Dynamo Hub Dilemma

[amasidlover]

I've had a Shimano DH-3N80 for about 18 months now and loved the convenience of just having it there and working with no noticeable resistance. However, the QR skewer has seized into the axle and I've had to shim the QR side and tighten the other with pliers to get it tight in the drop outs. I've been taking it to the North West Mountain Bike centre (NWMBC) who have suggested penetrating oil, patience (several days) and a soft nose mallet - all of which I have now tried. They have also advised that the rim is worn. So...

How do I know when the rim is 'too' worn and how close it really is?

The internals (including axle and QR) for the hub are £40 however, the tool to take them apart is £120 (how Shimano justify this I do not know!!) - So does anyone know anyone (ideally in North West England) with one of these tools and ideally the knowledge to use it?

I could replace the hub (and probably the rim at the same time); if I do this then I have some choices:

1) Bottom end Shimano £30 for the hub - more resistance and may well need replacing again in a year or two...

2) Same Shimano hub again £100 for the hub - providing I don't let it get seized again then it should last years, but if it doesn't I may have to replace it as I can't find anyone to maintain it.

3) A (modern) Sturmey-Archer with drum brake £70 for the hub - Can't find any comparisons of this vs the SON hub or the Shimano plus I don't know if the drum brake is compatible with my 105 STI brake levers. But NWMBC do know how to maintain them if there are issues.

4) A SON hub (28 Classic) £160 for the hub - expensive, but nowhere near the differential I seem to remember when I purchased the Shimano.

I think if I need to build a wheel with a new hub then the Sturmey Archer (if compatible) makes most sense, followed by the SON or the cheap Shimano - the equivalent to my old hub is now close enough in price to the SON to make going for the DH-3N80 pointless.

So is there anything I've not thought of and does anyone know the answers to my questions (rim wear, Shimano dynohub tool and SA drum-brake + Shimano STI compatibility)?

Thanks,

Alex

 

[andrew_s]

To tell how worn a rim is, you can...


Measure the wall thickness with a gauge like this. A rim will fail at about 0.7mm, and should generally be replaced when it goes below 1mm.

Rely on the built-in indicator that most modern rims have. This varies according to brand of rim, and may be either an internal cavity that becomes a visible hole as the metal covering it is worn away, or it might be a groove in the braking surface that vanishes when the sides of the groove wear down to level of the base of the grrove.

Pressure test the rim occasionally (road tyres only). Inflate to 160psi or thereabouts and leave overnight. If it's still whole in the morning, it's OK for a while. Failure renders the wheel unrideable, and costs you an inner tube. Ear plugs are recommended in case it goes bang whilst being pumped.

Hubs:
3N72 for £48 (same drag as your old hub, but heavier, 6€ postage included)
3N80 for £60


The stuck QR:
If you've got to the stage of being about to replace the hub anyway, you might as well get brutal and bash it with a big lump hammer

 

[Piemaster]

If I'm reading your post right, you want a new dynohub and probably a rim. Why not get some new spokes to go with it too?
Have a talk to Spa cycles. You may be pleasantly surprised at pricing for a Shimano option. I've bought 2 dynohub wheels from them (one 700c, one 26"). Can't remember pricing exactly but both were less than £100

 

[amasidlover]

Thanks for the tip on rim wear - I may be able to find a micrometer somewhere I just didn't know how thick a rim should be... The rim is a Mavic Open Pro and from what I can find the rim wear indicator on it, such as it is, is not very useful.

Looks like the SPA cycles deal is very good so I think when my rim needs replacing I'll be going with a 3N72 + Rigida Charida combination. Unless I can find some info on the current generation of Sturmey-Archer hubs....

 

[PpPete]

No rim wear indicator on Open Pro (AFAIK)
Mine are "worn" - as in noticeably concave on the brake track, but still in use because I've checked with one of those gauges (also available on ebay) and its still above 1 mm so chances are its safe.

Not an expensive tool for what it can save you in un-necessary rim purchase.

Also like Andrew S - i'd get brutal with that stuck QR. I've had stuck ones before (not on dynohubs though) - usually cos the skewer is slightly bent and they take a good bit of force to remove. Support the hub as best you can and really wallop it. Or, build up successively thicker shims under the lever side and use the leverage to haul it out bit by bit.

 

[mickle]

I'm loving that Sturmey dyno/drum.

 

[amasidlover]

Which one do you have and do you know if it needs special brake levers or will work with Shimano road STI levers?

 

[mickle]

Brake / lever compatability goes like this:

V brake levers are compatible only with V brakes.

Everything else is compatible with everything else.

Your STI road levers will work with any caliper, cantilever, drum, roller brake and, as far as I know, all cable discs.

 

[amasidlover]

Ah! Thank you - I was hoping that would be the answer. Looks like I may be going for the xl-fdd.

 

[Piemaster]

AFAIK Avid BB7 cable discs come in either road or MTB flavours so I'd assume V-levers would work for mtb V-levers

 

[zigzag]

good article (in german) comparing most popular hub dynamos:

http://nabendynamo.de/service/pdf/ar_09-10_2010.pdf

currently there is a good offer on deore lx dynamos at rosebikes.co.uk

 

[Davidc]

I have 2 low end Shimano dynamos and have been very pleased with them.

I havent had a stuck skewer on a dynamo hub but have on a normal one. The suggestion above - hit it hard - worked on that one and the only casualty was the skewer.

 

[andrew_s]

Thanks for the tip on rim wear - I may be able to find a micrometer somewhere I just didn't know how thick a rim should be

A micrometer isn't very good for measuring rim wear because of having to reach underneath the hook on the inside of the rim, as well as any dishing of the outer side. The same applies to a vernier caliper.
To use these, you've got to arrange something of a known size that fits, and measure that plus the rim. The standard suggestion is either a pair of small ball bearings, or a 2mm gauge spoke bent so that it has 2 short sections parallel to the rim.

 

[Soltydog]

age
Have a talk to Spa cycles. You may be pleasantly surprised at pricing for a Shimano option. I've bought 2 dynohub wheels from them (one 700c, one 26"). Can't remember pricing exactly but both were less than £100

I got my dynamo hub from Spa last year Link £80 & iirc that included post. Still running fine & true. Can't fault it & the resistance is not noticeable to me

 

[GrumpyGregry]

Brake / lever compatability goes like this:

V brake levers are compatible only with V brakes.

Everything else is compatible with everything else.

Your STI road levers will work with any caliper, cantilever, drum, roller brake and, as far as I know, all cable discs.

The vast majority of cable discs are designed to be used with linear pull (V) brake levers.

Avid make BB5 and BB7 in two types. The ones in black is for mtb style applications, flat bars and V brake lever amount of cable pull

The ones in grey is for drop bar applications with sti road levers.