Saturday, 14 December 2013

I Know What I Like, and I Like What I Know

[Long Post Alert]

As alluded to previously, things have not been Quite Perfect with the drivetrain of my new road bike. So this past weekend, we took a closer look at the gear changing and formulated a plan of what things to try (and in what order) to try and improve it... and I learned a valuable lesson. 

Sometimes the latest kit isn't always better. 
Sometimes it's best to stick with what you know. 
Especially when it works. 

In fairness, I did set out on this Build My Dream Bike journey with the right instincts. My priority was to get absolutely the right frame and to spare no expense on the fork and headset. Everything else, I figured, could be sorted out later. And that is indeed true. 

Unfortunately, after barely more than a month, I have had to admit to making a few mistakes on the drivetrain (gearing) setup. I seem to have got a little distracted and thought "yeah, whatever..." on a few things, letting my trust and confidence in people advising me (which was not misplaced, I do assure you) quell any promptings from my inner Princess (you know, the one with the Pea Problem). I simply didn't pay enough attention to join up the dots of what people were telling me with what I knew from my own experience.

I'll start this tale with the original briefing I gave the Enigma team for the groupset:
  • 160mm length cranks -- that's the size the Grumpy Knees seem to do best with.
  • Triple crankset -- I wanted at least as low a gear as the lowest on my steel roadbike (34x36) but also wanted a higher big gear, as I'd been spinning out far too quickly on 50x12. A compact double wouldn't give me that big of a range and as my "lifetime lifestyle" ambitions include some touring, a triple seemed sensible. 
  • Shimano 10-speed cassette -- to achieve the biggest gear range that was still sensible, I wanted a upper cog of 11t and a lower of 36t.   
  • Shimano shifters -- I know and love Tiagra but was hoping to upgrade, perhaps to Ultegra if not too expensive. 
  • Shimano front derailleur -- again, I know and trust Tiagra but would upgrade subject to price. 
  • Shimano rear derailleur -- I've had the Deore 9-speed on my steel roadbike and it works beautiful, so, provided it would work just as well with a 10-speed cassette, this would my first choice again. 
Paul at Enigma was totally sympathetic with my priorities and choices. He's finicky about performance but also values comfort and enjoyment, so we were completely in harmony in what we wanted to achieve with the selection of components.

So we went through my wish list and came up with the plan for a hybrid drivetrain:
  • Specialites TA Carmina cranks in 160mm 
  • Specialites TA triple crankset (52/39/30)
  • Shimano CS-HG62 10-speed cassette (11-36)
  • Shimano 105 shifters 
  • Shimano 105 front derailleur 
  • Shimano Deore rear derailleur 
As you can see, this pretty much matched the briefing, with the Shimano upgrade being up one level from Tiagra to 105 rather than Ultegra. The significant feature of this system, though, is that it's a "hybrid": half Shimano and half Specialites TA. However, it was reassuring and helpful in a practical sense to know that Paul himself runs hybrid-brand (Specialites TA x Campagnolo) drivechains on his own bikes and has built up variations of these for customers. He understands what potential compromises are involved when you choose to customise your gear ratios (by choosing each chainring). But not only does he know that the build, if done correctly, will work but he has ridden these systems himself for hundreds (if not thousands) of miles.

But then two things happened with this plan: Enigma found they couldn't obtain two of the items on my build list, so we had to come up with alternatives. This situation came about because the list of suppliers available to Enigma was somewhat limited: as industry 'insiders', they buy wholesale from distributors such as Madison, Ison, Extra. They don't buy from online retailers like Wiggle or Chain Reaction Cycles, which sell a lot of the same items but at retail prices. 

The items that got problematic were: 

The Crankset

Enigma's Specialites TA source is Chicken Cycles. I'd run across Chicken Cycles myself when searching online for shorter length cranks, and their name came up again in discussions with Cyclefit. If for some reason you didn't want Thorn or Miche cranks (which I didn't, mostly for aesthetic reasons), then Specialites TA were the remaining viable option. But it's by no means a case of being the 'losing' option by a process of elimination: Specialites TA is a venerable French brand producing top quality components, and their cranksets are arguably some of the prettiest out there -- nearly as pretty as Campagnolo but the added attraction of being that bit more uncommon. (In the US, Velo Orange would also be a very attractive option.) 

