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Nexus is a family of parts, of which the Nexus Inter 8 eight speed hub is one. The Alfine 8-speed hub is a very similar, higher-end model which has a disc-brake fitting.
The overall range of the Shimano 8-speed hubs is 307%, and the steps in gears are a bit uneven:Ratio0.5270.6440.7480.8511.0001.2231.4191.615Step22.3%16.0%13.9%17.5%22.3%16.0%13.9%For comparison, the Nexus 7-speed hub as a range of 244%, and the gear steps are more even:Ratio0.6320.7410.8430.9891.1451.3351.545Step17.3%13.8%17.3%15.8%16.6%15.8%Does a hub need repair? A 'clunk' now and again on a Shimano 8 speed hub is normal. It is the sun gear rotating and engaging the axle pawls. Even if you pedal lightly it will make that noise/feeling but not as loud. The harder you pedal during shifting or right after, the louder the noise. It can change as the hub gets older.
Full cleaning and lubing usually restores like-new function but is expected that there will be slight differences in the noise over time.Sometimes the shift spring on the axle can get weak or the axle sleeve that lifts the pawls can get sticky as it wears. I have solved the problem by replacing the axle unit or rebuilding it.Care should be taken to release force on the pedals when shifting. Applying power to a pawl which is partly engaged can damage the pawl. Shock loads have also broken other parts of the axle assembly. He also recommends not standing to pedal on hills.
Instead, shift down and spin.Probably the most common failure, though, is due to insufficient lubrication, leading to contamination by water and dirt. (Links to instructions may be found at the end of this section)The Nexus 8-speed hubs have a overlocknut spacing ranging of 132 to 135 mm, as sold: see. It is possible to reduce the spacing of the Nexus Rollerbrake/freewheeling models to as little as 126 mm by leaving off the Rollerbrake and using a narrower locknut. See for instructions. This is not possible with the or models Including the Alfine.The internal mechanism of these hubs is complicated, and the usual repair is to replace the mechanism in its entirety.
Shimano indicates little compatibility with hub shells of different models - see the last two pages of - but the internal mechanism can usually be replaced with a newer version as long as the hub is in the same series (with or without coaster brake; same number of roller clutches - also be aware of other differences which may affect the design of the shell). See for description of some internal differences. You'll find details about interchangeability if you keep reading this page.Shimano sells the axle assembly only as a unit and does not provide rebuilding instructions for it - but you might disassemble it either by mistake or to cannibalize parts. Are available on the Web site of Aaron's Bicycle Repair.The right-hand hub bearing cup is vulnerable to damage from water contamination. Factory lubrication is inadequate, and is advisable - even with a new hub - also, to make later cleaning and rebuilding easier.The right-hand bearing cup is listed as a replaceable part in some parts lists.
The old one would have to be extracted from the shell and a new one pressed in. If you succeed with this, please send advice, because that repair can save a wheel!Do not lubricate the (cable attachment parts): see.Basic models have a ratchet and pawls at the left side of the internal mechanism, and a roller clutch in the middle. Premium models have two or three roller clutches rather than only the one. These make only a very minor improvement in efficiency but are quieter than pawls and ratchets, and engage more quickly when resuming pedaling or changing gears.
Coaster-brake models have at most one roller clutch.A red band on the shell identifies a Nexus hub with needle-bearing pinions, for higher efficiency. The lower efficiency of 4th gear compared with the direct-drive 5th gear is noticeable on Nexus 8-speeds with plain-bearing pinions.
Needle-bearing and plain-bearing pinions can be identified by their different appearance even in a fully-assembled gear-carrier unit.The SG-8R20, SG-8R22 and SG-8R31 have plain bearings; the SG-8R25, SG-8R27 and SG-8R45, needle bearings. Among models with a roller clutch at the left side, the SG-8R30, SG-8R31, SG-8R35 and SG-C6000 have plain bearings; the SG-8R36, SG-8R55, SG-8R56, SG-C6010 and SG-C6060, needle bearings. All Alfine hubs has roller-bearing pinionsA drag spring raises additional issues, and is even used in some models without coaster brakes, to improve engagement of roller clutches. Reader Bruce Dance indicates.
