Yet Another Cycling Forum
General Category => The Knowledge => Topic started by: Keith Robertson on 10 November, 2020, 05:21:40 pm
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I have the latest Di2 on one of my road bikes. Recently I had to really get to grips with all the settings, the rear hanger need straightening, so the rear mech also needed tweaking too. What I discovered...
The rear mech being electronic is setup in the opposite way to mechanical. This means you setup the shifting first, then adjust the limit screws. The shifting or trim as its called, can be adjusted using the latest Shimano eTube app. I have this on my iPhone. The advantage of using the app instead of doing it manually is you have a number on-screen to tell you precisely where the trim is set to. Manually you don’t really have an idea apart from guessing.
It’s easy to use, the app guides you, the chain is automatically put onto the 5th sprocket on the cassette and the inner ring on the front. You then have a range of + or - 16 steps either side of ‘0’ in the centre. You are advised to move the derailleur inwards in small steps until the chain is making a noise against the 4th sprocket, then back off towards the centre by 4 steps and it should be fine. All done remotely with buttons on the phone screen.
What I found is when I disconnected the app and went back to normal mode to check the shifting, it would get stuck going towards the smallest sprocket, never the other way, towards the largest. When on the inner ring at the front the chain would find it hard to go from 4 to 5. When on the largest chain ring at the front the same would happen going from 6 to 7. I only really noticed this when riding, it didn’t show up too well in the workshop.
I had to re-trim a few times, moving the trim position a few clicks towards the smallest sprocket. It ended up being at position +7 and now shifts really well.
Limit screws conundrum...
Lower Limit: This is a bit baffling as the Shimano manual tells you to ‘tighten the bolt until it just touches the left link’. No online (YouTube mainly) help here with what is this ‘left link’. I can only guess it’s some kind of cryptic Japanese translation...? What I ended up doing is undoing the screw completely and then tightening until I could see the end touching the relevant part of the rear-mech.
Amusingly, if it’s too tight, the mech wont stay in 1st gear, automatically shifting to 2nd to protect the motor. If it didn't do this it would always be trying to force itself into 1st and drain the battery and possibly wreck the motor.
Similarly with the High limit. I put the chain on the 11th sprocket with the screw completely undone, and then tried to tighten. But this time you can’t see anything directly. When the screw touches ‘the left link’ you back off one complete turn of the hex key so the shifter can over shift then return under the 11th gear.
Thoughts and queries!!
The shifting works very well with both limit screws completely undone and ineffective. The electronics know where they are all the time and can’t over-shft into the spokes or off the end of the cassette.
Adjusting the limit screws doesn’t seem to be done to actually move the rear mech in any way, ie position it in the right place, this is done electronically. They really are just hard limits to travel, so to speak.
So, can the limit screws just be forgotten about, are they there just to reassure traditionally minded people that the electronics haven’t taken over completely, or do they do anything useful?
Could my mechanical bike’s rear mech be setup in the same way? Get the trim / shifting working properly using the cable adjustment, then use the limit screws afterwards just to stop any excess movement, not to fine tune any positioning?
Any thoughts much appreciated!
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I have the latest Di2 on one of my road bikes.....
So, can the limit screws just be forgotten about, are they there just to reassure traditionally minded people that the electronics haven’t taken over completely, or do they do anything useful?.....
it is typical servo arrangement, i.e. the motor is driven until either
a) the feedback signal from the resolving element signals the correct position has been achieved or
b) some other kind of fault condition is triggered.
So having the limit screws set to limit the mech travel too much (so that bottom gear or top gear cannot be cleanly selected) is a good example of b). When the system goes loopy (eg a fault with resolving element) the motor will carry on trying to run unless the limit screws physically stop it and this triggers another type b) event. Without the limit screws set a fault in the resolving element can result in the mech merrily shifting into the spokes.
Q. Do such faults ever occur? A . yes of course they do. I have not been able to watch a professional bike race in recent years without seeing multiple examples of faults of this type occurring; the usual outcome is that the mech can't be shifted out of the one gear; some riders have had the same fault occur more than one day running in a stage race which means the mechanic didn't really fix it even though they probably thought they had. If the limit screws have not been set and a fault of this kind occurs then the mech can do a 'death plunge' into the spokes instead.
cheers
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In my experience Shimano tech docs are excellent, should be followed to the letter, and care taken not to miss small details and steps which may differ from the norm.
