Dynamo Hub - New rims or re-build wheel?

[arron-murray]

I am about to set off across the US on my bicycle in the next month or so, and the question is :-

I would like to install a dynamo hub onto the bike. I have looked around and I think I am settled on the SP-PV8. Now, the bike has at the moment a set of Alex Ace 19 36H rims. They look like they are in pretty good condition, but just checking then I can feel one spoke on the back a bit loose.

SpaCycles are doing a deal for a wheel/dynamo set;

Rigida Sputnik 36h / Exal LX17 36h / Exal XR-2 36h (700c) including SP PV8 for £130 which I think is a good price.

Would you just buy the SP PV8 (I get it for £65) and have the hub re-built to the existing rim (£30 for re-build so total comes in at £95) or would you go for the brand new wheel/dynamo offer?

If I do go for a new wheel, it means front and back will be a miss match.

Also, I am fairly new to cycling so does anyone have any advice on the hubs on offer? I will be carrying myself ( 80kg, the bike 15kg and my kit 15-20kg - 115kg total weight)

Thank you

[531colin]

If your rear wheel starts breaking spokes on your Trans-Am. trip, can you repair it at the roadside?
I think you need a reliable back wheel for a long tour (its almost always the back wheel that gives trouble)
Do you really need a dynohub?
Building your old rim onto a dynohub may require new spokes, and the SP hubs have narrow-spaced flanges, if a secondhand rim is less-than-true its a bad choice.

[Brucey]

I agree with Colin; make sure the rear wheel is up to it, that is the one that is likely to give trouble, esp if the load is mostly on the back of the bike.

Regarding front wheel rebuilds, I think you will (if your present hubs are SF and built 36x3) need spokes that are 5-6mm shorter to rebuild the wheel with a PV8 hub 36x3. It also looks like you can't fudge it by altering the crossings, because that makes the wrong amount of difference.

cheers

[pwa]

One thing that can really ruin a cycling holiday is spokes breaking one after the other in the rear wheel. If in doubt I would get new wheels, front and rear. If you can get the rear wheel tweaked to be spot on, fair enough. But if you are unsure, a new rear from a good maker (like Spa) would be a great idea. I'd just get a new front one anyway if you want a dynohub, but do you really need one? Do you tour at night? I never do. Or maybe you are looking to charge a GPS. But whatever you do, don't risk using wheels you are not confident with.

[martinn]

If you decide to go for the Dynohub, I would look at the Shimano XT from Spa. The SP hub is NOT user serviceable so if it goes wrong, you will need a new wheel. The shimano on the other hand can be serviced, so if it goes wrong there is more chance of a fix.
If you want a bomb proof dynohub then go for the Son 28.

Do you know the history of the wheel, how old are they and who built them.
If in doubt I would go for a rear hand built from Spa, tell them what you want if for and listen to their advice.

For the small amout of additional cost compared to the total cost of the trip/ inconvenience, I would go for a brand new wheelset.

The question comes back again to the reason why you would want a dynoHub? Charging devices/ running lighting/ charging powerbank, all the formentioned?

Martin

[PH]

I'm not sure what the price comparison is, does it include re using the spokes? Which as pointed out won't be possible, so the difference will at best be the cost of the rim about £25. Even if you knew you'd end up with a perfect wheel, that price makes it simple for me, get a complete wheel and you've kept a spare.

If I do go for a new wheel, it means front and back will be a miss match.

There is no reason they need to match, I don't think any of mine do, some by design others because that's the way it's worked out. Each wheel chosen for it's purpose, rim, spokes, build, it's easy to see why they'd be different.