Build Tips For a 29er Trail Bike Part Two

Posted by FatBob on June 15, 2010

This a Continuation of the trail bike build suggestions in answer to Steve. Steve submitted a build request to "Bob Builds Bikes'. I thought it would be helpful to post my answer to the world as I am sure many people wonder about this kind of thing.

What should we talk about next? I think the next subject should be wheels and brakes.

First lets discuss brakes. 29eronline specs Shimano SLX brakes on the test rigs. I have been a long time supporter of Shimano Brakes. My affection started out with Shimano four piston XT brakes that came out in about the year 2000. they have since improved the design of course.

Why I like Shimano? They are easy to bleed. They use mineral oil, which is pretty harmless stuff if it gets on you or on your bike. This is as opposed to DOT fluid which can burn your skin, ruin the finish on your bike and is environmentally not good. Shimano brakes offer plenty of power and excellent modulation. they are easy to align when you install them. Last but not least they are pretty affordable and easy to get parts for. I would say if you are traveling, almost any bike shop will have brake pads and be able to service these brakes.

The cons? They are heavy. That is the only con I can think of.

I have a set of Formula R1 brakes and have ridden Magura Marta SL brakes for a couple of years. Both of these brakes perform well. They are both light. They are both very expensive. They are both more expensive to maintain. The Formula R1 brakes will be harder to find parts for. I recently snapped a bolt in the Formula R1 brake levers. I had to send the whole brake back to Formula to get a new master cylinder. Formula had excellent customer service and fortunately had what I needed to fix my brakes. The retail of this would be well over $130. For that much money I could buy a complete Shimano brake set! Needless to say I went to the hardware store and bought 4 steel bolts and replaced the pretty anodized red ones that were sent with the brakes. The Marta Brakes are excellent feeling and I really like them. I did snap one of the carbon levers. If this ever happens to you read the directions on how to change the levers. I did not. Evidently doing it wrong can screw up the brake. Again the cost of the brake lever assembly cost about what an SLX brake set(front or rear) can be bought for online. Plus this was a special order item. It took a week to fix.

Long story short. The high end brakes work well but are harder to service unless you go to a well equipped shop that keeps the small parts in stock. It is also debatable that they work better then Shimano brakes that cost half the amount. If you don't mind a little bit of pork the Shimano's are hard to beat. I don't have much to say about Avid except I have little experience with them. I have had a couple of warranty items from them recently and I finally gave up trying to get the warranty's taken care of. I am not sure if Shimano is any better which is another topic all together.

As far as rotors go. We use 180mm Front and 160mm in the rear. If I had to do it over I would do 180mm front and rear. This seems to be plenty of rotor for XC and trail use in most locations I have been in. I went through a 200mm rotor phase but feel it is really overkill for most riders needs. Take it for what it is, just an opinion.

Wheels: This topic is huge! I can not possibly cover it all. I guess we can talk about custom hand built and pre-built. A pre built wheel to me is a wheel set that has been factory built as a dedicated wheelset. Typically they require special proprietary parts. The problem with these types of wheels is that typically it is harder to get them serviced. The parts usually have to be ordered directly through the company. The spoke gauge and strength is picked for a "standard" weight range and and a dedicated purpose. This is where type casting riders comes in. Do you ride all mountain? Cross country? Enduro? Freeride? Light freeride"? Aggressive all mountain? Light all mountain? Aggressive trail? Down Hill? Who Knows! I guess all of us ride trail. So trail bike it is.

Typically I use the marketing type casting to pair a wheel set to a rider weight and riding style. If you have a 250 LBS rider that likes to jump every indentation in the trail or lives for rock gardens stay away from wheels that advertise light. This is where "all mountain" wheels come into play. If the 250 LBS rider loves rock gardens and brags about all the parts he breaks then this is where a custom wheel set comes onto play.