The Alfine SG-S500-based models (hubs and wheelsets) have an 'A' and a 'B' version. The 'A' versions are 'two-roller' internals, i.e. They use a pawl drive on the right-hand side (in 1-4) and the main (body center) roller clutch is preloaded by a drag spring that is set into the hub shell (as also found found in most of the coaster brake versions as well as Nexus hubs with pawl drive e.g., SG-8R25, SG-8R27).(The image at the left shows the drag spring as it slips into the hub shell. The part number for the drag spring is the same for the Alfine as for some coaster brake hubs).A difference in the SG-S500-A hubs (and some Nexus models) is that the roller retainer is castellated (has points which protrude to the left to engage the drag spring) whereas the Nexus SG-8R25, SG-8R27 (Rollerbrake/brakeless also, later coaster-brake and Alfine) hubs have no castellations on the roller retainer.
Instead, there are protrusions on the carrier unit. The castellations, when present, are easily damaged.formerly on the Paul Lange site (now in the Internet Archive) helpfully indicates compatibility with some Nexus 8 hub variants.There is considerable compatibility between shells and internals provided the number of roller clutches is the same. However whilst you can usually fit a tension-spring preload clutch internal into one that was originally fitted with a drag spring, you do need to remove the drag spring. If you try to fit a drag-spring preload clutch internal into a hub shell that wasn't originally fitted with one, there usually is no place to fit the drag spring, and the centre clutch won't work reliably, perhaps at all.While the axle assemblies are mostly identical, a section of the left end of the Alfine axle shown, as well as others, is fatter to withstand the bending moment from the optional disc brake, as shown in the image at the right (courtesy Aaron's Bike Repair). The Alfine left bearing cone threads onto the wider part of the axle. The Alfine requires a wider overlocknut distance than the Nexus without Rollerbrake. There are several different left-bearing-cone part numbers.
Mix and match at your own risk.The Rollerbrake and coaster brake are weatherproof, but drag slightly when not engaged, so if efficiency is a concern, avoid them. They also overheat when used on long downhill runs. We don't know for sure whether any coaster-brake model has needle-bearing pinions, but it appears not.For all Nexus and Alfine 8-speed hubs except the S7000 series Alfine hubs, the cable is loosest in the lowest gear. The S7000 series is the opposite, and the cassette joint and axle assemblies are significantly different.Bruce Dance sends the following warning. It is very easy for parts (pawls or balls) to come adrift during assembly. For example commonly a ball (or balls) can come adrift from the ring bearing, either during assembly, or even in service (if the bearing adjustment slackens). This very often results in destruction of the hub internal, especially in the single or dual-roller hubs with a pawl-drive in the RHS, because the balls can easily get into where the pawls sit and then break them.I therefore advise anyone working on these hubs to assemble the internal into the hub shell without the sprocket and the dust cover, and to be sure that all the balls are still present, and that the cone adjustment is pretty much done before the covers are refitted.
Similarly if the hub has a pawl drive on the LHS (for gear 1 and 5), the internal ought to be rotated backwards as it is installed, else pawls may be dislodged.I have seen one hub in which a roller came adrift (presumably during the factory assembly, since they cannot easily come out in service) and this smashed the hub shell to pieces. Kind of ugly.Shimano has information on most but not all 8-speed models. These hubs have gone through several minor design changes, resulting in new model numbers and parts incompatibilities. Hubs parts numbers start with SG but there are also other parts listed, including brakes and shift levers. Alfine 8-speed (Disc brake/no brake) models ModelFeaturesDocumentationMU/Cassette JointInterchangeabilitySG-S7051-8Electrical (Di2) shifting.
Mostly compatible with SG-7001-8 but axle assembly and right-hand cone assembly are different.MU-S705SG-S7001-8Uses CJ-7000 cassette joint with cable entry above axle.CJ-S7000SG-S7000-8 andSM-S7000Mostly compatible with S501 but axle assembly and cassette joint are different.CJ-S7000SG-S505Electrical (Di2) shifting. Most parts compatible with S501.MU-S705(11-speed)SG-S501Three roller clutches, fully-compatible with S500.CJ-8S20SG-S500Two roller clutches (A type); three (B type).
