Bicycle Mechanics - Rim weight limit?

Well heres my problem, I'm 6'6" tall, and 328 pounds. I just got a trek 400 last week and im a little worried of what might happen to the rims. It has a set of matrix 700x32C. SO what is the average weight limit for these kinda rims?

I don't know what the limit is for those rims. What is more important is the number of spokes and the tension on the spokes. How many spokes do you have on each wheel? Be sure they have plenty of tension. Loose spokes make a weak wheel. The tension needs to be high.

Yea, the Build quality matters, the rim is part of the whole, and then there is maintainence and tire inflation being kept Up.

OEM parts will often be chosen for price, unless the premium stuff is included, then the higher price will reflect that .

jessew, If I'm not mistaken the 400 hasn't been in production for awhile, meaning the wheels may well need a look at anyway. Take it to your local bike shop and have them evaluate the wheelset. Wheelbuilding is part art and part science, and I'm missing one of those two elements, but a good wheelset is money in the bank.

Brad

I agree - those rims and suitable tires will handle a lot of weight load given proper spoke tension. It would be worth your time and money to have a professional wheel builder (independent or an experienced on at your LBS) evaluate the wheels, as there is no way for us to know what state they are in on that old a bike. If the rims are undamaged, including not side-stressed, then a good true/round/tension job should give you a reliable set. I would expect to pay $50 or more.

Yea, the Build quality matters, the rim is part of the whole, and then there is maintenance and tire inflation being kept Up.

Good advice. Fully inflate both tires before each and every ride.

Properly built wheels are amazingly strong. Twice I'd had cars back into me catching my front wheel and rolling their rear bumper onto them high enough to lift one rear wheel off the ground. (thank god they weren't front wheel drive). In both cases I was able to ease them forward and off the wheel with zero damage, and that's on 350gram tubular rims.

Your factory wheels will hold up for a while then go out of true. I'd wait until then to have them re-trued and tensioned optimally, and even be willing to pay a good wheelbuilder extra, rather than the pro-forma tune up.

That said, weight is only one criterion affecting wheel life. As others have said, quality of build is a major factor. So is tire cross-section, so you might consider fatter tires, at least replacement time.

Lastly your riding style is possibly the most important factor. Over 40+ years I've learned that weight is trumped by riding styles and I've known gorillas that rode like ballerinas, and never had issues, and ballerinas, including 1 100# professional dancer that rode like gorillas and could destroy wheels as if they were made of tissue paper.

Try to help yourself, by getting out of the saddle for the worst bumps, developing a smooth pedaling cadence, not overly leaning the bike when horsing up hills in too high a gear, and learning to use your knees and a loose grip to let the bike float under you through rough pavement sections.

If and when these wheels die, consider having a builder of high repute build your replacements using components most suited to your weight and needs.

Before we go further I need to clarify something. You said you "just got a Trek 400" - is that the correct model, because Trek has not built the 400 for many years.

I think it might be an old 400. Since it has Matrix rims, a house brand that Trek dropped some time ago.

It is a 400. I got it used for $30 wensday. I'll probably get it up to the bike shop next week seeing as i need a new front inner-tube now.

Gee, for $30.00 plus the cost of a new tube, you really can't go far wrong. If the rest of the bike is in decent shape, you've saved enough to get quality wheels rebuilt on your hubs when the time comes. Just don't expect to pay less than $15.00 each.

I was airing up the front tire, and for some reason even with the valve adapter, i can't get my gauge to tell me the air pressure. I got it up to around where I thought it should be and ka freakin boom, there goes the inner tube.

I was airing up the front tire, and for some reason even with the valve adapter, i can't get my gauge to tell me the air pressure. I got it up to around where I thought it should be and ka freakin boom, there goes the inner tube.
Ah, you said valve adapter, meaning , I guess, you have presta valves. Were you using a pump, or airing them up at a gas station?
If you have a pump with a dual head and a pressure gauge, use the appropriate fitting for the Presta valve without the adapter. You should get a pressure reading as you pump.
If you are checking the pressure with a regular tire gauge, it won't work because the air pressure in the tire will close the valve as soon as you remove the fitting.

If it's anything like my '87 400 those are 36 hole Matrix Titan on Maillard 500 hubs, decent spokes and eyeletted. I have over 12K miles of potholed urban commuting on my
'88 Trek 1000 with the same wheels and they have been absolutely bulletproof. That said, I'm about half your advertised weight. I have heard rumors of cracking along the spoke eyelets, but have never actually seen it, at least on my 2 sets.