Alternatively if I hear of a light rider that wants a wheelset that can handle "trail riding" and admits to being a little timid I want him on a fairly light wheelset. Donn O is about 150LBS. He runs Stans 355 rims, light spokes, alloy nipples and DT-240s hubs,rides aggressively and does not have wheel problems.

I am 215 LBS and rode a similar wheel set and hated the flex.

Basically a custom wheel set can and should be specifically designed and built by some one familiar with the terrain that you ride and is willing to listen to your needs and wants and come up with the best compromise. There is no easy way to do this and no generic answer.

The dedicated wheel sets have their place. They are typically loaded with technology. Also bang for the buck you usually get that technology for a very competitive price. As far as budget wheels bang for the buck there are some killer looking wheels on the market. I have no recommendations as I have not ridden any for any length of time.

Yes I know this wheel information is vague. I would love to test dedicated wheelsets and give our feed back when we get them we will post and tell you who would get the most out of any given wheelset.

What about Carbon rims? Again we have not ridden any so have nothing to add. Does if freak me out? YES! would I try them. YES! They offer a lot of promise but to me need to be proven by someone who is not sponsored by the company. I will not throw my money at them. Before I get some comment by a carbon zealot I know that Steve Peat races them Down Hill on the world cup circuit. I dont care. He gets free wheels any time he wants. It only has to make it down the hill one time. In defense of carbon wheels, under Steve Peat aluminium wheels wont hold up either. I would test them if a company sent them to me. Does any body want to know about carbon rims? If so I will see if I can get set.

Another big Con of carbon wheels is that if they do break it will cost a small fortune to replace. If I destroy a Stan's rim it will cost $85 to scrap it and $35 or so to get it rebuilt plus max $60 for spokes. Those would be some expensive spokes. So total $180. Do that to a carbon rim! You still need to buy spokes and pay labor plus $850 for a Edge Composite rim! The edge rims are 450 grams and Stan's Flow rims weigh 470 grams(claimed) If the Edge rims puke do you want to pay $850 to replace one of them? Will they fail? Who knows? We will see in a few years and at those prices I will want to have them on my bike for a few years.

So there are pro's and cons to factory built and hand built. at this point as long as you maintain either set, check your air pressure in your tires, use adequate air pressure in your tires(protects your rims) you should be able to get good service out of either type.

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Build Tips For a 29er Trail Bike Part Two

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29er Build Questions Answered: Stem, Bars, Seat posts, and Grips for a trail 29er

Posted by FatBob on June 4, 2010

29er Build Questions Answered: Stem, Bars, Seat posts, and Grips for a trail 29er

Steve from Winston Salem wrote a build request under the "Bob Builds Bikes" tab on 29eronline. Here is his question. We have hidden the personal details for his privacy.

Steve bought a Turner Sultan Frame, and a Fox fork with a 15mm QR axle. He rides road bikes but wants to ride mountain bikes. He is interested in aggressive trail riding. The area where he lives has a good technical trail and the North Carolina mountains are close by. He comes from an athletic back ground and also rides motorcycles. At 52 years old he doesn't feel that he will be jumping anything too large. At 6' 4" and 220 pounds and how and where he rides we will have to pay attention to the parts we pick. Lets start with the easy stuff. The stem, handle bar, seat post and grips.

Stem: At Steve's height I would recommend a 90-100 mm stem. If Steve purchased the correct size frame, on a 29er this should work well for him. The Shorter stems make for more precise handling and smooths out the front end as far as side to side movement. A long stem has kind of a break away point. This is hard to explain but I refer to it as wheel flop. When you turn a really long stem to the right or left it flops instead of smoothly transitioning. This is exaggerated with 29er wheels.

In addition to the "Flop factor" The shorter stems bias your weight toward the back of the bike. This is a much more confident descending position.

Three things happen here that are debatable negatives.