The A type has a drag spring and castellated roller-clutch assembly. See.)CJ-8S20A type:B type:,WH-S501-8D8-Speed rear wheel; three roller clutchesCJ-8S20(A type, B type), (B type)WH-S501-V-8D8-Speed rear wheel; three roller clutchesCJ-8S20(A type, B type),WH-S500-8D8-Speed rear wheel; two (A type) or three (B type) roller clutches. The A type has a drag spring and castellated roller-clutch assembly. See.)A type: seeCJ-8S20(A type, B type),WH-S500-V-8D8-Speed rear wheel; two (A type) or three (B type) roller clutches. The A type has a drag spring and castellated roller-clutch assembly. Ideally, the frame should have a dropout of 127 to 135 mm to fit one of the Nexus hubs. Older bicycles are typically narrower than that.
In the case of frames, it is usually possible to spread the rear triangle to the needed width. Any good bicycle mechanic will be able to do this, or Alfine hubs require 135mm spacing.If you leave off the Rollerbrake ®, you can get the spacing down to about 126 mm, as already mentioned. This is what I did on my Nexus bike.
The Rollerbrake ® is a separate module, and when you buy the hub it is not even installed. (The brake unit would get in the way of fitting the spokes through the hub flange, so it has to be installed after the wheel has been built.).
The new Shimano XT M8100 and SLX M7100 mountain bike groups bring Shimano back into the game. Fortunately, with technology developed for their flagship XTR getting not just used but improved, these two complete groups bring exactly what riders have been asking for.
And they do it at two price points that cover the biggest part of the market. AdvertisementsFor Shimano, it’s about being a complete mountain bike drivetrain and brake system as a group, and giving people options where they’re needed. They’re fully aware of how the other “S” company has affected their market share at the upper end of the market. And how the delays in delivering XTR affected adoption at the highest end.
The new XT and SLX 12-speed groups aim to change that in every possible way.Shimano XT M8100 tech overviewShimano introduced the modern freehub body in 1978, indexed shifting in 1984, Hyperglide in 1989, SPD in 1990. Among other things. Then XTR introduced a whole bunch of new stuff for mountain bike shifting and drivetrain performance. Now, all of that comes together for the best XT and SLX groups ever, with more options for more bikes right out of the gate.
We’ll cover XT first, then summarize the key differences for SLX at the bottom of this post. Photo: S.Lorence/Shimano Hyperglide+ makes its moveHyperglide+ is the evolution of Hyperglide, which was their original computer-designed tooth profile shaping that allowed the chain to move up to a larger cog smoothly without having to first disengage from the cog below it. This meant smoother shifts with no loss in power transmission during shifts. It was a massive improvement in shifting when it was introduced. Had to start from scratch with new shift ramp patterns and designs to accommodate the much larger cassette, so they used that opportunity to redesign HG into Hyperglide+.
HG+ added shaping and ramps to help the chain come back down the cassette to smaller cogs, creating smoother shifts into a harder gear, too. Now, XT and SLX get that, too. Photo: S.Lorence/Shimano XT cranks & chainrings are all about optionsOne of the biggest holdups in getting XTR out was the cranks.
Their two-piece hollow bonded design was gorgeous and light, but proved to be harder than anticipated to manufacture at scale. The solution was a non-series stopgap, and if this new crank looks familiar, it’s because it’s the MT900 crankset that started shipping to get XTR bikes on the market quicker. Now, it finally gets the XT branding it was born to wear.The crankset is a hollow forged design, so it’s one-piece. It’s a good bit heaver than XTR, but a lot less expensive. The most important feature is that it comes with more spindle options. Three in fact, letting you get the one most optimized for your riding style and frame.A 52mm chainline is the smallest they’ll offer, coming on a narrow 172mm Q-factor crankset. They say it works for both standard and Boost axle spacing, which simplifies SKU counts.
If you need a little more clearance at the chainstays for your Boost 148 rear end, like on a burlier all-mountain/enduro bike, they’ll offer a 178mm Q-factor model with a 55mm chainline. And for Super Boost 157mm bikes, they have a 181mm Q-factor crankset with a 56.5mm chain line. And all of these are done with the same crank arms, they just get longer spindleswhich are bonded together, so you’d have to replace the driveside cranks arm to change spindle length.The chainrings are a two-piece construction, which lets them make it far more affordable version that uses a lightweight alloy spider with a steel tooth ring. They’re connected with small fasteners that are not intended to removed. Meaning, you don’t change chainring sizes by bolting on a new tooth ring, you simply swap the entire direct-mount chainring.
