might be sub-optimal and manual shifting might be the only sensible way to go.

I haven't used MTB Di2, so don't know how that works, or how the e-tube software determines if you have road or MTB cassettes/chainrings, as I'm pretty sure (again, I have only just though of this so haven't checked) with my road going setup there weren't any MTB casettes listed in the software - but as I wasn't looking for them I may have missed them! It may well be reading the firmware of the mechs to do initial set-up, and if so will offer different selection criteria to road Di2.

Yes - this is correct however you can use what ever you have on the bike itself but then use some mental gymnastics to set the shift points on the DI2 - so in the picture I posted above my bike actually has 46/30 with 11-34 but you are limited by what Shimano says can be the combinations in its software.  Also, selecting certain combinations within the app limits where you can move the shift points.  You can never set big-big - in the example picture the DI2 will shift from 50/28 to 34/18 when you try and shift to 50/32. 

[Brucey]

there is at the heart of this an almost philosophical debate to be had about equipment selection for the intended task. On the one hand there is 'equipment performance'  and on the other hand there are 'what ifs?'.

So a major "what if?" is what happens if you have a problem of any kind.  You have to factor in how likely this is to occur and how easy it is (for you, at that time) to fix it.  I don't know what proportion of TCR riders have major equipment problems that thwart  them, but it is worth looking at those that do and asking if the performance gain would be 'worth it' or not.

I was peripherally involved in one would-be TCR rider's preparations a couple of years ago and they had chosen a setup with a hub generator backing up a Di2 system.  That wouldn't have been my choice; there were wires trailing about all over the place, looking as if they would get snagged and broken very easily. In fact there were so many wires that all kinds of normal maintenance tasks would have been very difficult to do without disturbing a lot of the wiring.  In the event of trouble I am quite sure that the rider would have been pretty well stuck, and spares would not be had locally.

For me this would outweigh the possible advantages that this system might offer. I'm sure others would be able to rationalise their choice in their own way; for example I have heard others say that 'they wouldn't be able to fix a Bowden cable either so it makes no difference to them' but I think this is a deeply flawed argument. 

As it happens none of this mattered anyway in that particular case; the chap with the wires had to pack after a day or two because his knees gave up. 

cheers

[Kim]

there is at the heart of this an almost philosophical debate to be had about equipment selection for the intended task. On the one hand there is 'equipment performance'  and on the other hand there are 'what ifs?'.

[...]

As it happens none of this mattered anyway in that particular case; the chap with the wires had to pack after a day or two because his knees gave up.

This is my experience generally:  Reasonable component selection and vaguely competent maintenance means that the rider is by far the most likely point of unrecoverable failure.  You can't engineer around that other than by choosing better parents, or not to have been in that car crash 30 yeas ago, so if your choice of gears means your 60% chance of DNF becomes a 60.5% chance (but you get to keep your working fingers, or whatever else the perceived advantage might be), maybe it doesn't really matter?

I was peripherally involved in one would-be TCR rider's preparations a couple of years ago and they had chosen a setup with a hub generator backing up a Di2 system.  That wouldn't have been my choice; there were wires trailing about all over the place, looking as if they would get snagged and broken very easily. In fact there were so many wires that all kinds of normal maintenance tasks would have been very difficult to do without disturbing a lot of the wiring.  In the event of trouble I am quite sure that the rider would have been pretty well stuck, and spares would not be had locally.

IME a rat's nest of wiring is mainly a problem when the bike isn't being ridden.  These sorts of things (along with hydraulic hoses and bowden cables, and mundane stuff like handlebar grips) are vulnerable to being bashed with locks, or getting snagged on things when loaded into vehicles, but once you've made it to the start of the TCR, there shouldn't be very much of that going on.

I predict the most likely failure mode of a dynamo-backed-Di2 system is that the rider would have to seek out the use of a mains socket for a couple of hours in order to recharge the battery.  Effectively a loss of flexibility in sleep schedule, rather than loss of gears.