First is fit. Older 29er geometry was still leaning to the short side as far as top tube length. For instance we felt that the Ventana El Rey was not suited to a short stem. Also Lenz bikes are still short compared to the seat tube height. For some this works really well so there is obviously exceptions to the short stem rule.

For instance the Turner Sultan in the size Large frame has a 24.25 inch effective top tube. The Large measures a 19" frame at the seat tube center to top measure. The Ventana El Rey size Large measures to a 19.5 seat tube.It has a 24.00 top tube. Obviously the same rider is going to need to run a slightly longer stem on the Ventana to get a similar fit. Of course this is not as simple as it sounds as other factors come into play. Like seat post set back, Seat tube angle(higher the post and slacker the angle, the longer the theoretical top tube is). In our case the Sultans geometry really rides well with a shorter stem. In my opinion even the 100mm is not my favorite. I personally ride a 80mm on most bikes even if that means I am a little cramped. The handling is so much better I would rather make the sacrifice in a little comfort, which is also a general and subjective statement, for the quick, precise handling the shorter stem gives.

Second potential negative, Weighting the front wheel: On steep climbs with a tall front end and your weight shifted back, the front end of the bike can become light. Worst case the front end gets so light the front wheel lifts off the ground and you loose control and fall. In the last 5 years that I have been riding and introducing others to 29ers I have only seen this happen to one person and it was his first time ever riding a mountain bike. In addition to that he was using flat pedals. It happened to him on the down stroke.

Modern 29er geometry and a little technique eliminates the problem. I can ride the steepest section of local trail and never have a problem with this. 29er wheels are much more sure footed then a 26er. Learn to slide your weight forward in your saddle. Use the nose of the saddle, lower your chest to your bars and pedal away.

Third is leverage.: Just like any lever the longer the lever, in this case your stem, the easier it is to lift an object. In this case your front end. You see this in trials riding. I am still bias to a shorter stem even for this. It comes down to technique. Does the ability to shift your weight back easier with a short stem make up for less leverage? In my opinion I would say yes.

Next topic is handle bars. For aggressive trail riding and 29ers think wide. Think about 27(still not my preference) to about 30 inches. I ride about 27.5" bars. I have been riding wide bars(and short stems) for about 15 years now. Wide bars smooth out a 29ers steering. They increase leverage and add stability.

Down sides to wide bars: Fitting between trees. There are a couple of places were I have to lean my bike over stick my bars behind a sapling and lean the bike the opposite way to clear a skinny gap between trees. If you live in an area where clearance becomes a problem you can always cut your bars. I would say that trails this skinny are not very common especially with the new methods of trail building.

Seat post: Should you buy a set back or a straight? This is really based on fit. There are not a whole lot of people that anatomically need a set back seat post. I have lately started to prefer the set back posts. It seems that when I line my self up in the traditional fit method, that I develop pains in my hips. It is really too hard to tell you if you should be on a set back or straight post. If I had to pick I would say start with a straight post. By the law of averages most people will fit this just fine.

The real advice is 1) get professionally fit. 2) listen to your body!

The brand I think is the best is Thomson. They are pretty bomber and spare small parts are readily available. I am running the Easton EA-70 and it seems the bolt on the front of the post is a little awkward and seems a little soft as I have somehow bent both the front and rear bolts.

Also the finish does not seem to hold up. I am really wanting to try the new 2011 Haven parts that were previewed at Sea Otter.I will report on them when they become available. For now the Thomson is the gold standard.

If you need a less expensive seat post the Sette apx at Price Point actually is very nice for the money. The Truvative seat posts are decent as well.

To add to seat posts you can run a dropping seat post. As far as fit you can get set backs or straight dropping style seat posts. The brand I ride is a Crank Brothers Joplin R. I would try others but for now I own this one and am not inclined to spend another $300 on a different one

especially since it is not a 29er specific part. It only comes in a 30.9 or 31.8 so if your seat tube diameter is smaller you will need to look at the Gravity dropper brand.