Anyway, if you're in the UK and you want Specialites TA, Chicken Cycles is the main source. They've been a Specialites TA distributor for a very long time and normally carry an enormous range. However, they seem to have a problem with their reputation: Julian at Cyclefit looked at their website with me, agreed the Carmina cranks in 160 looked perfect, then sort of ummed and ahhed before saying "well, they might not have them in stock... and who knows when they'd get around to shipping them..." And then Paul said much the same! [And a check of their website today indeed does suggest that "sure, you can order these from us but you'd better not count on getting them any time soon... and by the way, we have no idea how much they'll cost you when we do get around to shipping them.... if we get around to shipping them..."]

But as a fall-back, Paul has contacts from one of his previous lives running the CTC Shop, so he thought it was worth having a go. We went for the longest possible lead-time we could, with Paul placing the order with Chicken literally the day after I confirmed the order on my new bike.

The Rear Derailleur

We didn't know until nearly the last minute that, apparently, Shimano has discontinued making the particular rear mech that I wanted, my tried and true Deore 9 speed. 

The day before the bike was due to be built, Paul e-mailed me to say that they'd not been able to find the Deore rear derailleur in stock with any of their suppliers. He told me it hadn't occurred to him to check when I ordered it, as he "assumed that mech would be available forever!" Not to worry, "We've upgraded you free of charge to a 9 speed XT" [which was still difficult to source as 9-speeds are going out of fashion in favour of their 10- and now 11-speed successors]. However, Paul felt this 9-speed XT mech would "work better with a 10-speed STI than a 10 speed MTB mech [i.e. better than whatever the Deore's successor is now], since the XT mech has a reverse spring which, as we are pushing the capacity [with 11-36t], should help as the spring helps [the mech] get the spring get up to the largest sprocket. The levers work opposite to the norm but it's easy to get used to".

(I took "levers work opposite to the norm" at face value but as it happens, Paul was right and I didn't find this a problem at all. But if you're interested in how this works, I've found a bit more information in various cycling forums, which explains that the model Paul chose (the SGS Rapid Rise) is (a) long cage, and (b) "low normal" which means that spring tension pulls the mech to the larger cog, whereas cable tension pulls to the smaller cog. This is the opposite of "top normal" which is the standard mech setup, where spring tension pulls the mech to the smaller cog (higher gear) and cable tension pulls it back (to a lower gear). The result is that, with low normal, if your gear cable breaks, there is no cable tension so you're stuck on the largest cog, i.e. the lowest gear. Which is not a bad place to be in that situation! The other difference is that "top normal" allows you to 'drop' several gears downwards (to lower gears) at a time, great when you turn a corner and find yourself confronted with a wall to climb. "Low normal" on the other hand lets you 'grab' 3-4 gears upwards at a time, i.e. if you want to spring. Personally, I'd love to be able to drop gears in a hurry, but, well, you can't have everything.)

In any case, I thought the 'upgrade' to the XT mech sounded like a good idea, maybe even better than the Deore I had asked for. And wouldn't it be smarter anyway to go with something we knew was currently available -- and therefore replaceable if need be? 

What I was forgetting was that I have damaged the Deore rear mech on my steel road bike twice this year. After each accident (all of two weeks apart), I purchased a brand new replacement from Chain Reaction Cycles. So I had in fact purchased two Deore rear mechs in September 2013 alone and, if my brain had been joining up the dots, I knew full well that they were still available from retailers. But I didn't make the connection when Paul told me he couldn't get one (from a wholesaler). As they say, context is all. 

The Build

Weeks went by -- as they do -- and in early October I began discussions with Enigma about the expected build time. I posted off a box of my own stuff that would go on the bike. Paul began working through the components list, checking that everything ordered had been received, including the Shimano XT rear derailleur as we'd agreed. 

Meanwhile, however, nothing had come in from Chicken Cycles, so Paul phoned them up. They didn't think they had the 30t inner chainring -- they'd have a look around their warehouse. Oh, and they definitely didn't have the Carmina cranks. Hmmm, nice of them to tell us... more than two months after they had received the order. 

We heard nothing further for a few days, while Paul and I discussed options. I agreed I'd take Vega crankarms (black rather than the silver that Carmina comes in) but I really did want that 30t inner ring! Paul contacted Chicken again. They said they might have a 28t inner ring... Paul knew my priority was as low a gear as possible so he told them "Fine, as long as we have a complete working chainset at the end of the day. Put it all together and send it over."  

