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Commuting Bicycle commuting is easier than you think, before you know it, you'll be hooked. Learn the tips, hints, equipment, safety requirements for safely riding your bike to work.

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Old 03-02-09, 02:48 PM   #26
wahoonc
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Originally Posted by PaulRivers View Post
I just don't understand how it could be "just different", seems like either it stops the bike quickly or it doesn't, and I've read (though have not tried myself) that it doesn't. It sounds like from your post that you acknowledge that it's a pretty weak brake, to. I mean, you'll adjust to any braking system to a certain extent by giving yourself more space and braking sooner I guess...but a much longer stopping distance is "terrible" IMO. I consider stopping with my rims brakes in the rain to border on a "terrible" stopping distance, to be fair...

It also seem like if you're running a front non-coaster brake, you've defeated the point of having a coaster brake - 1, less maintenance, replacing pads, etc, and 2, same performance in the rain. Might as well just put rim brakes on both and get better stopping distance in dry weather.
Different riding styles, also try stopping a rim brake bike with just the rear wheel....takes quite a bit more distance than using both brakes. The point in having a coaster in the rear and a drum/roller up front is safety and maximum braking power when needed. You use the coaster for slowing down, stopping from slow speeds, if you need maximum braking power go for the front brake, chain jumps or breaks go for the front brake. FWIW my roller brakes are all but maintenance free, a bit of grease and a small adjustment and they are good to go. No wear out parts that I am aware of.

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Old 03-02-09, 03:52 PM   #27
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Originally Posted by K6-III View Post
For 120mm spacing, the only off-the-shelf 8 speed hub is Sturmey 8. Now that the updated model is shipping, that might be your best option.
Unless they've changed it in the updated model, the SA 8-speed has 1st gear as direct drive, so you need a tiny chainring/huge cog to get a sensible range of gearing. It's basically designed for folders with small wheels.
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Old 03-02-09, 06:05 PM   #28
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On one of my bikes I have put a Nexus 8 Redline with a hand lever operated roller brake. On the front I have a cable operated disc. The rear brake was always very poor until I read somewhere that you should use canti-brake levers with them rather than v-brake levers. I had a pair of them old Shimano levers that could be set to either and I now have them on the bike. With the front set at v-brake and the rear set at canti-brake (long pull & short pull), both brakes work just fine. I can lock the rear wheel in the dry if I grab a handful.

BTW- my Nexus 8 Redline is 132mm so needs a couple of washers to take it up to 135mm. My new Alfine is 135mm already.
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Old 03-02-09, 06:55 PM   #29
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I wanted to put this in the rear of a 120 spaced bstone track frame as a fun way to change up the bike when i get tired of having my second bike be fixed (which happens about 10 times a year). I thought the 7s and 8s where closer to 120; maybe 125 or 128 where i would only have to coldset my rear triangle. I have a nexus 3spd thats 120, but id really rather go with a full range of ratios. Anyone know if i can respace the 8 nexus to get it closer to 120ish?( i bet the alfine is way out of my spacing league).
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Old 03-02-09, 11:10 PM   #30
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Originally Posted by elbows View Post
Unless they've changed it in the updated model, the SA 8-speed has 1st gear as direct drive, so you need a tiny chainring/huge cog to get a sensible range of gearing. It's basically designed for folders with small wheels.
SA makes 30t and 33t cranksets for just this purpose.
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Old 03-03-09, 10:48 AM   #31
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Originally Posted by sstiletto View Post
On one of my bikes I have put a Nexus 8 Redline with a hand lever operated roller brake. On the front I have a cable operated disc. The rear brake was always very poor until I read somewhere that you should use canti-brake levers with them rather than v-brake levers. I had a pair of them old Shimano levers that could be set to either and I now have them on the bike. With the front set at v-brake and the rear set at canti-brake (long pull & short pull), both brakes work just fine. I can lock the rear wheel in the dry if I grab a handful.

BTW- my Nexus 8 Redline is 132mm so needs a couple of washers to take it up to 135mm. My new Alfine is 135mm already.
This is a good example of what I was saying - if you have a non-roller front brake anyways, it seems like all the advantage of a roller brake are lost (no maintenance, equal performance in wet weather) and you might as well go for the superior stopping power of rim or disk brakes.

