Part I: Exploring options
So i’ve been toying with the idea of ‘fixing’ something that isn’t necessarily broken: the chain tensioner on my bicycle. i had a double-wheel tensioner (OEM Rohloff), and it worked fine. For all of my purposes, the chain never skipped or fell off, and emergency wheel-releases and tyre-changes were predictably possible-but-not-fun. For this last bit, i run a Rohloff retro-fit, so tire changes generally require a bit more hassle than conventional derailleur setups.
The idea of changing the tensioner has two basic notions: 1) the push-up position provides more positive wrap on the rear cog, which is a good thing; 2) it could make it easier to remove the rear wheel for maintenance—in part because it would be possible to dentension the lever and take the chain off for even more chain slack, and the tensioner jockey-wheel seems to be further away from the dropouts and thus not in the way when dropping the rear wheel out.
There are three general types of tensioners, as far as i have found:
1. The spring-tensioned tensioner, e.g., Surley Singleater. It attaches via the RD hanger, and has a small spring that can adjust to either pull down (conventional tensioner position) or push up. Some users claim the spring tension in the push mode is too weak or fails over time, but also report that chain-line adjustability is very easy. A lot SS/fixie skinny-jean indy kids seem to like these, but then again they rarely ride anywhere but urban and relatively flat situations; whereas i’d like something that can take the bruising of IGH touring.
2. Fixed spring-less RD hanger tensioners, e.g., Soulcraft Convert. It also attaches via the RD hanger, but tightens manually through a friction bolt on the hanger. A few users complain that the bolt grip isn’t strong enough to maintain the tensioner’s tension (edit: as i’ve discovered this is untrue); advantages are very limited chain bounce (no spring means no recoil), and stronger push since it does not rely on any kind of spring. The use of a roller instead of a wheel (in the case of the Convert) also raises some eyebrows, but i haven’t found any complaints of this in real-world-use reviews (just theorists complaining in advance).
3. Fixed spring-less drop-out tensioners, e.g., Rennen Rollenlager. These attach at the dropout axle and pivot at the RD hanger. These seem to offer very reliable “push,” but there has been some concern about the RD hanger adjustability and fit, not to mention attaching it via the RD hanger and the axle makes removing the rear wheel much more difficult than the OEM Rohloff tensioner—so not a very good candidate for my use.
Part II: Installation
After some thought i decided to try out the Soulcraft Convert tensioner in “push” mode. As i mentioned before, some of the reasons for wanting a push tensioner are 1) ease of rear wheel removal (in the specific case of the Convert); 2) slightly simplified chain run; 3) greater positive contact on the rear cog; and 4) in my opinion it looks nice (admittedly, not a very valid reason).
The Convert has an especially nice feature in that there is a built-in release, so that it is not necessary to loosen the hanger bolt to detension the chain and access the rear wheel; one need only press the release button and the whole arm simply swivels away (by way of a simple spring-activated peg on the inside of the main bushing). In a word: easy-peasy.
Some minor notes:
1) installation requires removing all paint from the RD hanger bolt area; if you can’t bear to do this to your bike, then it won’t work (it’s a friction bolt, and so it will likely slip on painted surfaces);
2) for all of Soulcraft’s tongue-and-cheek commandments, the instructions for how to adjust the Convert to the chainline—Seventh Commandment, Fig. 8—could be clearer (at least for tools like me who are used to hanger-based spacers like the Rohloff; i guess everyone needs at least one thing to complain about)———adjustments occur at the roller (not the hanger) by way of a 4mm hex wrench and adding or removing M7 washers (six of which are included, along with an M7 plastic spacer about 6.5mm wide); achieving the Rohloff’s 54mm chainline is a breeze, as though the Convert were made to be its consort;
3) there is more slack using the Convert’s “push” setup than with a conventional double-jockey (sprung) tensioner—this is normal and doesn’t impact use—Soulcraft also reminds users to this effect;
4) the Convert is still more expensive than Rohloff’s tensioner (which is itself expensive) yet does more or less the same thing. On the other hand—and it’s an upper hand in my opinion—the Convert does offer more rear-cog wrap and an even cleaner, out-of-the-way chain run. As for weight weenies, i think the CNC’d Convert weighs close to the same as the OEM Rohloff tensioner; i.e., i don’t own a scale that can accurately gauge the slight differences in weight as undetected by my hands.
5) in my case, chain length would be better if i had a 3/32 halflink; as it is, it works, but it’s less perfect than it could be, although actual efficiency is just the same;
6) finally, and perhaps most importantly, removing the rear wheel is a total breeze with the Convert; this aspect alone makes it superior to conventional tensioners and makes it worth every penny more than the Rohloff tensioner.
Part III: First Impressions
After installing the Convert, i took the bike out on a short ride (actually, my daughter and i joined a local parade as part of the bicycle section!): A few short hills (nothing long, and nothing steeper than about 8%), towing about 100lbs in weight for about 12miles. The ride had a lot of stop and go, so a lot situations with uneven tension on the drivetrain. Later, i also went on a short 20-mile ride with some long ascents and descents without any towed weight.
First off, now that the chainline is dialed in there is absolutely no noise from the roller (in comparison to a regular double-jockey tensioner). In fact, it actually seems a little quieter. Each pedal stroke is also smoother, although i did have the Rohloff tensioner operating at maximum tension, so this difference might not be felt by other users; for me the Convert is noticeably smoother.
During my first ride, climbing while towing weight made absolutely no difference; the Convert maintained tension throughout. Coasting down hills (when the chain is at its slackest, and potentially bouncing) also made no difference. My second ride also went off without any problems. Mischief managed, i’d say—performance was reliably flawless.
I haven’t tired it on bumpier National Forest fire roads—which i will do in the coming weeks. However, i’m not too worried about bumpy roads, because a lot of Convert users are MTBikers who go on much rougher roads than i will ever take.
I’ve posted some photos of the installation here:
 |
 |
 |
