ixcuix

I have a bicycle with a Shimano 7 speed internal hub with a coaster brake. The coaster brake does not seem to be grabbing very well. This bicycle does not seem to have been used very much at all. Any suggestions on how to adjust the coaster brake so it grabs better.
Thanks TM

veganbikes

Has anything changed? Have you noticed the brake has gotten significantly worse? Coaster brakes are not good brakes and will never feel that strong. Your front brake will always have the most stopping power but of rear brakes coaster brakes are the weakest. There was a series of races for what we now know as Mountain Biking called Repack because all the grease would melt out on long descents and the hubs would need to be repacked. I am quite sure Repack Rider has plenty of excellent stories of this if you so care to learn some history and you can also pick up his book Fat Tire Flyer (I am not getting paid to say any of this just love history and cycling)

If the frame can accept a front brake add a good front brake of some sort and that will help you out quite a bit or even a rim brake at the rear if you can.

Though if you want to play around with it Sheldon Brown would be a good resource. Though really it is just packing it with grease.

Thinking about it this might be a good waste of that really high end Krytox 240AD grease used in Aerospace/Aviation. It is expensive but is designed to handle high temps a little 8oz tube is only $750 or so.

Geepig

[If the question asker has something, try to work with what they have got. For example I ride coaster brakes every day - but I am smack in the middle of the central European plain and so comments about grease melting out during mountain descents are irrelevant.]

You say that it does not seem to have been used much. Sometimes the oil/grease in the hub hardens over time and prevents fully movement of the components, so their effectiveness reduces or they do not re-engage cleanly after using the brake. It sounds unlikely that it has the kind of mileage on it to wear it out.

How far do you have to back-pedal to achieve engagement? About 1/8th of a turn on the pedals is typical. Any less and it will accidentally engage while you coast, anything more and it takes more time to engage. The first things to check are that the chain is lubricated and well adjusted, and that the hub reaction bar is securely fitted..

Ride standing up somewhere open, like an empty carpark, get up a little speed and reverse pedal hard with the cranks parallel to the ground. With this amount of force the rear wheel should lock up on a dry smooth surface. If it does the brake is OK and just needs getting used to. If it does not, do it again a dozen times and see if it starts to improve.

When I buy a coaster braked bike these are the first things I do. The most common faults I see are hardened oil/grease in the hub (which means stripping it, so the last option), incorrect chain tension, poor chain lubrication, collapsing bearings on the sprocket side, split hub due to bearing failure and chipped internal parts. Check that the rear wheel feels secure and that there are no odd bearing sounds.



2 local bikes, 50 year old designs, 2 coaster brake hubs (velosteel) and 1 handbrake. Oh, and long-lasting plastic pedals

veganbikes

I mentioned a lot in my post, shame you missed it. I get there are large swaths of people who love poor technology that is fine, heck I was dragged kicking and screaming into the SmartPhone era. However I am not going to say coaster brakes are great, people use them and in flatter eras compared to themselves perform much better but as a whole not a great system. Do you deny that a front brake is better and provides more stopping power?

The main thing though is the first two questions in my post. Has anything changed? If nothing has changed and it feels the same as the day you got it, that is a good sign it is the braking system being the braking system if it has changed then maintenance would be in order but even that won't really make it that exciting.

kingston 

https://si.shimano.com/pdfs/sm/SM-IHG-INTER7_ENG.pdf

Geepig

Well, to really appreciate coaster brakes it helps to stop thinking about power. The power of my discs on my mountain bike is very high, and those on my car even higher, but then on a small wheeled folder it can be easy to smack a disc into something while carrying it folded or coming off a curb wrong - significant if you are a commuter. All the power in the world vanishes if you damage the disc - and thus the definition of 'great' for my daily commuter folder is not the same as for my mountain bike. Poor technology? coaster brakes are in regular use in Europe from the Netherlands to Russia and, probably, beyond. The lack of hand brake simplifies maintenance, and the coaster brake is also rugged, so in terms of technology we have to consider appropriateness. Would a track bike be good on a BMX track, whatever its level of technology? The coaster brake is not poor technology, just appropriate technology, offering the required level of braking power, avoiding impacts and jamming with twigs or snow, staying warm in sub zero conditions by riding it slightly and hitting the right price point for people who have other things to spend their money on: a great choice. I have five bikes with coaster brakes, and having no reason to let go of the handlebars on difficult downhill descents while off-roading, allowing the rear end to slide out one way or the other in a controlled manner, is an experience in effectiveness.

So if something's not your cup of tea, it's just not your cup of tea, not it's fault.

ixcuix

ixcuix

Big thanks for all of the feedback in regard to my 7 speed coaster hub. I am going to try some of the suggestions. Thanks very much for the post of the Shimano manual.

Thomas

2old

I disassembled a SS coaster hub, cleaned & greased, and function was restored, but possibly orders of magnitude more difficult with a geared one. Also, as Geepig above, coaster brakes have always been excellent for me.

veganbikes

Well to think about braking it is important to think about power. But when people invest in something heavily of course they will promote them heavily. I agree yes no hand brakes = less cables and housing and all of that but again the issue with the OP was the brake not grabbing well which likely translates to less power. However yes I get it you love coaster brakes that is great I am glad you are cool with it.