If you have a roller or drum brake on the front as well, well, that has a certain logic to it at least...
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Old 03-03-09, 12:51 PM   #32
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...the SA 8-speed has 1st gear as direct drive, so you need a tiny chainring... to get a sensible range of gearing.
Ah, like the inner chainring fitted on almost every touring bike, mountain bike or hybrid.

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Old 03-04-09, 07:23 AM   #33
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I did originally build the bike with two hand lever operating roller brakes as a low maintenance option. Unfortunately, I used a pair of v-brake levers and both brakes were rubbish. That's why I put the front disc on. I may re-try the front roller brake sometime but using canti-levers.
I dislike rim-brakes and try to avoid using them on the bikes I build.
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Old 03-04-09, 01:49 PM   #34
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I wanted to put this in the rear of a 120 spaced bstone track frame as a fun way to change up the bike when i get tired of having my second bike be fixed (which happens about 10 times a year). I thought the 7s and 8s where closer to 120; maybe 125 or 128 where i would only have to coldset my rear triangle. I have a nexus 3spd thats 120, but id really rather go with a full range of ratios. Anyone know if i can respace the 8 nexus to get it closer to 120ish?( i bet the alfine is way out of my spacing league).
The freewheel SRAM P5 5 speed is 122mm OLD. I have it one one bike with 120mm dropouts, a track style steel frame. I chose it so I would not have to change dropout width as I wanted the capability of mounting the original FG rear wheel or a S3X hub wheel when it becomes available. The P5 has the same overall gear range as the Shimano 7 speed, about 250%.
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Old 03-04-09, 03:32 PM   #35
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I read last night that the coaster version of the nexus 8 spd was spaced at 120 with an overall axle length of 132 which is weird because the non-coaster v brake version is said to be spaced at 130. BTW i also road a Nexus 8 roller last night and fell in love. The range is perfect, the shifter is above par, I am in love. I am getting the spacing info from JandB; can anyone confirm?
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Old 03-04-09, 06:18 PM   #36
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I read last night that the coaster version of the nexus 8 spd was spaced at 120 with an overall axle length of 132 which is weird because the non-coaster v brake version is said to be spaced at 130. BTW i also road a Nexus 8 roller last night and fell in love. The range is perfect, the shifter is above par, I am in love. I am getting the spacing info from JandB; can anyone confirm?
Shimano Europe has the specs for the Nexus 8 speed coaster brake hub, SG-8C31, posted. Looks like they have the OLD and axle length dimensions reversed as the OLD is 184mm and axle length is listed as 132mm which makes no sense. Here is the link if you want to take a look.

http://cycle.shimano-eu.com/publish/...31.-type-.html
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Old 03-04-09, 06:31 PM   #37
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Here is a PDF document from Shimano which lists the OLD for ALL of their recent gear hubs. None except some 3 speeds for 120mm dropouts. Some of the 7 speeds are 127mm. Everything else 130mm to 135mm.

http://bike.shimano.com/publish/cont...Dimensions.pdf
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Old 08-01-09, 08:27 PM   #38
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I have a bike with an Nexus 7 that I use for commuting duty. Today, I tested a new bike with a Nexus 8 at the LBS. One thing I noticed with the 8 vs. my 7 is that it is a lot quieter when coasting (good!). However, there was a clunking when shifting from gear 3 down to gear 2. Kinda bothered me so I didn't buy the bike. All the other upshift/downshift combos were ok.

Do you think this could be fixed with a cable adjustment or greasing up the internals? Or, is it something that is wrong internally with this hub? I told the sales guy about this, but he didn't know much about internal hub bikes. I wanted to mention it to the wrench, but he was really busy.
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Old 08-01-09, 10:19 PM   #39
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Awesome thread & thanks for reviving this, ShinyBiker!

We were just discussing the difference about Nexus 8 vs Nexus 8 Premium.
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Old 09-28-11, 07:16 AM   #40
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Firstly my apologies for bumping such an old thread but after doing some searching this thread seemed to give a lot of very useful information on the Shimano hubs so thought it best to post here.