Brucey alludes to something which can cause a fault. DI2 overshifts, then returns. If you have limiter screws set in as you would a cabled system, the mech can keep activating and pressing against it, which eventually fucks it.
Here is a decent site for advice:
https://bettershifting.com/installation-guides/
Also, see this:
https://bettershifting.com/micro-adjust-di2-derailleurs-using-computer-no-levers-required/
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Could my mechanical bike’s rear mech be setup in the same way? Get the trim / shifting working properly using the cable adjustment, then use the limit screws afterwards just to stop any excess movement, not to fine tune any positioning?
Mechanical shifting allows the cable to be slack enough in top gear that the mech position is defined by the H limit screw. Similarly the cable pull in the shift to bottom gear is more than is required and the cable is pulled firmly into the L limit screw.
This means that the limit screws are doing slightly different things in the two systems; in a mechanical system they define the mech position in both top and bottom gears. In the Di2 system they are there (I think) primarily as a backstop.
Mechanical shifters allow a certain amount of 'overshift' on downshifts; this in combination with a poorly set L screw can allow the mech to go into the spokes.
cheers
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Mechanical shifting allows the cable to be slack enough in top gear that the mech position is defined by the H limit screw. Similarly the cable pull in the shift to bottom gear is more than is required and the cable is pulled firmly into the L limit screw.
The manual for adjusting the mechanical version (https://si.shimano.com/pdfs/dm/DM-RARD001-02-ENG.pdf) says the H screw should be set so the pulley is level with the "outer line" (I think it means "outer face") of the smallest sprocket, which would mean it wouldn't be touching the screw when in top gear.
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The manual for adjusting the mechanical version (https://si.shimano.com/pdfs/dm/DM-RARD001-02-ENG.pdf) says the H screw should be set so the pulley is level with the "outer line" (I think it means "outer face") of the smallest sprocket, which would mean it wouldn't be touching the screw when in top gear.
if the cable pulls were all uniform, that would be the case. However they are not.
cheers
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Brucey sums up DI2 vs mechanical limit screws perfectly and HF sums up the best way to resolve Shimano problems - don’t ask me how I know the latter, but there’s a thread around here somewhere where I mention discovering adjustable reach and bite for Shimano road hydraulics...
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do you need a special widget to connect to the iphone?
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do you need a special widget to connect to the iphone?
Yes, one of these:
https://bike-discount.de/en/buy/shimano-ew-wu111-di2-wireless-unit-d-fly-ant-bluetooth-885683
J
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do you need a special widget to connect to the iphone?
Yes, as per QG post, but its also important to know that the widget does not work on some older models of battery (ie. about 4 or 5 years old)
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do you need a special widget to connect to the iphone?
Yes, as per QG post, but its also important to know that the widget does not work on some older models of battery (ie. about 4 or 5 years old)
Indeed. And you can't get Syncroshift with the older battery either. I'm just not sure if either feature justifies the expense of an upgrade while I still have life in my current battery...
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In my view it doest. Synchroshift is of no interest to me.
Even the app is of limited use because all it saves you from doing is firing up a laptop, and as long as you dont need to change settings frequently (and why would you) or set the system up frequently, then it seems fairly redundant.
The bluetooth dongle is of use if you want a gear readout on your bike computer, and if you want to use the hidden buttons on the STI levers.
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I have a brand new bike with ultegra Di2 and the bar end charging. i wondered if it was built in to that. If not i agree about the cost benefit inutility.
I thought the hidden buttons on the sti levers was still only on Dura-ace or is itnow on the latest generation 8050?
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I have Dura-Ace. I cant speak for the peasant version.
;D
I doubt you have the bluetooth dongle fitted. But you could download the app and see.
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Synchroshift is of no interest to me.
I like the idea of Synchroshift. Just not enough to spend >£100 on a new battery that I don't otherwise need.
Even the app is of limited use because all it saves you from doing is firing up a laptop, and as long as you dont need to change settings frequently (and why would you) or set the system up frequently, then it seems fairly redundant.
I can't imagine most users ever really need to tinker with the settings. The adjustments you can make seem to me to be mostly aimed at racers who might want a different shifting profile from one race to the next, but even then it's an edge case.