[quixoticgeek]

there is at the heart of this an almost philosophical debate to be had about equipment selection for the intended task. On the one hand there is 'equipment performance'  and on the other hand there are 'what ifs?'.

[...]

As it happens none of this mattered anyway in that particular case; the chap with the wires had to pack after a day or two because his knees gave up.

This is my experience generally:  Reasonable component selection and vaguely competent maintenance means that the rider is by far the most likely point of unrecoverable failure.  You can't engineer around that other than by choosing better parents, or not to have been in that car crash 30 yeas ago, so if your choice of gears means your 60% chance of DNF becomes a 60.5% chance (but you get to keep your working fingers, or whatever else the perceived advantage might be), maybe it doesn't really matter?

Ultimately what ever I do the big limiting factor will be the squishy bit between pedals and handlebars. The classic layer 8 weakness.

However, there are things that can be done to help the squishy bit. Being able to change into the right gear, easier, faster, and without having to change position means that you can reduce the strain on the knees. Being able to press simple buttons to change gear rather than having to move a lever, pulling against a cable that is getting increasingly draggy with each passing km, reduces strain on the hands, reduces the impact of the claw. 2 simple examples of how di2 can help with the squishy part of the bike/rider combo.

So you take the increased complexity of the control system, and offset it against the reduced impact upon the human. It's a trade off. Each rider will choose where this trade off is.

I was peripherally involved in one would-be TCR rider's preparations a couple of years ago and they had chosen a setup with a hub generator backing up a Di2 system.  That wouldn't have been my choice; there were wires trailing about all over the place, looking as if they would get snagged and broken very easily. In fact there were so many wires that all kinds of normal maintenance tasks would have been very difficult to do without disturbing a lot of the wiring.  In the event of trouble I am quite sure that the rider would have been pretty well stuck, and spares would not be had locally.

IME a rat's nest of wiring is mainly a problem when the bike isn't being ridden.  These sorts of things (along with hydraulic hoses and bowden cables, and mundane stuff like handlebar grips) are vulnerable to being bashed with locks, or getting snagged on things when loaded into vehicles, but once you've made it to the start of the TCR, there shouldn't be very much of that going on.

The rats nest is one that is a bit over talked about. And, given the bike in question, will be limited due to internal routing. If there is an issue with the cabling breaking. It is my intention to carry spare cables, and spare junction b, so I can bodge an alternative wiring route externally if needed. Just the same as I carry spare bowden cables on my current bike. I have an embedded electronics back ground, so such things are second nature to me.

I predict the most likely failure mode of a dynamo-backed-Di2 system is that the rider would have to seek out the use of a mains socket for a couple of hours in order to recharge the battery.  Effectively a loss of flexibility in sleep schedule, rather than loss of gears.

Eh what? You carry a cache battery, that charges, you get about 2-2.5Wh per hour of forward movement, but between all gadgets carried, you're going to be using more than the 20-25Wh of power per day, so the battery will diminish over time. But if you use the right battery pack (I have a specific Anker), charging of a battery pack is going to be part of your usual routine.

In my trial runs after a couple of nights bivvying, I arrive at a hotel, first thing to do is plug in the 4 way USB block, into this goes the critical devices, 1 battery cable, 1 wahoo, 1 irridium, 1 camera (this isn't critical, but it charges fast). Then I turn to the bike, oil the chain, do any other maintenance needed. Then it's to the shower to deal with hygiene routine, and far too much zinc oxide cream. By this time the wahoo and the camera are usually charged, At this point in goes the second battery cable, then the phone, then sleep. The battery is 98Wh, and can be charged fully in about 6.5 hours.

If you have electronics, they become part of the routine. Work out your power budget, work out what needs to be charged, how much power it needs, and how often. It's pretty basic. If you're having to stop at a time not of your choosing to do charging, it means you've screwed something up somewhere.

