Nexus hub

I'm thinking of converting the xtracycle longtail bike to a hub gear. It gets used and abused in all weathers and typically 3-4 mile trips on flat terrain. Running gear at moment to quote LBS is 'more than a bit worn'.
Idea of a roller brake appeals too, as despite the huge rear disc and a BB5 rear I've never managed to get it adjusted 'just so', it either drags or doesn't do anything appreciable.
So what does the panel think of this coupled with a brake. Enough to do the job? I'm guessing I'll need a chain tensioner too, unless I can get the new Acera rear mech to serve as one (it's newly fitted after a seized chain link bent the old one- 'used and abused')
 

Smurfy

Naturist Smurf
I think the Nexus 8 is internally the same as the Alfine 8, and the Alfine 8 is generally considered a sound, reliable, good value hub. I've got an Alfine 8, not done that many miles, but impressed with quality and shifting.

Check what is the lowest gear you require, as I think there is a maximum recommended torque for the hub gears, although this probably depends somewhat on whether you're a heavy pedal stomper, or a fly weight.

Can't comment on the brake, maybe some useful info here
http://sheldonbrown.com/nexus8.shtml
 
OP
Piemaster

Piemaster

Guru
Hmm. Hadn't really thought about gearing. I was using an Alfine geared bike when working in Aberdeen and had to gear right down in order to get up the hill to work first thing in a morning. Bike had track end type dropouts, so I've not had to deal with a tensioner before. I still have the 700c wheel stashed away but it seems a shame to cut out the hub and get it rebuilt into a 26" rim, plus I could sell it and buy the new Nexus. Alfine doesn't seem to come with an option for a roller brake either.

Bike at present has a, worn, mtb triple front (something like 48-36-22 but not too sure), so I could leave that on to see what suits best before going down to a single chainwheel.
 

tyred

Legendary Member
Location
Ireland
I haven't put many miles on it yet but I have built an old MTB with an Alfine 8 and I love it so far. Such a sweet gearchange.
 

Smurfy

Naturist Smurf
Hmm. Hadn't really thought about gearing. I was using an Alfine geared bike when working in Aberdeen and had to gear right down in order to get up the hill to work first thing in a morning. Bike had track end type dropouts, so I've not had to deal with a tensioner before. I still have the 700c wheel stashed away but it seems a shame to cut out the hub and get it rebuilt into a 26" rim, plus I could sell it and buy the new Nexus. Alfine doesn't seem to come with an option for a roller brake either.

Bike at present has a, worn, mtb triple front (something like 48-36-22 but not too sure), so I could leave that on to see what suits best before going down to a single chainwheel.
Try this to compare existing and Nexus/Alfine.

http://www.gear-calculator.com/?GR=SNI8&KB=36&RZ=18&UF=2130&TF=90&SL=2.5&UN=MPH

And note that if you go below 2:1 for chainring:sprocket ratio, the red 'High Torque!' warning comes on. For example 36:18 is OK, 35:18 and 36:19 are not OK.
 
OP
Piemaster

Piemaster

Guru
Try this to compare existing and Nexus/Alfine.

http://www.gear-calculator.com/?GR=SNI8&KB=36&RZ=18&UF=2130&TF=90&SL=2.5&UN=MPH

And note that if you go below 2:1 for chainring:sprocket ratio, the red 'High Torque!' warning comes on. For example 36:18 is OK, 35:18 and 36:19 are not OK.
Thanks for the link :okay: . Very handy.
Looks like the wheel I linked to and supplied sprocket, coupled with the present big chainring would work and give a reasonable gear spread for my pootling needs.
 
OP
Piemaster

Piemaster

Guru
Finally finished. @Soltydog the wheel came with a shifter - thanks again for the offer anyway, did surprise me the cable was long enough though (just). Weaponised chain tensioner for a £10 off ebay took care of that bit. Not overly impressed with the roller brake, but at least it adjusts ok, which is more than the disc ever did.

Just had lbs fit a new BB and alfine chainset. Mechanic had to fit 39t chainwheel and a couple of shims behind the right hand bearing (new one is external bearings) due to a chainstay clearance issue.An 18t sprocket from the spares drawer is close enough to Shimanos 2.1:1 recommendation.

Only downside now is it's brought the chain closer to the frame and it's rubbing under the 'kickback' xtracycle 2 legged stand. I'll have to see if I can find a lump of plastic to make a chainglider for it once I get back to work.
 
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