For aggressive trail riding I think they are great. Not completely necessary as I have ridden the same terrain with out one. However it is really nice to have the option to lower your seat post on the fly without getting off the bike. The lower saddle allows you to lower your center of gravity for cornering. It allows you to get lower and back further on really steep terrain. If you like to bunny hop or scale tall logs, the ability to keep the seat out of the way makes these moves easier. I switch back and forth between a dropping seat post and a standard one.

Grips: Really there is only one option that I feel I can recommend with no hesitation for trail riding. Lock on Grips. ODI, Lizard Skins, Specialized, and others make a large variety to choose from. Our test bikes all run Oury Lock on grips. when they get wet they don't slip. No hair spray or wiring required to keep them from slipping. i would get a spare set of clamp bolts as they strip out fairly easy.

Other then that I could suggest looking at ESI silicone grips. The only real advantage of these is weight. They are super light. They also don't slip when wet but don't last near as long. Also when you are swapping shifters, brakes, dropping post remotes, or handlebars they are harder to remove.

Next post we will continue through the rest of our parts.

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29er Build Questions Answered: Stem, Bars, Seat posts, and Grips for a trail 29er

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Stan’s No Tubes Tubeless Review By D.O

Posted by FatBob on March 13, 2010

Stan’s No Tubes Tubeless Review By D.O

I’ve been using tubeless tires since 2003 and I am convinced that for me tubeless is a substantially more reliable system than tube tires which suffer from constant thorn prick flats and pinch flats. In seven years of using tubeless tires I have had to walk out of the woods 3 times and rode out on tires with low air pressure maybe another 3 times. Of the three walkouts two were do to sidewall tears – one by a sharp pointed stick and one by a sharp pointed rock. The third flat was due to burping the tire and loosing the sidewall seal. Burping occurs more often with big aggressive rider that jump a lot and land crooked putting high side loads on the bead. Maybe I am just lucky but compared to the number of flats I used to get with tube tires that’s a pretty impressive track record.

I have been using Stan’s Sealant the entire time. The beauty of going tubeless in combination with Stan’s is even if you do get a small puncture it leaks so slow you have plenty of time to complete your ride unlike the almost instant deflation of a tube tire. The other advantage of going tubeless is the ability to run lower air pressure without worrying about pinch flats – I typically run only 28 PSI in my tires.

After using Stan’s for seven years I have come to suspect that Stan’s is not real good for your tires except for keeping the air in. In fact I think that Stan’s will eventually attack the rubber compounds used in the tires. Over the years I have had few tires which developed soft spots / bubbles or bulges in the tires on brands including Kenda / Continental / Maxxis.

A visit to the Kenda web site reinforces this belief by flatly stating that they do not recommend liquid sealant, and its use in there tires will void the warranty.

Stan's goo drying in a set of converted tires

Getting past the bad effects of sealant on your tire it does have huge advantages.

You can gain the ability to use normal tube type tires way beyond its original design specification that’s right I am actually running regular tube type tires tubeless. Stan’s Sealant acts like an ultra thin liquid tube to hold the air in tube type tires.

Fresh Stan's in a tire ready for conversion to tubeless

Losing the heavy inner tube makes for an incredibly ultra light wheel setup which is even slicker for the bigger 29er wheels. You can cut a huge amount of rotational weight with this little speed secret.

Typically tubeless tires are built with substantially heaver construction to compensate for not having a tube so there is a weight difference between the two types.

I’m sure the tire company’s product liability lawyers cringe when they hear about riders doing this and at first I thought you would have to be half crazy to try it, but then I found out you can build niner wheel lighter than a conventional sixer wheel with this slick little trick.

Of course this is risky and we would never recommend that you ignore factory recommendations but Stan’s promotes this right on there label

How risky, I found out the hard way; I recently had a big crash because my back tire leaked down during a ride, and this unnoticed loss of air affected my bike handling during some especially aggressive riding which gave me a chance to stop and bond with mother earth.

