For an older road bike, with 27" wheels (not that size matters vs. 700c). I'm building up an older Schwinn Le Tour Luxe for a friend, to be a relatively nice road bike for "real" riding and for commuting. Nothing off-road, but not always perfect pavement (no curb-hopping, though). Now, at 185# myself, I usually end up with slightly bent axles on the freewheel side of the rear hub. A solid track axle (good-quality) will help to avert this, of course. But I'm wondering about how this shapes up for a rider weighing 160-165#. Based on people's knowledge and experience, is there much danger of a good-quality Q/R axle bending for a rider of this weight, doing road riding?
Q/R or solid axle on 7-speed freewheel road bike for 160# rider?
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Absolutely not. There are 200+lb pro riders who finish the Tour on hollow axles. But there is a difference between a cheap generic axle and a "good-quality" axle.
When you use "finish" (present tense) it implies taht you're talking about current riders, who use freehub+cassette, not freewheels. Problem with freewheel is that there's a lot of exposed axle between the bearings and the frame dropout, so it's much more likely to bend. There were freewheel hubs (e.g., Phil) designed with extra-large axles, but most freewheel rear hubs have standard-diameter axles. And my question pertains to these.
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It's not the design that is at fault, rather the quality of materials.timcupery said:
Riders have habitually been winning on QR non-cassette hubs for years.
Barry Hoban, Francesco Moser, Mario Cipollini etc all won on standard hubs no problem.
Right, right, right. But none of this answers my question. With a "typical" design freewheel hub, quality axle but not oversized axle, would a Q/R axle be strong enough for a 165# rider for everyday use? In this sense it is the design - there are multiple designs of freewheel hubs, some of which have oversized or reinforced axles on the part that sticks out, others that don't.
Note that axles bending happens over time, while racers may have well gotten new axles every couple of weeks.
Note that axles bending happens over time, while racers may have well gotten new axles every couple of weeks.
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Since 86 I've had 4 freewheel hubs. 3 of the 4 rear axles bent. 2 were Mavic 501's, 1 was Miche. The one that didn't bend was American Classic - it has a non traditional axle. On both sides there is an aluminun spacer which fits over the main axle (which has a bigger diameter). Over the years I averaged about 160 lbs. The Mavic's were the only Mavic made back then, the Miche was lower end and the A-C was the only one made back in 87. One of the big advantages of going to a freehub is that it basically solved the bent axle problem.
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Bent axles are more often than not caused by mis aligned dropouts.timcupery said:
I rode Nuovo Record hubs every day from 83 to 88 without a hitch. They were on a secondhand Alan that was 4 years old when I got it and was stolen in 88. They were ridden in all conditions and I never had a problem. My weight was 160 ish.
Yeah, the American Classic (and the Phil Wood) are two of the good non-trad models I'm thinking of. Campy may have been good, too. But I've had Shimano 105, and others (e.g., "Schwinn approved"), bend on me. Freehub is certainly a better design.
My guess is I'll put a solid track axle on the bike, and that will work well enough for a guy who's not too heavy.
My guess is I'll put a solid track axle on the bike, and that will work well enough for a guy who's not too heavy.
5. . .6 . . .7
I know you're dealing with a 7-speed here, so this is just a historical footnote. Rear axles started bending because cogs were added to the freewheel without increasing the axle diameter. The distance from the bearing to the dropout became longer and longer, resulting in an ever larger bending moment. Very few people bent 5-speed hub axles.
I know you're dealing with a 7-speed here, so this is just a historical footnote. Rear axles started bending because cogs were added to the freewheel without increasing the axle diameter. The distance from the bearing to the dropout became longer and longer, resulting in an ever larger bending moment. Very few people bent 5-speed hub axles.
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I rode Campy freewheel hubs for many years without a problem. I weigh close to 200#. When I 1st started riding I had a couple of Schwinns. Bent / broke real axels were common. When I bought my 1st "good" bike with campy hubs, all the probs ended.
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I suppose those same campy hubs are still butter smooth with no axle play.....
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Does the bike have horizontal or vertical dropouts? If they're horizontal, I'd go with a solid axle or at least bolt-on skewers to avoid movement.
Either way, I'm running a hollow axle in a freewheel hub on my SS road bike right now, and haven't had a single problem.
Either way, I'm running a hollow axle in a freewheel hub on my SS road bike right now, and haven't had a single problem.
Yeah, the QR axles on 7 spd. freewheel type hubs are more prone to bending than 5 or 6 speed versions. That is one reason the manufacturers went to cassette hubs for 8+ speed systems. Having said that, I rode an early '90s Trek with a Suntour 7-speed system for several years without a bent axle (mid-level Sanshin hubs). I have heard that some replacement axles are better (harder) than others, with several people mentioning the ones from Wheels Mfg. as a good product.
Axle bending loads
The largest bending stress at the axle is actually due to chain tension. Consider - when you are sitting on the saddle, there is between 1/2 to 2/3 of the rider weight on the rear axle. But when the rider is standing with all their weight on the forward pedal with the cranks horizontal and the chain is on the inner chainring, the chain pulls forward on the axle with about twice the rider's weight. If the bike hits a bump while the rider is standing on the forward pedal, the chain tension increases further still.
This is why a rear quick release with horizontal drop-outs must be secured very tightly - there is potentially a huge force trying to pull the axle forward.
This commonly believed, but not often the case. The stays are relatively flexible to localized bending at the drop-outs, so don't create much bending stress at the axle.ultimobici said:
The largest bending stress at the axle is actually due to chain tension. Consider - when you are sitting on the saddle, there is between 1/2 to 2/3 of the rider weight on the rear axle. But when the rider is standing with all their weight on the forward pedal with the cranks horizontal and the chain is on the inner chainring, the chain pulls forward on the axle with about twice the rider's weight. If the bike hits a bump while the rider is standing on the forward pedal, the chain tension increases further still.
This is why a rear quick release with horizontal drop-outs must be secured very tightly - there is potentially a huge force trying to pull the axle forward.
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