Which means you can also put XTR chainrings on it if you want. What about double chainrings?Yep, they’ll have them in both XT and SLX in 36/26 combos. Those will have a 172mm Q/48.8mm chainline for 142 O.L.D. And 178mm Q / 51.8mm chainline for 148 O.L.D. Because some European brands are still spec’ing them. And Shimano’s MTB product manager told us that having that extra capability makes sense in situations beyond mountain biking.
Like, say, if someone can justify the expense of a better bike if they’re commuting to work on it, but then still want something good enough for the trails, too. One bike, two uses, easier to justify to the “accountant” in the family.DCE+ chains make it all possiblePart of the XTR upgrade was adding chain plate shaping into the mix. The chains extended the inner plate to have more precise contact with the chainring’s teeth. This not only helps guide the chain onto the teeth more smoothly, but it reduces wiggle room between tooth and the outer plates. Combined, this is called DCE+ (Dynamic Chain Engagement+) and it’s supposed to reduce vibration and noise.It’s also what allows them to share that 52mm chainline between standard and Boost rear axles without requiring too-long chainstays.
Normally, you want a slightly narrower chainline for standard 142mm O.L.D. Bikes because it better centers the chain with the cassette. But DCE+ supposedly mitigates any off-center issues well enough that you (they) don’t need another chainline confusing their catalog. The real upside? When you do finally upgrade your non-Boost frame, you can (probably) just port this group over with zero issues.DCE+ chains carry over to all of their 12-speed MTB system, the difference is in construction and materials. XTR uses hollow pins to save about 8g and are actually the strongest chains of the bunch. XT chains get solid pins and lose the SIL-TEC PTFE Nickel plating, but keep the stronger Chromizing on the inner plates.XT cassettes make the jump to Hyperglide+We explained HG+ at the start of the post, but if you want to see it in action (and slow motion!), watch that video up top.
For both XT and SLX, you’ll find the same 10-51 and 10-45 gear combos as XTR, and both are now 12-speed only. The larger 10-51 is for 1x drivetrains only.XTR gets three aluminum cogs, then titanium, then steel. XT drops to two alloy cogs at the top (the black ones), followed by all steel cogs for the rest, and SLX gets just one alloy cog, then steel. All three use a special surface treatment to extend the life of the alloy cogs, and all use the same beam support inside to hold everything together.The new XT rear derailleurThe design is very similar to XTR, and all 12-speed rear derailleurs get a new grease inside the clutch that makes it work better than ever. That grease is also available as a service item that your local shop can order and use to service your current Shimano derailleurs, too.Compared to XTR, it’s really just a difference in materials. It still has 13t pulleys for both top and bottom, which helps keep the hanger shorter by increasing wrap, so you can have the chain length you need without sacrificing ground clearance. Shimano says proper chain length is critical to good performance from their 12-speed MTB groups, so if you’re DIY’ing that install, ask your shop for a link to the installation service manual online.
Oh, and make sure the logos on the chain are facing outit’s directional. Fine, I guess I’ll read about the front derailleurNot much to say, really. It’s Sideswing only, multiple mount options (D/E/M), and it has a 10-tooth max capacity. Which works out well since the new groups come with a 36/26 combo. Photo: S.Lorence/Shimano Shape shifting mounts for the ShiftersWhile there is a direct-mount clamp version for XT’s shifter pods (shown above), the real treat is the iSPec-EV version that has 14mm of lateral adjustment, which they say is more than you’d get with individual clamps, and 20º of rotational adjustment.The XT shifters get non-replaceable rubberized thumb paddle contact patch, and the paddle is just a bit bigger than XTR to provide more surface area.
The trigger has two-way release with multi-release (two gears, with the second click being just a bit firmer than the first one so you don’t accidentally over shift.If you are running the double chainring, there’s an XT Rapid-Fire Plus Mono Shifter Lever that lets you shift both up and down with a single thumb leverpush it once to shift from the small ring to the big ring, then give it a little click or pull to release it and shift back down to the small ring. Or, use it for a remote lockout lever on shocks that use a push-to-unlock operation.Brake it down for meLeading up to these new groups, Shimano’s mountain bike groups had been slimming down the mounting clamps in an effort to clean up the cockpit. Which worked, but with the unfortunate side effect of introducing flex to the system, so with 2018’s XTR, they pushed the band clamp inboard and added a support nub to keep it from bending inward toward the grip.The XT and SLX levers have a stiffer lever design with the added support tab, just like XTR. And they get quicker brake engagement with shorter free stroke.
