I’ve got some old Bontrager Race X Lite road wheels, these ones:

The rims are showing a lot of wear, I’ve not asked Trek, but suspect even if rims are available they’ll be comparatively expensive. I’m wondering about getting some LB/Nextie/Farsports carbon rims to rebuild them. What do we think are the odds that another 24mm deep rim will have the same (or close enough) ERD? To my mind it’s got to be close, otherwise you’d have issues with how much nipple is sticking out and what not.

Yes, I could just measure my current rims, but that involves taking them apart! I know spoke lengths, but they’re custom straight pull Bontrager DT240s, so I haven’t got the relevant measurements for those, and I don’t even know how to measure SP hubs! Indeed the DS flange on the rear is actually a normal one, just to make it more fun.

Because of the SPness of them I’d quite like to get it right, I know spokes are easier to come by than they were, but not exactly ubiquitous still. They’re DT Aerolites too, so it goes from being a cheap and simple exercise to a rather more complex and expensive one.

Considering the spokes are evenly spaced at the hub, but then “paired” at the rim, I’d guess they’re very slightly longer than a conventional radial lacing? Which I’m guessing could have a small impact. Then again, I’m guessing (see a theme?) that the wall of a carbon rim will be slightly thicker and I’d expect a slightly larger ERD, so that may not be a bad thing.

Any thoughts…?

In your shoes I’d gamble on it being close enough. I’ve built hundreds of wheels and several with spokes that were some way off the correct calculated spoke lengths and it’s surprising just how far you can get without problems.

Your logic that ERD may be more for the carbon rims isn’t unreasonable but I’d suggest that it’s likely to be an advantage in that you can quite happily build wheels with several threads showing on the spokes (depending on the nipple design of course but most have plenty of thread in). Not to mention that you can get nipples in different lengths.

You could get a decent idea of the ERD just by taking the tyre/rim strip off I’d have thought though.

Mmm, that’s my logic. I must say that as they’re for me “close enough” is fine – may go brass nips to give a bit of extra strength as I’ve just rebuilt my LB rear wheel, alu ones kept breaking as the LB ERD was somewhat ‘conservative’ and thus spokes were extremely short!

I did wonder if you could measure in situ – ERD = distance between opposing nipple ‘ends’ + 2x length of nipple…? Bit of a moot point as you seem to not be able to trust the ERDs the Chinese guys print anyway.

Likely to go tubs for some superlight wheels for very little money, so not something which will see huge amounts of use.

Ignore that. Misunderstood what you’d typed.

No mathematical back up, but I would guess that swapping from paired spoke arrangement could be as much an issue as the rim.

Not looked at it , but this claims to cover spoke calculation for paired spoke arrangements so you could see how much of an issue it might be.

http://www.mrrabbit.net/wheelsbyflemingapplications.php

It would give some extra length in the spokes if you went to a ‘conventional’ radial arrangement, but I’m not sure how much. I don’t think it is very much.

That sheet only gives 1 or 2 cross options for paired holes, does that mean radially laced paired spokes versus ‘even’ spread makes no difference?

It’s only the DS rear which is crossed, all others are radial.

Edit: reading about it more, that says you need different length spokes on each side for a paired spoke design, according to the decals which list spoke lengths on the Bonty wheels (good idea that) mine are the same all round on the front, and the usual L/R split on the rear.

I think I may just have to have a go!

njee20

Your best bet would be order the rims then measure their ERD when they arrive.

The front hub in appearance looks like the DT Swiss 240 straight pull hub shell re badged so you may be able to find the dimensions for that one on the DT Swiss spoke calculator or at worst give you something to compare measurements to. This may then allow you to figure out the NDS of the rear hub.

Once you’ve got the measurements you can lace them how you want them and order the spokes you need for what you want.

Your best bet would be order the rims then measure their ERD when they arrive.

The front hub in appearance looks like the DT Swiss 240 straight pull hub shell re badged so you may be able to find the dimensions for that one on the DT Swiss spoke calculator or at worst give you something to compare measurements to. This may then allow you to figure out the NDS of the rear hub.

Once you’ve got the measurements you can lace them how you want them and order the spokes you need for what you want.

Aye, I’m trying to avoid that though, I don’t really want a set of rims sat about that I then have to build. If they’re a straight-ish swap it seems a prime opportunity to do this, if it works! I’m also not fussed about trying to order spokes – they’ll be expensive for Aerolites, and straight pull ones aren’t that easy to find. Jenson USA list them for $74 a box, and I’d need 3 boxes.

If it’s a case of £100 on Bontrager alu rims or £200 on Farsports it’s an easy choice, if it becomes £200 on rims and £ £150 on spokes, leaving me with a load of redundant ones I’m not bothered, I’ll just rebuild on the Bontrager rims. The hubs are nice, but aren’t really worth all that – I could just buy another pair of SP DT240s, or more realistically if I had a hankering for some crazy light tub wheels just buy complete from Far Sports, and sell the Bontragers.