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I have had super compact absolute black chain rings fitted and the shifting is not quite perfect so i need a bit of tweaking. I think the shop whilst excellent were not quite as good with Di2 as cables
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Some light reading for you:
https://si.shimano.com/#/en/DM/R8050
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In my view it doest. Synchroshift is of no interest to me.
Synchoshift is Brilliant!! Love it. I have it on my bike, an it's amazing. I only have one button on each break lever unit, and then two more buttons on the end of the aerobars. Synchroshift makes this work. The simplicity is wonderful. I just press up or down buttons and away we go. Also because they are all buttons and not levers, they are really easy to use with big thick gloves on, or when your hands are tired after a long ride. The bar end buttons are great for this as I can just slap them if I need to.
Even the app is of limited use because all it saves you from doing is firing up a laptop, and as long as you dont need to change settings frequently (and why would you) or set the system up frequently, then it seems fairly redundant.
Assuming you have a laptop to hand. Want to change a setting while away on holiday? didn't bring the laptop?
That said, i haven't used the app (or a laptop for that matter), to fiddle with my di2 since i set it up last summer.
The bluetooth dongle is of use if you want a gear readout on your bike computer, and if you want to use the hidden buttons on the STI levers.
I have my di2 synced to my wahoo, and it's great, not so much for displaying what gear I'm in, I don't need that, I have the MTB Junction a, which does that for me. No, the main reason for it is to log what I used when. Provides plenty of data that you can then mine "Oh look I never use that gear" or "I use this gear a lot..."
I like the Bluetooth whatsit for di2. Makes the thing a lot easier to use.
Di2 is brilliant, so glad I have it.
J
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Yes, I'm sure it is all of use to some people, just not to me 😂
I have two Di2 bikes, one of which is exclusively a winter bike, and IMHO, that is where it comes into its own. The advantages are moot on my summer machine, but in winter it is amazing....no cable outer/inners to get clogged up and degrade shifting. Maintenance free, bar the occasional charge (...and only one battery to monitor and charge, Etap dickheads 🤭)
Best of all, its piss easy to shift when have cold tired hands or are wearing thick gloves. my fingerjust sits between the two buttons and the tiniest movement is all you need.
Never listen to ignorant claims that it doesn't work with winter gloves 😉
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Want to change a setting while away on holiday?
Yeah, my last holiday was ruined because I couldn’t tweak the shifting profiles on my di2. Ruined, I tell you.
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I'd have turned back at the airport, personally
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Yeah, my last holiday was ruined because I couldn’t tweak the shifting profiles on my di2. Ruined, I tell you.
You're on Holiday and have a mechanical that damages your cassette. You next day a new one, and a chain from wiggle, but they didn't have the same size in stock, so now your 11-40 is an 11-36, so you want to change the way the system handles it...
You had been doing lots of flat TT stuff, so had the 11-28 on there, as you're packing your bike to fly out to some Spanish island, you swap it for an 11-40. Get to your destination and realise you forgot to change it in the system...
You're riding a long and get side swiped by an ignorant Belgian driver, you fall over, the bike is all fine, apart from damage to the left hand shifter. You use the app to reconfigure the right shifter to do synchro for you...
But sure, you've never had any of these happen, so it can never happen to anyone...
Yes, I'm sure it is all of use to some people, just not to me 😂
I have two Di2 bikes, one of which is exclusively a winter bike, and IMHO, that is where it comes into its own. The advantages are moot on my summer machine, but in winter it is amazing....no cable outer/inners to get clogged up and degrade shifting. Maintenance free, bar the occasional charge (...and only one battery to monitor and charge, Etap dickheads 🤭)
Best of all, its piss easy to shift when have cold tired hands or are wearing thick gloves. my fingerjust sits between the two buttons and the tiniest movement is all you need.
Never listen to ignorant claims that it doesn't work with winter gloves 😉
I didn't say it didn't work, I said it was really use to operate with big thick winter gloves on. More over if your fingers are a bit cold, you don't need any dexterity to slap the button...
Agreed on the low maintenance. I like that I can take the rear mech off, clean it, and put it back on, and there's no adjustment needed. it just works.
J
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I didnt say you said it didnt work with gloves....jeez...chill fuksake ;D
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In my view it doest. Synchroshift is of no interest to me.