What Chicken sent:  Vega cranks in the correct size, with the correct spider, plus three chainrings in sizes 52, 39 and... 28. 

Paul confirmed to me when he'd received all these and said we were good to go. As soon as Jaco finished the frame, everything would pass to Greg to do the build, which should take about one day to do. That day looked to be Friday, so we agreed I'd go down to be fitted and to collect the complete bike on Saturday. 

As you'll know from previous posts, that build did happen.... and I got my new bike right on schedule. At my visit to Enigma to collect it, though, Greg, Paul and I had a long chat: "Hybrid" drivetrains are not designed to work as a cohesive unit and are, at best, idiosyncratic! Mine pushes all the currently acceptable limits, so I should expect some teething problems while I learned how to work with it. For example, the Shimano XT rear mech would not be the smoothest, quietest apparatus when handling a 10-speed cassette with cogs ranging from 11 teeth to 36 teeth! Likewise, the Shimano 105 front mech was not entirely happy dealing with a 24 teeth difference between the 28t inner ring and 52t outer ring. (The recommended limit is a 22t difference.) They warned me to be strict with my chain lines and shifting patterns and that the most likely problem would be shifting from the inner chainring to the middle one. I told them a little about my background as a Citroen A-series (2CV, Dyane, Ami) driver and the experiences I had while learning to double de-clutch. They visibly sagged with relief! At least they now knew that I had some understanding of quirky machinery and some experience with learning how best to coax them into behaving... and I now had some idea what I was letting myself in for! 

The XT rear mech with monster cassette --

The Specialites TA triple chainrings with Vega cranks --

The Reality 

Judders & Slips

On the day I collected my bike, my route home from the train station took my up one of the toughest hills I have (to date) encountered. The approach to the bottom is from a left hand turn, so there's little scope for getting a run at it -- you take the corner as fast as you can (which is not very fast) and then try to hold off each down shift as long as you can. But down shift I do, in quick succession. In fairly short order, I went from big ring to middle and then to inner (granny) ring. Almost immediately, I became aware of the drivetrain being quite noisy. But then I expected this. But it seemed to be an uneven noise, a syncopated kind of ker-chunk...ker-chunk...ker-chunk. Halfway up the hill, I asked Adam to drop behind me and have a look at the rear mech. He said that the jockey cage seemed to jump up and down quite a lot more than he'd have expected. On the lowest couple of gears (cogs 1 and 2), I certainly had all the pedalling ease I could want from impressively low gears, and the system felt secure, i.e. not slippy on the cog, but the uneven noise was a bit disconcerting. 

I carried on and figured I'd have to refine my technique to reduce -- and hopefully eliminate -- that judder. 

Weeks went by... and the judder continued. This was happening on the lower (bigger) third of the cassette and also a bit on the upper (smaller) 2-3 cogs. There was, moreover, a separate, more worrying problem:  when shifting down through the cassette (from smaller to larger cogs), the chain did not want to stay on cog 4 but would slip straight to cog 3.

"Double De-Clutching"

Paul and Greg were quite right about the workings of the front mech. There is no problem shifting between the middle and outer rings, and all goes well shifting from middle to inner. But bringing the chain back up from the inner to the middle is definitely a struggle. Once or twice, I've had a smooth shift. But in most cases, a full shift of the lever produces slight overshift, almost 1-1/2, with the chain slightly overshooting the middle ring.

I can deal with this in one of two ways: a second quick shift up to the outer ring and then a full shift back to the middle; or a light down tap of the lever which usually results in a half-shift down back squarely to the middle ring. If I go for the first option, there's a lot of scary noise, including shocked intakes of breath by my riding companions. If I go for the second option, I think of it as akin to 'trimming' with friction shifters. Either method works, but I find the inner>middle>outer>middle sequence a little more reliable, if a little longer to achieve. 

Pragmatically, I find the system does work -- even if it sounds like a mini warzone around my crankset -- and I have a fantastic range of gears over the 52/39/28 rings.

But obviously I would much prefer to have quiet, smooth, precise shifting between all three rings.

What To Do? 

The Rear Mech

1. Could the mech hanger simply be too short? 

Our thinking here was that perhaps the entire mech, including jockey cage, sat too close to the cassette, with clearances too small to cope with the bumps and jolts of normal road cycling without hitting the cassette. Adam had noted that the mech hanger was significantly shorter than the ones on both his Planet X and Pinnacle road bikes, both of which have much smaller-diameter cassettes.