J

[Kim]

If you have electronics, they become part of the routine. Work out your power budget, work out what needs to be charged, how much power it needs, and how often. It's pretty basic. If you're having to stop at a time not of your choosing to do charging, it means you've screwed something up somewhere.

Yes, that was my point.  If your dynamo charging fails, you change your sleep schedule or shed some less-essential load (camera, twitterwebs, navigation) to compensate.  It's not a ride-stopper.

[amedias]

So a major "what if?" is what happens if you have a problem of any kind.  You have to factor in how likely this is to occur and how easy it is (for you, at that time) to fix it.

It's this logic that keeps em on a triple on my Audax bikes, despite being well maintained issues with gears or cables are a possibility.

With a triple any issue at the back end still allows me to lock in a gear halfway up the cassette and have 3 useful and usable gears at the front, with only extreme climbs potentially being an issue.

An issue at the front allows me to lock it into the middle ring and still have a useful range, where as a compact or wide double would leave me having to choose a chainring too big or too small for large portions of the ride.

And if nothing goes wrong I have the full range of gears I'm so fond of using. I normally use my triples as a 'double + bail-out' with the chain set to allow big-big but go slack on the granny ring and the smallest 3 or 4 sprockets as they are gears I'd never use anyway.

FWIW, as someone said above Shimano specs are normally a bit conservative. My wife is currently running a 46/33 compact up front, with a 11-34 at the back using a short cage Ultegra 6600 rear mech that was only ever rated to 27/28t max sprocket size! A bit more B-screw was needed but it shifts fine and the only gears not available to her are 33x11,13,15 which she never uses anyway as she's jumped back up to the 46t ring by then. I relaise that's not quite as wide range as you're after but if you use a long cage rear mech you'll gain a fair bit of capacity over the above setup, I reckon 46/30x11-36 would be no bother at all and possibly not even need the road link depending on how much B-screw you can wind on and the exact hanger length on your frame.

In your situation OP I'd not worry about the capacity too much and make sure it works big-big, and just let it run slack on the little-little combo which you should never use. Even if you do use it accidentally once or twice it wont do much harm and you'll realise quickly to change.

[Samuel D]

Did you reverse the B-screw to effect an extension or devise something more sophisticated? It’s an odd thread pitch if I recall correctly.

[amedias]

With my wife’s bike I didn’t need to, it just need screwing in a few more turns than was optimal, but I have reversed the screw on one my MTBs when it was at the limit and it gave just enough extra. Sram mechs I’ve fully replaced the screw with a longer one before but i seem to recall that being a fairly normal thread so was easy to source.

[Oxford_Guy]

There aren't any good triple STI/ Ergo/ etc. levers being made now, particularly if you want to use electric (Judas!) shifting.

One of the reason I'm for now sticking with renovating 2006-era Campagnolo Ergos (which work with both doubles and triples just fine)

[Brucey]

FWIW the rat's nest of wiring on the bike I mentioned earlier was worst around the handlebars. Again there is a conflict; keep it all accessible so that it can be fettled/repaired or hide it all so that it is less easily damaged (but more difficult to repair/maintain, obviously). There are always wires somewhere that get flexed/vibrated and even well specified ones can still fail.  I think that you are doomed to have exposed wires somewhere and these can get snagged. 

 One idea for mitigation of the snagging risk is to bind a reinforcement (eg braided nylon shot cord; in ~2mm form it has a breaking strength of something like 150lbs) to the crucial exposed wires using tape, and then tape the ends of the  cord to the frame/handlebars so that in the event of the wires getting tugged, the cord takes the load, not the wires. Some wires are (modestly) internally reinforced with strands of cord anyway, but there is little harm in adding more reinforcement this way.