I'm with FB - run'em until they need work, then pay a competent wheel builder to properly tension & true them.

You stole that bike for $30 - I paid $150 for mine last spring and I bought it only for the frame - that should be a nice Reynolds 531 frame.

You should probably regrease the wheel bearings minimum, better yet the bottom bracket & headset too. Unless someone has done it, your running 20+ year old dryed out grease in those areas.

http://www.bikeforums.net/showthread.php?426038-trek-1000-wheel-question&highlight=matrix+crack

Ah, you said valve adapter, meaning , I guess, you have presta valves. Were you using a pump, or airing them up at a gas station?
If you have a pump with a dual head and a pressure gauge, use the appropriate fitting for the Presta valve without the adapter. You should get a pressure reading as you pump.
If you are checking the pressure with a regular tire gauge, it won't work because the air pressure in the tire will close the valve as soon as you remove the fitting.

I was using one of the AC's that plug into the cigarette lighter bay in your car. Do they make gauges specifically for presta valves?

I was using one of the AC's that plug into the cigarette lighter bay in your car. Do they make gauges specifically for presta valves?

Yes, there are gauges that will work, but a bike pump with an integrated gauge is a better way to go. It gauges the pressure as you pump.
Either way, you only get a pressure reading when the valve is held open.

OK, given your weight and what you paid for the bike I would not wait for either a wheel tune-up or an overall look at the bike. Things like poor spoke tension, chain wear and bearing maintenance are best attended to before problems arise - your experience will be much more enjoyable. I don't know if FB's note was a typo, but building rims on your old hubs will cost more than $15 just in labor each. I would say $25 each would be more like it. My figure of $50 for a full true/round/retension on the other hand may have been on the high side.

My only caution would be to make sure the shop spec's exactly what they are going to do. Too many "tune-ups" I have seen are "Put it in the stand, check the brakes and derailleurs, turn a few spokes and squirt some lube and wipe it off." Not my idea of even a minor tune-up. Also instruct them to advise you if they find anything while working on the bike that needs attention and was not in the original estimate or work order.

I got ahold of bike doctor earlier today. For $60 they check the deraulers, hubs, spokes,chain, and brakes. I'm not sure if this is worth it or not, i mean it is double i paid for the bike, but then again it's a nice bike.

You stole that bike for $30 - I paid $150 for mine last spring and I bought it only for the frame - that should be a nice Reynolds 531 frame.

I've got an '88 Trek 400 I found in the trash pile at my apartment complex. Frame was in decent condition, and seriously, how often do you find a 64cm bike in the trash? (First ever dumpster find that actually fit me properly!)

Car tires are 30 psi , Bike tires are 70 psi or so, Buy a hand gage that goes to 100.
Get a Floor pump with a Gage , I have a 30 year old Silca Pista. still works..
Italian~ Pista is Track, Strada is road..

My wife commutes daily on a Trek 420. It's a great little bike. I also paid far more for it than you did, consignment from my preferred LBS. It's in spectacular condition though, clearly lived indoors/garaged for it's life. It also came with Matrix rims, but 32 hole, not 36. Great little bike, and the low mileage Suntour components are holding up quite well too. That reminds me though, I haven't yet done a hub bearing service on it. I'll definitely need to get that done before winter. Here's a picture from a little Christmas day cruise around town on our commute bikes this last year. It was mid 70's. :thumb: Oh, and the SMP saddle is on loan to her from my newer Trek, I'll be stealing it back shortly.

http://i41.photobucket.com/albums/e260/Tunnelrat81/Christmastime004small.jpg

-Jeremy

I got ahold of bike doctor earlier today. For $60 they check the deraulers, hubs, spokes,chain, and brakes. I'm not sure if this is worth it or not, i mean it is double i paid for the bike, but then again it's a nice bike.

Well, you can't go by what you paid but by what the bike is worth, and it should be worth more than $90. There is no way to tell if the work is worth $60 - depends on what their standards are for such work. I have no idea what "check" means, but I'll tell you what. If you lift the front wheel off the ground and it rocks back and forth several times, yet has no side play and runs very straight through the brakes, with even spacing on both sides, the spokes are evenly and firmly tensioned, and the rest of the bike looks clean and everything moves easily, then you at least got a fairly decent job.

The reason the tube blew probably had nothing to do with the compressor. Either the tube was pinched between the rim and the tire bead or you need new rim tape.