I have recently bought a Trek Soho Deluxe 2011 which is a belt drive bike with the Shimano Nexus-8 rear hub (the non redline one), rear rollerbrake and an Alfine eight speed shifter. From the outset third and fourth gears have been a bit grindy and I can feel some vibration through the pedals so it's been back to Shimano and received it back today but there doesn't seem to be any difference, if anything I'd say it's a little worse as eighth feels a bit rougher. My local bikeshop have been very helpful but where I live is relatively remote and I don't think the shop has seen much of these hubs, similarly I've never had a gear hub before so I don't know if this is normal? I tend to avoid these gears as others are incredibly smooth particularly 5th.

If this is normal then it sounds like from here the red line Nexus 8 hub would be worth changing to as it's sealed and should last longer plus it should be an easier swap as it has a rollerbrake option? I've looked at the Alfie hubs but as they need a disc I'm assuming they'd be more work to swap out although I don't know how feasible it is to swap the Nexus hub bearing in mind it's obviously attached to the wheel?

Thanks for any advice,
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Old 09-28-11, 04:30 PM   #41
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I have a few IGH bikes, and the more I deal/hear about issues and solutions the impression I get is that if you or your LBS dont already have extensive knowledge of the innards of these hubs and know about the obscure sources from which to find the various internal components that will allow a rebuild or repair you are often simply confronted with the only sure option of replacing the whole thing.

In my modest time about bicycles, there just doesnt seem to be broad resources for every one to allow them (LBS mechanics also) to stop, strip, rebuild...I often find that most dont know much about dealing with them beyond adjusting for cable slack to be honest.

I have no doubt that there is some (or a number) of folks here that at total wizards and know these things inside and out and also have the 411 on where/who to contact about parts/tools/supplies and process to service and rebuild.

I would think that with your recent purchase, your bike will still be under warranty and if there was some unfixable/unresolvable issue then the LBS should be able to confer with Trek and get you a new wheel/hub..I would think..

Perhaps someone else with this hub can chime in on what they experience with regards the traits they have. Few are perfect to be honest. The 3-speeds tend to clack-clackety-clack all the time (physical trait of helical gear engagement as I understand), the alfine in my experience has been utterly silent, but like the nexus has some weight to it, also the gearing spread is good but not quite 'perfect', etc..

Good luck. If the bike is still under warranty I would see about having a word with your LBS to see about the option of pursuing that avenue of resolution. Hopefully it'll be smooth and easy..
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Old 07-25-14, 11:59 PM   #42
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I have just aquired a Nexus SG-8R20. It's used but not very much. It is the future replacement for my Nexus 7, which has long served me trustilly and faithfully. According to sources (Sheldon Brown is one) this version of the hub (SG-8R20) doesn't have a roller clutch. It apparently has 'pawls' only.
I have looked at drawings of the internals (Shimano). My question is, is the roller clutch the band of cylindrical bearings between the internal cyclinder and the hub case?
In which case I cannot find a drawing of a SG-8R20 that doesn't have these roller bearings.
I can understand in principle why a roller clutch is better at changing gears under pressure. And this Nexus SG-8R20 feels dodgy pushing down and changing. I was very surprised as I have used a Nexus inter 7 for 10 years and that hub is silent and you can change going up hill with no clunking.

Doe the inter 7 have a roller clutch? What actually is a roller clutch? Should I get rid of this version of the Nexus 8?

And also I have to add that coaster brakes are the only way to slow down. Why anyone would bother with rear rim brakes is beyond me. But please focus on the 'clutch' question, not on brakes.

Thanks.

Last edited by gate28; 07-26-14 at 12:07 AM.
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Old 07-26-14, 12:16 AM   #43
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Quote:
Originally Posted by gate28 View Post
I have just aquired a Nexus SG-8R20. It's used but not very much. It is the future replacement for my Nexus 7, which has long served me trustilly and faithfully. According to sources (Sheldon Brown is one) this version of the hub (SG-8R20) doesn't have a roller clutch. It apparently has 'pawls' only.
I have looked at drawings of the internals (Shimano). My question is, is the roller clutch the band of cylindrical bearings between the internal cyclinder and the hub case?
In which case I cannot find a drawing of a SG-8R20 that doesn't have these roller bearings.
I can understand in principle why a roller clutch is better at changing gears under pressure. And this Nexus SG-8R20 feels dodgy pushing down and changing. I was very surprised as I have used a Nexus inter 7 for 10 years and that hub is silent and you can change going up hill with no clunking.

Doe the inter 7 have a roller clutch? What actually is a roller clutch? Should I get rid of this version of the Nexus 8?