Re 'staying in one position';  I have never found this a really good scheme. Once every few minutes I stretch, change position, ride out of the saddle or similar anyway, just to keep good circulation in every part of my body. Changing gear is just another  excuse to move around a bit, so I don't begrudge it.  BTW I don't find STIs especially comfortable to use (maybe back to the wrist thing?) and in many ways prefer a standard gear lever mounted somewhere handy.

As a general comment yes the big squishy bit is likely to be a main point of weakness, but to my mind this would only make me prioritise reliability and repairability over everything else when it comes to choosing equipment; you are going to feel doubly or even triply gutted if some equipment fault (that could maybe be easily fixed if you were in a well equipped bike shop) leaves you stranded in some remote location. As I mentioned earlier, looking at those riders on similar events who had equipment problems is worthwhile; their problems would have been some combination of bad luck and bad choices; telling which and making a rational choice isn't easy but there is more to be learned here than (say) what equipment a winning rider used.  A winning rider would have got some marginal gain from some equipment choices but others using similar equipment may not have finished the event at all.

cheers

[zigzag]

a few minor issues on my last tcr:

* two punctures on gravel and one pinch flat when riding over a piece of brick (all on the front wheel)
* power meter worked intermittently after a firmware upgrade done just before the race
* jockey wheels got squeeky towards the end (fixed with some oil but need replacing)
* usb cable to charge gps unit broke - had a spare cable
* handlebar gel pad on the right side got too squishy (because of heat?..) which loosened the bar tape
* broke the bottom of front mudguard off (crudracer2) - toe overlap on a steep climb
* one of the aerobar end plugs fell off somewhere
* saddle bag slid down the seatpost and worn through exposure tracer rubber ring
* garmin 500 crashed lots of times and lost a big chunk of the trip data (the fault was usb socked detached from the circuit board due to cable vibration - fixed when i was back home)
* due to heavy rain and dropping my bike on the sand (the wrong side) I've run out of chain lube and rode the last 1400km using vegetable oil from the restaurant, worked fine.

the main lesson i've learned from above is not to charge the electronic units on the go, unless they are wrapped in something soft together with the powerbank and cable. usb plugs do not have solid and stable connection to the sockets and constantly vibrate on a bike, wearing out the contacts and causing intermittent issues. i was glad with the decision not to take a dynamo wheel as this would have added another level of complexity, more wires and a potential point of failure (plus of course the drag).

gears (10sp 52/42/30 with 15-36) worked perfectly, although in the hindsight i should have used the standard 12-36 cassette.

[quixoticgeek]

FWIW the rat's nest of wiring on the bike I mentioned earlier was worst around the handlebars. Again there is a conflict; keep it all accessible so that it can be fettled/repaired or hide it all so that it is less easily damaged (but more difficult to repair/maintain, obviously). There are always wires somewhere that get flexed/vibrated and even well specified ones can still fail.  I think that you are doomed to have exposed wires somewhere and these can get snagged.

It's a balance, and each rider will find that balance in a different place. With typical bike packing setups where you have bags attached to the handlebars, this gets in the way of exposed wiring, having the wiring under the bar tape will also protect it.

But by having multiple shifters, be it the brake lever ones, climbing shifters, and then shifters on the tribars, if one fails, it's annoying, but not endex. Carry spare cables, and it should be possible to rejig things to make sure something works.

Re 'staying in one position';  I have never found this a really good scheme. Once every few minutes I stretch, change position, ride out of the saddle or similar anyway, just to keep good circulation in every part of my body. Changing gear is just another  excuse to move around a bit, so I don't begrudge it.  BTW I don't find STIs especially comfortable to use (maybe back to the wrist thing?) and in many ways prefer a standard gear lever mounted somewhere handy.

Yes, we all move around, but when you've just got comfy on the tri bars, and need to change gear, it becomes a pain, trust me, I've been running my current setup for 9123km so far this year. I am very closely acquainted with the quirks of the setup and what bugs me and what doesn't. Having to move off the tri bars to change gear is really annoying.

