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A Minging Manc...
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- Sunny Ashton-under-Lyne
Just finished a wheel build for my 2017 GT Grade carbon. Things were a bit complicated as it is something of a transition bike and can perhaps be described as an early 'Gravel' or 'All-road' bike and had a funny spec of disc brakes with a 135mm QR rear hub and 15x100mm thru-axle front hub. Made a few discoveries along the way that are worth sharing so putting them here so people on the wide-web might find them if needed.
The OEM Mavic wheels were starting to give me cause for concern as the rear wheel in particular had developed an annoying tick over a year ago which has steadily got worse until I eventually found 2 loose spokes. Not an issue until I tried to re-tension them, only to find that the nipples were well and truly locked/seized onto the straight pull spokes. after a good long soak with oil I got one freed off (having to grip the spoke with vice-grips), but the other sheared off at the nipple. The wheels are effectively scrap as the Mavic spokes are stupidly expensive and all in a similar state, so a single spoke replacement still leaves me unable to true the wheels (Weirdly, despite the two loose NDS spokes the wheel was still true, probably because the wheel is so heavily dished that the NDS spokes are actually doing very little! I have felt/heard the wheel flex once or twice when under duress).
The world seems to have moved on to 12mm thru-axle front and rear now and I did build some 12mm thru-axle wheels for my commute bike using Shimano 105 hubs, but searching for a 135mm QR disc Shimano hub only comes up with XT mtb options, either the old style M756 with 6 bolt disc mounting ( I have used this for various MTB and commuter wheel builds in the past), or the current M8000 which is centrelock disc mount so matches the Mavic hub I am replacing. Front hub was relatively simple and was dictated by my desire to only have 28 spokes at the front with 32 Rr. This means the hubs are not a perfect match as the 28h hub was dropped from the latest generation.
I ordered my hubs and revelled in the sparkly shinyness when they arrived..... I then ordered my rims. Until my last set of wheels I have always used Mavic rims and never been disappointed..... until I used a set of Open-Pro disc rims that started splitting around the nipple holes within months!!!! I then discovered on the web that I was not alone in this and the rims have a hopelessly low max spoke tension rating and the problem was common. The Open-Pros were replaced with DT rims and problem solved. For some reason I decided to give Mavic a second chance when I found the Gravel/dirt A1022 which sounds perfect for my intended use this time around....
So perfect? Strong, light, easy to get tyres on/off and designed for a bit of rough treatment. I hope my choice of Mavic doesn't come back to bite me!
When the rims arrived something odd caught my attention. The spoke holes were way off centre, in fact the rim profile was skewed to one side. They were assymmetric! I have checked all the retail info and even Mavics own spec pages and NOWHERE is this mentioned, you'd have thought they might tell you such a key fact? Anyway, not a problem, actually a bonus as this would improve the strength of the wheels due to the reduced dishing requirement.
So there is interesting interweb fact #1 for anyone who stumbles across this. Mavic A1022 rims are asymmetric, although it looks like they are no longer made so stock seems to be drying up now? Also, beware because this might bother you, due to the reversed flange offset from front to rear hubs you will need to mount your rims the opposite way round Fr-Rr. If like me you have minor OCD tendencies you could find this upsetting. I can tolerate it only because I know it is technically the stronger solution....
I ordered my spokes and built the wheels. They are probably technically the best wheels I have ever built. First time I have used asymmetric rims so spoke dishing while not equal is pretty good. I got my spoke lengths spot on so thread finishes flush with the top of the spoke nipple and for the first time ever I paid attention to which spokes were leading and which trailing so the wheels are hopefully best suited to handle drive force at the back and braking force at the front. Despite not building for weight reduction, using more spokes than the 24Fr/24Rr original wheels and MTB hubs rather than road versions my wheel build has knocked 150g off the wheels.
Now for interesting discovery/fact #2. When I built up the wheels with tyres, discs etc it was only when I came to finally mount the 105 11-32 cassette that I found something else was amiss. The cassette lockring wouldn't engage with the freehub. It was almost midnight at this point so I initially thought I must be mistaken or doing something wrong, but no, no matter how I tried the threads just weren't even close to catching. A short while later, vernier caliper in hand I found the reason. The freehub body was 2mm shorter than the 'normal' one. The 'normal' freehub that has been the shimano spec suitable for 9/10/11spd cassettes for years was apparently different on this current XT hub and this was news to me. Turns out Shimano have reduced the cassette body by 2mm to 35mm for 11spd MTB while sticking with the 37mm freehub for its road groupsets (105/ultegra/etc).
***EDIT: Turns out I got this slightly wrong. Just done some additional reading (as well as measuring the freehub depth on one of my XT M756 hubs) and it looks like freehubs were always 35mm deep but Shimano went to 37mm for 11spd road cassettes while retaining the 35mm set-up for MTB by slimming down the cassette spider as I have done.***
Options at this point were limited and not very appealing;
Trial mod has been done (thanks to a work colleague who has a DIY CNC machine in his garage!!!) and fits/works perfectly so I just need to get my spare cassette machined to match now and that should be me set for another 4-5yrs at least before I need to get any further cassettes machined.