And also I have to add that coaster brakes are the only way to slow down. Why anyone would bother with rear rim brakes is beyond me. But please focus on the 'clutch' question, not on brakes.

Thanks.


I went from coaster on rear to front and rear rim brakes. Internal braking mechanisms add weight, complexity, and often noise depending on the specific design. If you lose the chain, you lose braking. Had that happen to me a number of times, so i'm glad to be on something not reliant on the drive system. I wanted a really good rear internal hub, and thats what i got, and though i was hesitant at first, and though in downpours the friction can be a small issue, it's better than suddenly having no brakes at all, over a bump or road hole for example.

Some designs i've seen lately have moved the rear caliper down onto the chainstays, allowing the shift and brake cables to go down the diagonal vs across the top tube. Cleaner, uses less cable & sheathing, and no welded on mounts to dig into your shoulder when you carry it.

- Andy

Last edited by TransitBiker; 07-26-14 at 12:22 AM.
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Old 07-26-14, 01:01 AM   #44
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Dude, I am asking about roller clutches. Brakes are another subject.
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Old 07-26-14, 01:08 AM   #45
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Dude, I am asking about roller clutches. Brakes are another subject.

The graphic answered that, and the rest was my comment on the rest of the thread & not related to your post.

- Andy
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Old 07-26-14, 07:31 AM   #46
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Just to update my post a few years late, I had the hub sent back again and they found there had been an issue with the way the hub was set up and basically replaced most of the inside of it due to the damage caused by the original fault. This time the hub was noticeably better and a couple of years later of daily cycling is still running well.

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Old 07-26-14, 04:05 PM   #47
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Doe the inter 7 have a roller clutch? What actually is a roller clutch? Should I get rid of this version of the Nexus 8?
These guys would prolly be able to answer your specific questions:
https://hubstripping.wordpress.com/n...ter-8-shimano/

Also,have you checked the tech docs? Here's the one for your Nexus 8:
https://www.paul-lange.de/support/sh...tthandbuch.pdf


Quote:
Originally Posted by TransitBiker View Post
If you lose the chain, you lose braking.
Only coasters,roller and drum brakes are unaffected by the chain.
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Old 07-27-14, 10:18 AM   #48
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Originally Posted by gate28 View Post
I have just aquired a Nexus SG-8R20. It's used but not very much. It is the future replacement for my Nexus 7, which has long served me trustilly and faithfully. According to sources (Sheldon Brown is one) this version of the hub (SG-8R20) doesn't have a roller clutch. It apparently has 'pawls' only.
I have looked at drawings of the internals (Shimano). My question is, is the roller clutch the band of cylindrical bearings between the internal cyclinder and the hub case?
In which case I cannot find a drawing of a SG-8R20 that doesn't have these roller bearings.
I can understand in principle why a roller clutch is better at changing gears under pressure. And this Nexus SG-8R20 feels dodgy pushing down and changing. I was very surprised as I have used a Nexus inter 7 for 10 years and that hub is silent and you can change going up hill with no clunking.

Doe the inter 7 have a roller clutch? What actually is a roller clutch? Should I get rid of this version of the Nexus 8?

And also I have to add that coaster brakes are the only way to slow down. Why anyone would bother with rear rim brakes is beyond me. But please focus on the 'clutch' question, not on brakes.

Thanks.
Did your 7 make a click-click sound like a typical bike when it coasted? My Alfine and my Nexus "Red Band" were virtually silent when coasting.

Anyway, I was curious too and this is what I found.

Edited: This is a partial roller clutch Shimano hub (in not so great shape):



This is a full roller clutch 8:




They both have roller bearings around the wide part of the hub. But on the non drive side of the hub they are different.
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Last edited by tjspiel; 07-27-14 at 05:46 PM.
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Old 07-27-14, 11:27 AM   #49
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yea, SA 8 you take off axle nuts from the left side and look for thinner ones ..

their 5 speeds are made in 111 width as per the website ..
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Old 07-27-14, 03:06 PM   #50
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...And also I have to add that coaster brakes are the only way to slow down. Why anyone would bother with rear rim brakes is beyond me....
I like roller brakes and drum brakes more than coaster brakes. If you have a 8R20, it should take a roller brake. It's the 8C20 that has a coaster brake.
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