This is largely a matter of taste, each rider will do things different, each will find different things annoying. Cycling is a very broad church. There is no one right way.

As a general comment yes the big squishy bit is likely to be a main point of weakness, but to my mind this would only make me prioritise reliability and repairability over everything else when it comes to choosing equipment; you are going to feel doubly or even triply gutted if some equipment fault (that could maybe be easily fixed if you were in a well equipped bike shop) leaves you stranded in some remote location. As I mentioned earlier, looking at those riders on similar events who had equipment problems is worthwhile; their problems would have been some combination of bad luck and bad choices; telling which and making a rational choice isn't easy but there is more to be learned here than (say) what equipment a winning rider used.  A winning rider would have got some marginal gain from some equipment choices but others using similar equipment may not have finished the event at all.

You have to look at the setups used through out the race. Not just what Ede uses, but also what those who DNF'd used, what those who came in after the time limit, those who came in with hours to spare.

This is why I cycled through the night to be in Geraardsbergen, to talk to riders, to look at what they are running, talk to them about their decision making process, to take photos of the setups, to get inspiration. I didn't race this year, but being in the start was what cemented my decision to apply for 2019. I made friends with a number of riders who raced this year, and am still in contact with them, it's been really enlightening as to what did and didn't work.

There's one rider who was using a triple on a square taper bottom bracket, and she managed to crack the inner ring of her triple. Had to get it fixed in Switzerland. Finding a bike shop with the right part was hard.

And that's another key point. Bike shops are very much variable in their quality. On my scandi adventure last month, I had to go to several bike shops over a 100km distance to find one that was a) open b) stocked 700c inner tubes. Yes you read that right. 700c inner tubes were not stocked by one of the bike shops I went to. They had tubes for upto 23mm tyres, and they had them for 35mm and bigger, but nothing in the middle.

I'm very much working on the assumption of being totally self sufficient mechanically.

J

[grams]

I wouldn't connect a Di2 system directly to a dynamo if only because Di2 just doesn't need that much charging. You're also exposing two fragile, non-waterproof connectors (at either end of the Di2 charger) to the elements. Much better to plug it into a power bank (or wall) a few times during the ride.

But I concur with Kim that cables are much more likely to be broken while stored than riding. I have a bike with 964 animated LEDs on it that is nothing but rat's nest. I don't think anything has ever broken on it *during* a ride, but I expect to find the cables on it are damaged whenever I dig it out of storage.

(in fact the only part that conflicts is the mechanical gear cable rubbing on the head tube. Perhaps I should install Di2?)

[Brucey]

in fairness I have ridden thousands of miles on tri bars and on bikes where that was the main position I had the shifters mounted on them, mounted so that I only had to move my fingertips to shift.  When I wasn't using the tribars (eg when climbing) I didn't mind moving my hands the required short distance to the shifter. I daresay I might feel a bit different about that if I had grown up with different shifters from the start. DSFDF and all that.

BTW I was also careful to use shifters that had a back-up friction mode in some uses. I have (on various bikes) had to use this a few times, eg because the RD has taken a knock. On cable-operated systems having a barrel adjuster within reach may spare you from having to dismount and fiddle, but a switchable friction mode means you can change over (on the move) and carry on regardless, albeit that you might not be able to use the end sprockets cleanly/safely. [It also allows you to shift on a replacement wheel with a completely different number/spacing of sprockets, too.]

 I am not sure what you would (or could) do with a Di2 system if (say) the RD gets a bit bent; in some cases with standard mechs that are bent indexing just stops working (even if you can trim things to make any one gear run quietly) and you need some kind manual intervention (eg overshifting) to make shifts.

It is interesting that you couldn't find middling width 700C tubes.  I think that may be because most people either have 'a road bike' or 'a hybrid'.  On that basis it might make sense to use a bike that can use the lowest common dominator wheels, too; at least you will be able to find a replacement easily in the event of a prang.

cheers