I apologise for the rather long and possibly boring thread, but this info just doesn't seem to be out there so someone is bound to find it useful, especially if you want to run normal/sensible cassette ratios on an MTB hub
The OEM Mavic wheels were starting to give me cause for concern as the rear wheel in particular had developed an annoying tick over a year ago which has steadily got worse until I eventually found 2 loose spokes. Not an issue until I tried to re-tension them, only to find that the nipples were well and truly locked/seized onto the straight pull spokes. after a good long soak with oil I got one freed off (having to grip the spoke with vice-grips), but the other sheared off at the nipple. The wheels are effectively scrap as the Mavic spokes are stupidly expensive and all in a similar state, so a single spoke replacement still leaves me unable to true the wheels (Weirdly, despite the two loose NDS spokes the wheel was still true, probably because the wheel is so heavily dished that the NDS spokes are actually doing very little! I have felt/heard the wheel flex once or twice when under duress).
The world seems to have moved on to 12mm thru-axle front and rear now and I did build some 12mm thru-axle wheels for my commute bike using Shimano 105 hubs, but searching for a 135mm QR disc Shimano hub only comes up with XT mtb options, either the old style M756 with 6 bolt disc mounting ( I have used this for various MTB and commuter wheel builds in the past), or the current M8000 which is centrelock disc mount so matches the Mavic hub I am replacing. Front hub was relatively simple and was dictated by my desire to only have 28 spokes at the front with 32 Rr. This means the hubs are not a perfect match as the 28h hub was dropped from the latest generation.
I ordered my hubs and revelled in the sparkly shinyness when they arrived..... I then ordered my rims. Until my last set of wheels I have always used Mavic rims and never been disappointed..... until I used a set of Open-Pro disc rims that started splitting around the nipple holes within months!!!! I then discovered on the web that I was not alone in this and the rims have a hopelessly low max spoke tension rating and the problem was common. The Open-Pros were replaced with DT rims and problem solved. For some reason I decided to give Mavic a second chance when I found the Gravel/dirt A1022 which sounds perfect for my intended use this time around....
So perfect? Strong, light, easy to get tyres on/off and designed for a bit of rough treatment. I hope my choice of Mavic doesn't come back to bite me!
When the rims arrived something odd caught my attention. The spoke holes were way off centre, in fact the rim profile was skewed to one side. They were assymmetric! I have checked all the retail info and even Mavics own spec pages and NOWHERE is this mentioned, you'd have thought they might tell you such a key fact? Anyway, not a problem, actually a bonus as this would improve the strength of the wheels due to the reduced dishing requirement.
So there is interesting interweb fact #1 for anyone who stumbles across this. Mavic A1022 rims are asymmetric, although it looks like they are no longer made so stock seems to be drying up now? Also, beware because this might bother you, due to the reversed flange offset from front to rear hubs you will need to mount your rims the opposite way round Fr-Rr. If like me you have minor OCD tendencies you could find this upsetting. I can tolerate it only because I know it is technically the stronger solution....
I ordered my spokes and built the wheels. They are probably technically the best wheels I have ever built. First time I have used asymmetric rims so spoke dishing while not equal is pretty good. I got my spoke lengths spot on so thread finishes flush with the top of the spoke nipple and for the first time ever I paid attention to which spokes were leading and which trailing so the wheels are hopefully best suited to handle drive force at the back and braking force at the front. Despite not building for weight reduction, using more spokes than the 24Fr/24Rr original wheels and MTB hubs rather than road versions my wheel build has knocked 150g off the wheels.
Now for interesting discovery/fact #2. When I built up the wheels with tyres, discs etc it was only when I came to finally mount the 105 11-32 cassette that I found something else was amiss. The cassette lockring wouldn't engage with the freehub. It was almost midnight at this point so I initially thought I must be mistaken or doing something wrong, but no, no matter how I tried the threads just weren't even close to catching. A short while later, vernier caliper in hand I found the reason. The freehub body was 2mm shorter than the 'normal' one. The 'normal' freehub that has been the shimano spec suitable for 9/10/11spd cassettes for years was apparently different on this current XT hub and this was news to me. Turns out Shimano have reduced the cassette body by 2mm to 35mm for 11spd MTB while sticking with the 37mm freehub for its road groupsets (105/ultegra/etc).
***EDIT: Turns out I got this slightly wrong. Just done some additional reading (as well as measuring the freehub depth on one of my XT M756 hubs) and it looks like freehubs were always 35mm deep but Shimano went to 37mm for 11spd road cassettes while retaining the 35mm set-up for MTB by slimming down the cassette spider as I have done.***
Options at this point were limited and not very appealing;
- Buy an MTB cassette. But this would be 11-40T and require some serious tinkering to get it working on my Ultegra equipped bike, resulting in stupid ratios I didn't need or want.
- Buy a suitable non-Shimano hub and rebuild the wheel. At this stage not really desireable, and besides, I like shimano rear hubs.
- Machine 2mm out of the back of the cassette spider to make it fit. There appeared to be enough room to clear spokes and for the mech to operate through the full gear range but this would render my hub/cassette combination unique meaning I won't be able to buy spare cassettes 'off the shelf' in the future.
Trial mod has been done (thanks to a work colleague who has a DIY CNC machine in his garage!!!) and fits/works perfectly so I just need to get my spare cassette machined to match now and that should be me set for another 4-5yrs at least before I need to get any further cassettes machined.
I apologise for the rather long and possibly boring thread, but this info just doesn't seem to be out there so someone is bound to find it useful, especially if you want to run normal/sensible cassette ratios on an MTB hub
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