I later discovered that the sealant had dried up allowing the thin sidewall to become porous and slowly weep air. The label warns that this can happen especially during hot weather I had to redose my tire with a new shot of sealant to bring back the air holding properties of those extra thin side walls. Besides drying up I have experienced another phenomenon wile using Stan’s – a Stan’s man will form inside your tire (see photo) this little guy can roll around and potentially wear on you tire from the inside. This big glob of Stan’s has got to affect the dynamic balance of the tire but I’m not sure bike riders go fast enough to notice this. Stan’s claims that there sealant will seal holes as big as 1/4” now that big glob I found might seal a golf ball size hole but even sealing ¼” hole as they claim might be a bit overstated, I think if you had a hole that big in a bike tire there would be major structural damage to the tires fabric casing and you would be taking an unacceptable risk by doing any more than limping out of the woods with it.

a Stan's man. Some people call them Stan's boogers either way they are kind of gross looking.

The other phenomenon I’ve noticed with this sealant is as your tire gets older it will start to bleed. This is probably the result of small tire penetrations caused from old thorn prick holes / broken off thorns imbedded into the tread / tire damage from hard impacts and probably by the sealant attacking the rubber. When this becomes wide spread on your tire it’s a good indication that it is almost time to replace your tire.

Pro - increased reliability / ultra light 29er set ups possible / allows the use of slightly cheaper tube tires

Con – decreased tire longevity / sealant can dry up or form little Stan men inside your tire / voids some tire manufactures warrantee

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Ergon Grips

Posted by FatBob on August 22, 2009

Ergon Grips

This is a review from Donn. It is obviously not 29er specific but maybe it will be helpful. Ergon Grip review: By Donn O Very few new mountain bike components catch my attention, but I recently stumbled across one that made a huge difference in my riding comfort. While building up my new Niner RIP 9, I had to pick out some grips for my new bike. While scanning Storm Endurance's parts distributor catalog I had planed to choose some grips with a cool design such as hot chili peppers and figure out what color would contrast nicely with my new bikes paint scheme. That plan went out the window when I noticed the Ergon grip selections in the catalog, sure they were way more expensive and a little heavier than normal grips but building the ultimate bike called for something special; boy I am so glad I took the gamble. I picked out the Ergo pro race GP1 Leichtbau model - mainly to go light as possible. Your body directly interfaces with your bike in three places - your pedals / seat & handlebars. Of these three interfaces – foot / butt / hand - the hand is your most intricate body part.

Most of the sports I like place huge stresses on my hands – windsurfing / wakeboarding / biking / motorcycling / kayaking which all require lots of gripping. So anything thing I can do to take stress off my hands is worth looking in to – look at all the people that have bad hands just from typing too much on computers. With regular style grips, you have two choices – thin or thick, then you couple that with various types of gloves with different levels of padding, and maybe you add bar ends. Ergon has taken this most important bio-interface to an entirely new level! During my first test ride on my new bike, I was so amazed by the ergonomics of the Ergon grips that it was hard to pay attention to the rest of my new bike. The Ergon folks really have figured out what it takes to couple your hand to the handle bar in the most comfortable manor possible. These shaped grips clamp on to the handle bar for super easy installation and angle adjustment The innovated shape provides a large contact area for your hand spreading out the load to away from your fingers and more onto your palm. Only your thumb and index finger encircle the grip. The rest of your fingers just tuck under the grip in a comfortable C shape with most of your weight resting on your palm. Unlike regular grips with their straight shape, Ergon grips have a P like shape which captures your hand, there is no tendency for your hand to slide off the end, in fact it’s like you have an integral bar end. The grips are checkered like a gunstock, this allows for added holding power, though on long rides of more than 20 miles or more they start to rub you hand some. Check out their informative web site at ergon-bike.com and browse all the different grip models they manufacture. I would give this product my highest rating!