In getting my bike serviced and ready for the AUDAX - Big Black Crow ride this weekend... by who has to be one of the best bike mechanics in the business - and he lives in Wagga Wagga (Place of Many Crows) - an unusal observation was made ... well unusal to me.
The back wheel rim had developed a concave surface! With calipers the measurement of the back wheel to the front was substantially less- i.e, about 5%.
The view was that possibly - as I tend to brake using more back than front brackes - I had worn the rim enough to then - under 100+ psi cause the concave metal stress fracture on the aluminium rim. I weight about 60- 63kgs.
The immediate solution - premised on safety - was to change the wheel - which we did!
My question though is have others experienced a concave reformation on their back wheel rims - and if so - what is believed to be the cause?
My question though is have others experienced a concave reformation on their back wheel rims - and if so - what is believed to be the cause?
Yes, I changed a rear MTB rim recently for the same reason, plus a few tiny hairline cracks around the spoke nipples. The hub and spokes were still fine, so I built in a new rim, rather than getting a whole new wheel. Hence it cost me $100 instead of a whole lot more. You might be able to build yourself a spare rear wheel.
In getting my bike serviced and ready for the AUDAX - Big Black Crow ride this weekend... by who has to be one of the best bike mechanics in the business - and he lives in Wagga Wagga (Place of Many Crows) - an unusal observation was made ... well unusal to me.
The back wheel rim had developed a concave surface! With calipers the measurement of the back wheel to the front was substantially less- i.e, about 5%.
The view was that possibly - as I tend to brake using more back than front brackes - I had worn the rim enough to then - under 100+ psi cause the concave metal stress fracture on the aluminium rim. I weight about 60- 63kgs.
The immediate solution - premised on safety - was to change the wheel - which we did!
Or at least, the rim.
Quoted message said:
My question though is have others experienced a concave reformation on their back wheel rims - and if so - what is believed to be the cause?
I had the interesting sensation of having a loud squeal from the front disc brake the other day, cruising down second slight downhill from home after a nice little pootle. Sure enough, the pads had worn down to the point that the return spring was contacting the rotor. Nice little warning system that, though I knew they were getting low anyway.
I wonder what I can get for a razor sharp return spring on ebay? Probably a trip to camp x-ray for supplying terrorist equipment!
-- Dave Hughes | [email hidden] "My ambition, naturally, is to have a student quote my own words back to me without attribution in a final paper. That's an office hour I'd look forward to." -- Kieran Healy, on plagiarism
The immediate solution - premised on safety - was to change the wheel - which we did!
Better solution is to just change the rim and get a new one built onto the hub. It'd be stronger than a ready-built machine laced wheel.
Quoted message said:
My question though is have others experienced a concave reformation on their back wheel rims - and if so - what is believed to be the cause?
Simply wear from braking. My rear rim gave out last Easter after 8 years of riding. I'd guess that, even though most people put more brake load onto the front rim, the rear rim and pads pick up more raised dust and dirt, causing greater wear.