You're underrating it. I literally never touch the left shifter, or care whether I'm in the big ring or the little ring. There's just a simple straight run of gears.
Even the app is of limited use because all it saves you from doing is firing up a laptop, and as long as you dont need to change settings frequently (and why would you) or set the system up frequently, then it seems fairly redundant.
That presupposes everyone owns a Windows laptop. For many demographics, that's like assuming they own a working VHS machine or a trouser press.
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True, but, as ever, I was speaking about the utility of the app from my perspective. I tend never to gainsay the actual experience of others (unless its mattc)
As for synchro, again, I can't see a use for me, as I don't find the conventional operation problematic. Admittedly, I've never bothered trying it 😏
It'll have to wait until summer though. My winter di2 is 5 years old and wont do it
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But sure, you've never had any of these happen, so it can never happen to anyone...
Yeah, it’s easy to invent scenarios where it might be useful.
I’m more concerned with what’s likely in real life. My real life, rather than anyone else’s.
It’s not something I consider likely to ever be useful enough *to me* to be worth shelling out £100 for a new battery. YMMV.
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As for synchro, again, I can't see a use for me, as I don't find the conventional operation problematic.
I’m basically an idiot and find operating two separate mechanisms quite taxing on the brain. Especially as they work in opposite directions. I would genuinely find Synchroshift useful.
It’s a bit like having the Garmin beep at me to tell me when to go round a corner - just one less thing to think about. Leaves me to spend more time enjoying the scenery.
I’m actually talking myself into upgrading the battery here.
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£94 from Decathlon ;)
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Some thoughts from the more plebeian 8070 level(?)
- ultegra does have hidden shifter buttons
- the bar end/in frame charge port and button says Bluetooth enabled, BUT you still have to give someone 130 to get the aerial (or inline Bluetooth module)
- I have synchro shift set up. It doesn’t stop you using the shifters normally, but you can set it to stop you downshifting to big-big when the chain is a link too short. That’s 😌
- HF is right - perfect for winter as no cables to get draggy with dirt. Really needs to be disc brakes for this. No guards on that bike though...
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Oh, and I agree with HF - I think i still prefer cables for nice weather when the stuff just works with fine mechanical precision.
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Thanks for all the useful replies everyone :thumbsup:
This site https://bettershifting.com/installation-guides/ was the best one I’ve seen so far for detail.
For what it’s worth, I find myself using the synchro shift all of the time (on 2 out of three bikes, third one is still mechanical) all very simple. Don’t forget - you can still use the left shifter to shift the front ring if you want to ;)
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Di2 on winter bikes, you posh b'stards. Well jells innit.
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Di2 on winter bikes, you posh b'stards. Well jells innit.
What's a winter bike?
My only change in winter is that I may fit the studded tyres. The rest of the bike is the same bike... It's only weather afterall...
J
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Di2 on winter bikes, you posh b'stards. Well jells innit.
What's a winter bike?
My only change in winter is that I may fit the studded tyres. The rest of the bike is the same bike... It's only weather afterall...
J
I've previously had dedicated winter bikes as I'm so lazy with maintenance, but now I get out far less I'm taking the same approach as you (plus it would mean going from hydraulic discs to rim brakes!), just got to remember to rinse the salt off each ride instead of instantly retreating towards the warmth!
Sent from my SM-G930F using Tapatalk
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What's a winter bike?
An excuse for N+1 for those with the disposable income and suitable storage space.
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I've previously had dedicated winter bikes as I'm so lazy with maintenance, but now I get out far less I'm taking the same approach as you (plus it would mean going from hydraulic discs to rim brakes!), just got to remember to rinse the salt off each ride instead of instantly retreating towards the warmth!
I have one of those garden sprayer things, the ones where you pump it up with a handle, and it has a sprayer on a hose. Originally intended for spraying weedkiller and the like. I have one of these with clean water in it, so I can easily rinse the bike without needing to faff with anything like hoses. It really makes a difference.
J
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I have one of those garden sprayer things, the ones where you pump it up with a handle, and it has a sprayer on a hose. Originally intended for spraying weedkiller and the like. I have one of these with clean water in it, so I can easily rinse the bike without needing to faff with anything like hoses. It really makes a difference.
I have one of those too. Works equally well on the dog after a muddy walk in the woods before letting him back in the house, though he's not a big fan. The bike puts up less resistance.