I phoned up Paul and asked. While it seemed to be a possible explanation, replacing the mech hanger with a longer one wasn't an option, as it has to fit the drop out. These drop outs (disc ready and with rack mounts) are a pretty unique bit of kit, machined in the US by an engineering firm called Paragon, which also designs a specific mech hanger to go with it. In fact, Paul indicated that the righthand-side drop out and mech hanger were received already bolted together. There simply would not be another mech hanger anywhere on the market of the exact specification to fit the Paragon dropout.

Oh, if only all these things were standardised...!

2. Rotate the angle at which the rear mech is attached to the mech hanger?

Forced to work with the hanger that we had, Adam thought perhaps it might help to loosen the mech off from the hanger, rotate it slightly then tighten back up. The idea is that the mech being fixed at a different angle might reduce or eliminate the judder we could see, feel and hear, and possibly even put an end to the slippage between cogs 3 and 4.

I don't think words can adequately describe what he meant, or show what the desired effect would be, so I've fashioned a primitive diagram from a photo:

The red curved line shows the chain line resulting from the fairly straight up-and-down alignment of the XT mech. This alignment produces a tight angle as the chain circles the jockey wheel (located behind the mech). What happens here is that these angles pull the jockey wheel up so that the chain running along its top actually strikes the cassette cog above.

Adam proposed rotating the mech at its fixing point to the hanger (where the tops of the straight red and blue lines meet). The idea was that the mech would be positioned slightly lower down and to the left -- with the new chain line represented by the curved blue line. The angle of the chain line through the jockey wheel would be opened up (with the chain in fact being in direct contact with the jockey wheel for a slightly shorter distance). You can see the degree of drop. The hope was that there would be a bigger gap between the top of the chain as it circles round the jockey wheel and the cassette cogs above it, so that, with any jolts in motion, there would be less chance of contact. Whether the jockey cage itself would be more stable, with less jumping around and less noise, we couldn't really predict.

So we tried this. On the workstand, the entire chainline did seem a little smoother and quieter, but when I took it on a test ride, I found no change at all -- still juddery, still KER-CHINK....KER-CHINK, and still unable to keep the chain from slipping off cog 4 to cog 3. 

3. Jettison the XT mech altogether and fit the Deore that I'd wanted in the first place? 

Frankly, this is what  I thought it would come to in the end, anyway. So I had ordered in another Deore mech from Chain Reaction Cycles, where I'd had no difficulty getting them before for the Pacer a few months ago.

So we removed the XT and fitted the Deore. (Well, Adam did -- I took photographs!)

Adam's method is to partially disassemble the jockey cage,
as an alternative to breaking the chain. 

The XT Mech now detached.

Quick comparison of the XT and Deore out of curiosity:
the jockey cages are the same length. So if there's anything about
the Deore that gives more clearance from the cassette
or just generally runs more smoothly, it's not that. 

Feeding the chain through the centre of the cage.

Re-fastening the two halves of the cage, to enclose the chain so that it
feeds around the two jockey wheels.

The chain now suitably caged.

Fixing the mech to the drop out.


With the Deore mech fitted, I set off on another hilly circular test ride with carefully low expectations. My short loop has a swoopy descent and then a short steep hill. I got to shift up quickly through almost all the gears and then a few seconds later shift through them all again, this time downwards, to climb the hill. This was a really effective test of the entire system in just a few minutes.

I was quite surprised then -- and very pleased -- to find that every single shift through the caseete was smooth and precise. Interestingly, shifting upwards (from larger to smaller cog) produced a metallic click, which never happened with the XT mech but was always present on the Pacer (with its succession of three Deore mechs). I've always called it a clang, but it's not loud and I've grown to find it companionable in its own way.

So with the full cassette now at my disposal, I am what they call "a happy bunny".

But what about the chainset, with that double de-clutch coddling?

Well, Chicken Cycles can -- as far as I care -- just rot, since I had no trouble whatsoever sourcing exactly the correct 30t inner ring... online from Wiggle!  However, the cranks appear to require a crank extractor with a slightly different interface from the one we have (which we couldn't find readily to hand on Sunday anyway), so the job of swapping out the troublesome 28t for the new 30t ring will have to wait for another day. 

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