derekzzzzz
new member
Reged: 05/13/06
Posts: 4
Loc: UK
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Hi!
I recently bought a Carrera Subway 8, which uses the nexus SG-8R25 for it's gear mechanism.
I find all the gears engage instantly, except 5th. Sometimes I pedal a further 10 or so revolutions before 5th engages. It doesn't happen every time, but often enough to spoil my cycling.
Halfords replaced the rear wheel for me today but I still have the same problem. They told me they will discuss it with Carrera. Halfords have so far been great about it, so I'm not flaming them here, I'm simply wondering if anyone else is aware of this problem?
Great bike, and I really like the feature of being able to change gear when stationary, as I frequently get stuck in London traffic in the wrong gear! But this problem with 5th is really spoiling it for me. I notice on the Shimano website, in the tech details, that 5th uses a 1:1 ratio, but don't understand why this should affect the gear in this manner.
Can something else be the cause of this, or am I going to have to modify my cycling technique to work round it? The other option will be to try to get a replacement bike, but there are other options I would rather explore first.
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Insightdriver
captain
Reged: 03/07/04
Posts: 472
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I'm not familiar with the nexus system so I can't be of much help. I have the Shimano site up and am looking at the hub. Seems to me if you only have a hesitation in one gear, and the hub was changed, then the cable or shifter are the culprits using just logic. I hope someone else on this site may be of more help but this site is not a very busy one. You may get more information on a larger cycling site in the UK, I suspect. Good luck.
If you are the handy type, you might check out Sheldon Brown's site that shows the mechs of the Nexus hub and system>
http://www.sheldonbrown.com/nexus.html
Otherwise your bike shop must be in a learning curve for this setup. From what little I've read so far, it's quite slick. Not only that, it seems it's top of the line of Shimano internal hubs.
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derekzzzzz
new member
Reged: 05/13/06
Posts: 4
Loc: UK
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I hadn't realised Sheldon had a page dedicated to my gear ,thanks for that. I like the way he compares it to the 3 speed bikes that were around, when I was a boy!
I'm hoping you are right and that this is simply a case of my bike shop being on a learning curve as well. They are a National Chain in the UK, for what that is worth!
Given that the bike I bought is "not" cheap, and this Shimano gear set is the major cost component of the bike, I'm sure it must come down to something not being right, I can't believe this is the way the bike is supposed to be.
I certainly won't keep it if that is the case, but for now, patience is the name of the game, and I'll wait and see what they tell me next week. They are going back to the manufacturer of the bike, who will no doubt contact Shimano. They want to try a third new wheel as well, just to be sure, so I have go to along with that as well! At least I can still use the bike, although I'm now losing confidence in the gears incase I don't get that burst of speed just when I need it. Cycling in Central London has it's challenges, and not being able to rely on your gears is not good for one's nerves!
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Dave_Thompson
prophet
Reged: 12/19/03
Posts: 717
Loc: Spokane, Washington
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It would seem to me, that if you had the same problem with two different rear wheels, it may be an adjustment problem rather than a hub problem. The Nexus hubs have a reputation of being quite good.
Is your shop merely changing wheels and then kicking the problem up to Shimano? Here in the U.S., the more likely course of action, unless the unit were clearly defective, would be to have a skilled mechanic try to make the necessary and proper adjustments until things are right, and only then would Shimano be called into the play. You might owe it to yourself to press Halfords to participate more, rather than shifting the problem to the manufacturers, at least until the fault is determined.
--------------------
Steel lover, but then I like Ti with carbon too.
Licensed bike geek.
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Insightdriver
captain
Reged: 03/07/04
Posts: 472
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From what I read on the Shimano site, set your bike in fourth gear and look at the index marks which I believe are yellow. They should line up perfectly. That seems, as far as I can tell, the only adjustment necessary.
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derekzzzzz
new member
Reged: 05/13/06
Posts: 4
Loc: UK
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Yes, the two yellow dots line up just fine when in 4th.
I think the answer is that this is the way it is with this mechanism, and that I can either modify my cycling technique slightly, or have the bike replaced. Halfords are still prepared to swap the bike for me. I've tried a few other bikes now and spoken to some other vendors in the UK. I spoke to two people whom I saw with similar gears and they had no issue at all. So it must be me!
I do like the bike though, so have decided to stick with it. I am changing up to 5th at a lower speed, and can also time my gear change so I can at least stop pushing on the pedals for a moment. I do find that if you change gear when putting a lot of pressure on the pedals, particuarly when going uphill, it can generate a clunk a short while later(sometimes up to 10 seconds or more) but again I can avoid this more now that I understand how the mechanism behaves on the road.
I'll see if the behaviour changes in any way as the bike gets older, but for now, I will continue with my modified cycling technique in order to get the best of out it. I'm already noticing more subtle changes than I recall with standard MTB gears, and it is indeed time for the bikes first service. The yellow lines do line up but I am noticing different noises which suggest to me that the gears do need adjusting.
Would I have bought the bike knowing all this beforehand, well I'm not sure, but I'm committed to keeping it now.
Back in 6 months with an update............
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PJR
new member
Reged: 07/30/06
Posts: 1
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Sorry if this is a bit late for the thread.
I think there are two problems here. The first is that the gear changes should be made while taking pressure off the pedals or by backpedalling. This is how it was with Sturmey Archer gears. There is no need to maintain pressure because the gears are spring-loaded to change up or down.
With the second problem, changing into 5th gear, I had the same with changing to 4th. I checked that the two yellow marks lined up and then took up the slack in the cable by adjusting at the top, little by little.
However, I found that the problem recurred if I left my hand on the gear-change after the "click". What I think happens is that if pressure kept maintained on the control, then it is transferred to the cable and the gear does not engage properly.
Since keeping all this in mind, it workes properly now.
Hope this is of use.
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derekzzzzz
new member
Reged: 05/13/06
Posts: 4
Loc: UK
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Hi PJR,
I would agree with what you say regarding the gear changes. Now that I have got used to it I rarely have a problem.
It's not quite as perfect as I would like, but I've not once encountered a situation where I have ended up in "no" gear, so I'm now happy I made the right choice, at least for the type of cycling I'm currently involved in.
As an aside, the Mayor of London is starting a crackdown on cyclists who cycle on the pavement and go through red lights! A survey he quotes says that one in three cyclists now ignore the traffic lights, but I reckon they have seriously underestimated the number!
So if anyone is cycling in London over the next few months beware or you may recieve a fine you were not expecting.
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shedloads
new member
Reged: 09/19/06
Posts: 1
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Hi Derek
You seem to have mainly resolved your problems using the Nexus 8.
I have had a Subway 8 for about 15 months over 1500 miles and have had no problems shifting gears. I have found though as a previous poster has suggested that if I keep pressure on the shifter after changing gear there is sometimes enough pull on the cable to slightly disengage the gear. Perhaps you were doing something similar. As long as the alignment is correct in 4th gear then all the other gears come sweet, so another thought is that maybe your shifter is slightly out in 5th gear and needs replacing.
The SG-8R25 is an excellent hub and I have found it to change well under load and there is certainly no need to back pedal.
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