They keep ServoWave, which helps deliver more power later in the lever stroke. Photo: S.Lorence/ShimanoBoth groups now have 2- and 4-piston calipers, and the same lever works for either caliper. That’s an important distinction in that XTR gives you a minimalist “race” lever option for the 2-piston brake, and a full featured “enduro” lever for the 4-piston brake. Photo: S.Lorence/ShimanoXT and SLX come with finned metal pads for aftermarket sales, but non-finned resin and metal pads are available separately and for OEM customers. Like XTR, these use a new resin for the non-metal pad option, and they say it’s “dead quiet”, has great modulation, and is 40% more durable than prior versions. They’re also able to use a lighter alloy backing plate, which helps them cool faster. All models use Shimano’s one-way bleeding.
Photo: S.Lorence/ShimanoXT gets a new Freeza rotor that uses the sandwiched alloy-between-steel braking surface, which is the same as the XTR rotors but without the special heat-dissipating paint on the exposed aluminum fins.BTW, both XT and SLX will have six bolt options, too, but you lose the Freeza fins on those, and the SLX loses the IceTech. Photo: S.Lorence/Shimano Scylence hubs go away. Say hello to silent hubs.So, what about? With the original XTR design, the drive rings would fully disengage when coasting, but they found out that could lead to long term durability issues (you can read about ). The way it worked was that the floating ring has a spring that would pull it away from the fixed ring when coasting to ensure complete separation. And, thus, silence. The problem was, if you suddenly applied a ton of power, the drive rings could slam together, which could eventually wear them out.
The solution was quite simple, they just reversed the spring so that it keeps a very light pressure on the plates. It still relies on the helical splines to push the floating ring firmly into the fixed ring, which has the added benefit of providing massive engagement force.So, technically, now it won’t be perfectly silent, but it won’t be loud. In fact, it makes something like a light hum that’s barely noticeable unless you’re really listening for it. And the faster you go, the quieter it gets.Even though the design is almost identical save for a flipped spring position, it’s no longer called Scylence.
Internally, they’re just called the “100” hub because it has 100 points of engagement. The helical spline adds a bit of rotation to the system, so it ends up with an effective maximum 7.2º of engagement is the most you’ll ever experience.Another unique feature? The drive rings are made out of aluminum, so they’re lighter than steel. Which ends up making for a very light hub, comparable to some very high end hubs from other brands. SLX, XT, MT900 and XTR hubs all use this new design. Photo: S.Lorence/ShimanoThose hubs will be built into new XT Trail Wheels with the wider flange spacing concept that was introduced with XTR’s standalone hubs, except they were actually able to go wider with XTand make it work.
By building it into a wheel system where they knew what spokes and rim were being used, they could bring it all together. The rims are wide, too, which lets them achieve zero dish on alloy tubeless ready rims with a 30mm internal width designed around 2.6” tires. New XT pedals cover all the bases Photo: S.Lorence/ShimanoNew trail pedal with extended platform to provide more support under the shoe, which lets you wear more flexible, more comfortable shoes so your feet don’t get so fatigued on long days. They still have the regular XC-style pedal with no platform, and a clip-free flat pedal that comes in two sizes to fit a wider range of feet. Shimano SLX M7100 tech overviewFunctionally, the new SLX mountain bike group is almost identical. There are a few key differences, though, and of course finishes and materials help them bring it in at a much lower price point.
Surprisingly, there’s not a huge weight gain going to SLX, which means we’ll likely see plenty of mix/match OEM spec on bikes for 2020. Here’s the key differences you need to know:. Chainrings are painted rather than anodized. The SLX chain switches to a SIL-TEC inner plate but has no chromizing treatment. SLX shifters lose the multi-release and instant release, so it only shifts to one harder gear at a time. While you think they should look after your upgrade options 2-3 years from now, that’s not a priority. OEM is their money maker.
If you want them to work together, don’t you want them to work GREAT together? That’s their logic and why they don’t care, because most customers either purchase complete bikes, or complete groups if aftermarket.
For everyone else, they offer discrete clamps.You can still complain, since the freehub is different! They couldn’t overrule space and time to fit a 10 tooth, so they shrunk the spline too!